The number of takes I had to throw away because I had ink on my face! You can also discuss this video on REDDIT: stvmld.com/eb_-3xng The sponsor is Brilliant: The first 200 people to sign up at brilliant.org/stevemould will get 20% off an annual subscription.
Walter Lewin sir's channel is going to be deleted because of some Glitch( not exactly).plss help him if you can.He is old He has 1 million subscribers.His channel is his life .He might loose all of his work
Hey Steve, I'm a Nanotechnology Engineer that has a little bit or perspective to share as this kinda sits right on the border between the chemistry and physics that I work with every day. First and foremost, the propulsion you are seeing is definitely as a result of that difference in surface tension you mentioned. In fact this particular propulsion method is used a lot in various fields and usually the forces involved are referred to as Marangoni forces (because they arise from the Marangoni effect). Second, the way the ink spreads out actually screams that there is some surfactant and some phenoxy ethanol, and this is actually counter to one of the points you mentioned. You suggested that if a surfactant was present, the ink layer would break up into smaller pieces which can actually be seen on the outer edges of the trails in your videos. There often appears to be fractures with no external causal force. The other thing is that the pieces then appear to "bounce" away from one another despite neither piece involved in a collision being moving all that quickly. Altogether though there is some interesting Materials Science and fluid mechanics going on here and I'm excited about any follow up videos you make on the subject Cheers
@@moikkis65 A lot of the applications are actually eerily similar to what is shown in the video. Mainly the creation of microswimmers, small pieces of material that move along the surface of water or another liquid. See papers 1 and 2 for more, but one of the other cool things about this is that the surface tension of water changes with temperature so you can actually use heat to trigger this effect. These are called thermal Marangoni effects, while the others are called solutal ones, because they are caused by a solute, something dissolved in the water or other liquid. Thermal Marangoni effect are quite common in situations where there is some kind of local heating such as welding (See paper 3) and crystal growth (see paper 4). The biggest one by far though is using this to clean silicon that is used in electronics manufacturing. Currently manufacturers are working on the scale of approximately 24 nm which is about 1/3000 th the width of a human hair. As a result if even so much as one dust particle or salt spot is on the surface this can lead to a device being defective. To clean the materials used, alcohol is sprayed at a wet surface, which causes one side of the droplets of water to have a lower surface tension and so they are propelled off of the surface similar to how the leaf is propelled on the surface of the water. (See paper 5.) In summary though, many applications are still only in the lab. That said, many of these may start popping up in unexpected places as technology gets more advanced and our control of chemistry goes down to smaller and smaller scales. See these papers: www.nature.com/articles/s41467-021-24996-8 www.nature.com/articles/s41467-019-11141-9 www.sciencedirect.com/science/article/pii/S0921509308001603 doi.org/10.1002/(SICI)1521-4079(199904)34:4%3C457::AID-CRAT457%3E3.0.CO;2-6 pubs.acs.org/doi/pdf/10.1021/la00101a014?casa_token=KCFCgXMmPm4AAAAA:Pr4Io9ornnnSk9VY4izWmcEhZivOdojBMcas0O9IqD1rpfUXivhfeJbwuVLivLnJv4bKYciBW78YHf4
The fractal nature of the ink was the most shocking part to me. I couldn't help but imagine a blossoming flower every single time that leaf boat started up. Really interesting stuff Steve.
it forming fractals means that it had negative surface tension im pretty sure. positive surface tension minimizes surface area by forming round droplets, so the only way it could be maximizing its surface area is if the opposite were true
As an ink developer (but not the kind of a writing pen), I'd say this is perfectly normal and we see it everyday in lab. First of all, solvents used in inks generally have low surface tension to facilitate the wetting of ink on substrates and might help the transfer of ink from the tip of pen onto paper though I'm not sure in that. The low surface tension first causes the spreading of the ink on water, which is a high surface tension substrate. Most solvents are also immiscible with water and have lower density, which makes them stay separated from water and float on top. On the second fact, the pigments usually require anchoring agents/dispersant/surfactants or whatever you call it, to help them disperse in solvents with high stability and long lasting manner. Pigments and dyes used in inks may also poorly disperse in water which prevents them from "dissolving into the water" as in the video. The last fact is that we use various kinds of polymers to give functions to the inks, such as the shininess, water resistance or other desirable mechanical properties. These polymers generally don't dissolve well in water and forms a rigid solid film when the solvent carrier dries away. In sum, the solvent properties (low surface tension, viscosity, immiscibility with water) causes the spreading of the ink on top, and the pigment or dye used in the ink are chemically modified to improve dispersibility in the solvent and prevents them from coagulating/sinking/dissolving into water. Lastly as the solvents evaporates, the polymers in the ink solidifies and what's left behind is a film of water-insoluble polymer, holding pigment or dye molecules that were dispersed in the solvent.
@@natebell4764 Hi Nate, I think you can probably order the resins or colorants online, but I am not sure of your local regulations whether those would be counted as danger or restricted chemicals so beware. Solvent Red, solvent blue, solvent black might be what you are looking for. Resins, there are so many types available and I don't know which type would suit your purpose. You can contact the suppliers and see what types they could offer. In general, acrylic resins/cellulose acetates or vinyl copolymers would be something that we use most of the times that are water insoluble and fast film forming. The last problem is the solvent, which are usually dangerous goods as they are mostly flammable, and you might not be able to get them in large volume. However, you may first try something like paint thinner, which is essentially mixture of organic solvents that is usually compatible with many resins and are immiscible with water.
@DeadlyPlatypus Yes, that's also true. Resins and colorants in inks, whether organic or inorganic, are usually "deposited" onto the substrate and form films when solvents dry away. Imagine you dissolve high concentration of sugar into water, brush the solution on some surface and wait for it to dry, which then you will get a dried film that is not thermally set but rather a physically deposited and slightly chemically set layer of sugar molecules.
What I like about this channel better than other science channels is that he asks us questions and shares his investigation process, instead of just giving us facts and answers.
I sincerely love hearing, "I don't really know why it does that," in this video. It sort of emphasizes that you can pursue a general understanding of a scientific phenomenon to a satisfactory degree without necessarily ruining the mystery of it.
I latched onto that sentence as well. It made me realize, along with his chain fountain series, that Steve is one of the few TH-camrs I watch that conducts original experiments and shares his findings rather than just summarizing what he reads online. Don't get me wrong, I like the channels that summarize difficult concepts to make them easier for the masses to understand as well, but it's amazing to see the lengths Steve will go just to learn about the world around him, whether or not someone else has already done the research before him. I also like that he doesn't need an EXACT answer before posting a video. He is willing to get partial information out there just to spur interest and conversation. It makes me feel like I am actually witnessing discoveries happening today rather than learning about something historical.
Steve Mold is an honest man which makes him great. I am sure though he lies about his eyes, and uses CGI to make that color. Neil Degrasse Tyson comes to mind. He comes off as basking in his fame. Michio Kaku was my favorite science communicator growing up but I sadly don't see him. So I am glad others taken up the handle.
@@dianapennepacker6854 I have eyes that are easily as blue as steves, any number of colour grading settings with the right saturation and contrast will produce eyes that look that way, I don't think that means he's "lying" about anything, nor do I think it means he's "basking" in his "fame" (especially considering 1.17 Million is a pretty modest number on youtube nowadays and most people are fully aware of that) perhaps these are just the nicest looking settings for the room he's filming in? Would it be better if he released a youtube video where the lighting and colour grading are trash and we can barely make out what's happening?
Many pens are intended to be 'waterfast'. Once a mark is made on paper it is desirable to fix it there so presumably Bic will have some proprietary chemistry that bonds to the pigment/dye more aggressively than plain water and helps it resist spills and moisture once applied.
I was thinking something similar. You want your writing to dry as fast as possible, and the ink on water seemed dry. In fact you want large drops of ink to stay wet but thin sheets to dry fast. So there might be some sort of drying agent.
Yes, since the ink may be hydrophobic, it would resist the water and keep depositing itself to the already present ink in the water, causing a propulsion of sorts.
Hmm, I wonder if you could get the spread out ink to stick to paper and preserve the pattern in the same sort of way that dipped guitar bodies are made?
A similar thing happens if you get some tree sap on the end of a small stick and place it in water. It will move around and the left over sap will form a similarly brittle layer on the surface of the water.
@@hubrisnaut I used to do this in an area with lots of Tamaracks and other Pines. I'm not sure which species specifically we used, but we'd look for sap bubbles on the trunk and poke our little sticks into those to prepare them. Never tried with anything like a maple or other non-pine.
@@jaceive Balsam Fir (Abies balsamea) is the usual tree we use in Canada because it has blisters you can pop in the bark. We actually always called the activity "Balsam Boats" where I am from.
7:55 : "Maybe [...] something reacts with the water and becomes a hard surface that traps the dye". I believe that's what a polymer would do, which is likely added to the ink to give it the right viscosity. The phenoxyethanol acts as a plasticizer, but once it dissolves in the water, the polymer becomes hard. (And by the way, phenoxyethanol itself is somewhat of a surfactant. The hydroxyl moiety is somewhat hydrophilic, whereas the phenyl end is hydrophobic. So that would explain why it first rapidly spreads out, before it dissolves in the water.)
One pattern shows 4-fold symetry... Looks like a phase change (polymerization?) is going on resulting in dendritic crystal (and thus the hard surface?). Nice stuff, but likely several physics interacting...
Yes, you may be right. I do not know anything about the chemistry, but it looks like a very thin solid film is created, you can see it retaining its shape. This may explain why it breaks away in symmetric petals.
The polymer is probably the right answer here. That was my first guess, too. But I do think, that it doesn't need to react but rather precipitate from solution. This is quite easy to do. You simply need a mostly hydrophobic polymer that dissolves in the oleic acid and solvent mix. I'd think polycaprolactame or something similar might do. upon spreading on the surface, it simply precipitates from the mix and stays in that thin layer also binding the dye. A way to test this hypothesis would be to try to redissolve the thin layer in oleic acid and solvent again. If that's possible, it's not a reactive but a precipitative system. I think the type of polymer would be a company secret.
Really good teachers let us know when they have no idea what's actually going on, in contrast to all those snobs that make us all think we're dumb while they don't really know it better. Thanks Steve, very refreshing, propelled by curiosity, great!
Very fun !! As a marbler, I'm wondering if skimming the surface would reduce the surface tension for smoother trails. Surfactants used in marbling inks are Oxgall, Photo-Flo, Spirits of soap... We use aluminum sulphate as a mordant for the paper that captures the pattern. In case you want a hard copy of your experiments.
The fractal boundary on the wriggling blob around 4:28 is magnificent; it could just about be a Julia set illustration. I’d love to see some high-def magnified images of that.
I have actually done this experiment before by accident when i broke my ball pen and tried to clean it off in the sink with the water not drained, there i saw these shapes coming out from the drops of ink that fell on the water. I then decided to break another pen and played with it for an hour.
Hey steve, As a person with 10 years of experience sniffing pen, I can tell you that the effect is due to the fact that you're high. Those stuff you can sniff from the pen is good stuff, man. Alcohol pen, ballpoint, felt tip, you name it. Btw love your videos, I eat them everyday! edit: grammar
3:54 I was reminded of a Thunderf00t video, where he talks about coulombic explosions, and in his explanation he brings up a situation where the effective surface tension is negative, meaning that the two surfaces want to expand/maximise instead of shrinking. Seeing the two substances get more involved in eachother in that almost fractal looking way made me think of this.
One of my favorite things about you as a science educator is your willingness to say "I don't fully understand that yet." It really shows how humble and curious you are.
Steve, I think you are truly a modern day scientists much akin to those who have come before you. I'm talking like way back! They took something they thought was interesting, did their own experiments, researched what could be uncovered, and came to their own conclusions which they shared in a clear and concise way to the public. They didn't have any one area of expertise in particular, but rather were fascinated with the entire world around them and wanted to share that awe with others. Thanks for your videos! I always get excited when you show up in my feed!
Don't remember who the quote was originally from, but growing up I often heard from math and science teachers that "mathematics is the language of the universe/nature"
@@TheSphongleface there is a difference, dye can be used as a staining agent, but not all pigments can be used for staining. For staining, the pigment must be retained by the tissue to be stained.
@@TheSphongleface Dyes are soluble in the medium they're mixed with. Pigments are not, and remain as discrete particles. One can not be "made of" the other.
@@MysticalDork Just to nitpick, some dyes are made into pigments by forming a so-called "lake": fine particles of some carrier substance which are coloured by the dye.
@@kevinmartin7760 Not quite - lakes are insolvable calcium or aluminium salts (usually) of some acidic dyes. It’s not just adsorbing the dye onto a solid, but a reaction that produces an insoluble pigment product.
Might have to do with the pigment/dye particles being encapsulated by some of the other ingredients? It's apparently a common practice in the paint industry if I remember correctly.
As a kid, we used pine needles that we would poke in sap bubbles trapped underneath the bark of pines trees to make needle race boats. The movements and iridescent trail left behind was extremely similar.
Steve have you tried this with various types of water, like deionised, distilled, 'hard tap water' etc? It would be interesting to see if that makes any difference. I'd guess hard water will produce more restrained patterns than the others... Really interesting video as ever
@@wonderwang1585 growing up we got water from a well that was extremely soft, and it felt like soap never washed off. Lots of things can unexpectedly alter the properties of water in even tiny amounts it's always worth checking these things, if nothing else than to eliminate variables.
@@LeoStaley Exactly. The mineral (i.e. ion) content is extremely important. The soap felt like it didn't wash off because it didn't. Soap works because of the difference in polar/non-polar interactions. Pure water doesn't conduct electricity. Water with some salts does.
As kids, we used to do something similar with leaves or tiny sticks and spruce/fir gum. When put in water puddles, it propels the leaf as a little boat but also produce a shinny rainbow trail on the surface of the water.
I'm more intrigued by how staunch a blockade the ink became in the water after it provided propulsion. The equivalent of logs in a river to a boat. I was not expecting that.
Can we appreciate the fact Steve isn't afraid to say he doesn't fully understand? This is important to teach people as we don't have to always know everything. It's okay and important to normalise saying "I don't know" or "I don't understand".
I used to love doing this as a kid, I would watch the little blob of ink fly around the surface and then place paper on top of the water once there was a cool pattern, made tons of them.
I observed this effect when I was a young boy in the boundary waters. Certain pine cones, when dropped in the water, would be propelled by the oils/resins stored inside the pine cone. The trails it left looked like motor oil on a city street, that sort of rainbow effect anyways. Loads of renewable fun
Phenoxyethanol is amphiphilic, so it lowers the surface tension as well, that's probably also* why it spreads out in that particular way before it gets dissolved. To make the crust there needs to be a lipophilic component in the ink, which does not dissolve in the water, and the dyes themselves, being more lipophilic, stay with that residue. * Differences in concentration can lead to small but significant differences in pressure, osmotic pressure is a thing. And so just the process of dissolving something can induce flow. This is the other part of the explanation.
It’s trying to spread out as much as possible and have the highest possible surface area with the water, so it makes sense to me that it would often trend towards shapes that have infinite surface area (ie fractals)
Hi Steve. Thank you for bringing super cool scientific phenomena to my eyes. You are a great communicator and educator. Keep up the great work! Kieran from Scotland ;)
This reminds me of the old special effects technique of cloud tanks (think of Independance Day (when the alien ship emerges from the clouds), Star Trek's nebulae, The Ten Commandments or Ghostbusters final battle). I would suspect that there is some visual effects veteran who could easily answer all of your questions.
i think its oxydation part thats responsible for the crusty layer, rather than water reaction. id check the ink under water and limit access to air to see how it might react. i have to make myself similar setup to test it out, its looking nice, and similar to japanese ink art, and turkish ink art.
Oleic Acid is commonly used to disperse nanoparticles in organic solvents. My guess is that the ink particles have been covered in Oleic acid with the hydrophobic group facing outwards. This would make them hydrophobic and prevent them from dissolving in the water.
@steve mould - happy to point you to some protocols but generally you just need a sonicator to get the particles into suspension so that they can coordinate fully with the acid groups. I would not be surprised if this is how the ink was made in the first place...
Seems to me like the phenoxyethanol is dissolving into the water just like it is on its own, causing the propulsion due to a change in surface tension, but I think the reason for the different behaviour when it is the pen ink is that the pigment is left behind on the surface of the water. You can see that it forms these solid rafts on the surface and causes somewhat ot an additional resistance in the process. It somewhat reminds me of the way the Pharaoh's Serpent experiment or the little fireworks "snakes" work, that perpetually grow from releasing a more solid or voluminous residue when burning a more dense material as a source. It looks like the same is happening here, with the solvent keeping the pigment bunched up but upon dissolving into the water, the pigments forms this thin layer on the surface and takes up a lot more room as these rafts that the propulsion caused by the dissolving phenoxyethanol is pushing against. In one of the shots you can even see the leaf being stopped by running into one of these pigment-rafts, so there has to be some resistance enough to cause a different effect.
3:22 Seeing Steve sniffing ballpoint pen solvent gave me (and likely every Boomer) flashbacks of receiving a test in high school fresh off the mimeograph machine and everybody sniffing the acetone solvent still evaporating off the paper.
7:41 Ball-point ink is usually quite waterfast. Doesn't run on wet paper. So this behaviour makes sense. Not weird at all. Another additive to the ink you're not aware of stabilises the pigment emulsion.
As children we had this locally popular game of tiny boat racing: you get a fir tree needle, then you dip its end into a bump on a fir tree bark (they are full of resin) and then you just put that needle onto the water surface. The resin acts exactly the same way (and as far as I remember, better) how your ink does and propels those needles very fast. So basically just launched those needles in ponds, trying to reach the other end of the pond as fast as possible. Instead of fir needles we used a whole bunch of other random stuff that floats too: tiny wooden carved boats/ships, sawdust chips, matches, even metallic needles work if you manage to put one onto the water surface (held by surface tension, I experimented with those in a tub). However, of all natural resins that we tried, fir resin is the only one that worked really well, probably because it has quite low viscosity. As a side note, in your experiment with red ink you can see a darker spot forming on the water close to the leaf. With resin, however, you can clearly see it's actually an interference pattern that creates a rainbow-like oil film interference pattern that sort of looks like flame ejected from a rocket nozzle that makes the resin trail look so much cooler. After launching 3-5 boats in small pond its entire surface gets covered by the oil film and no further boats could be launched there. I was kind of jealous how phenoxyethanol that you demonstrated dissolves into the water allowing more boats to be launched.
Surface tension is not the main issue. Most solvents we'll float on water because they are lighter than water the main point of the ink and the other things that you're putting on top of the water is they are being diluted by the water and they spread out to cover the top of the water because they are finding the lowest level as far as they will stay together get down to one layer of molecules
I work in a research laboratory and i've witnessed this weird pearly sparkling phenomena many times with just pure ethanol mixing in water. (We sometimes clean things like grinding mills etc. with water and ethanol) I'd love to see some deep explanation to this phenomeon!
I think you should do another test, but first load the water pool with a lot of surfactant/detergent/soap so that the surface tension of the water is incredibly weak, too weak for the soap raft experiment to work anymore. If we see little to no movement from an ink raft then we know the process is driven by surface tension. It's even possible that if you weaken the surface tension of the water enough then the leaf may move backwards as the ink's relatively stronger surface tension is "grabbing" the water.
Hi Steve - on a similar note, I always wondered what causes the tendril like spreading of ink blots on wet paper. This video reminded me of that - would love to see a video on that topic.
One of the most captivating observations in my research is to study reactions similar to this under a microscope, I could watch this for hours at a time. So my interpretation of this is, when the alcohol or whatever other ingredients of the ink come into contact with the water, they evaporate the gasses are captured in an expanding microscopic foam, resulting in the leaf being propelled away from this expansion, and the increase of surface area of the trailing ink.
There is an important difference between a dye and a pigment. Dyes are soluble in solvents whereas pigments are solid particles carried by and dispersed in the ink. You mentioned carbon black at the start of the video, that's an insoluble powder. So the pigment is being dispersed onto the water, but eventually the carrier solvent phenoxyethanol dissolves into the water leaving a rigid raft of pigment. The initial dispersal is driven, I believe by the added surfactants. The surfactants dissolve readily in the water and dissipates.
I noticed this when I was a kid in elementary school. I would take the end out of the ink cartridge in a pen and put it in the drains on the side of the streets when it rained and watched it race forward
I used to do this as a kid. I was not the most studious but I was curious, so what I would do is on rainy days go to puddles near my house and bite the tip off a pen and blow a dot of ink out and instead of putting it on a leaf I'd but the whole ink tube on water and watch it being propelled like a rocket 🚀. Ah childhood was a good time. Great video though, we didn't have internet back then so I didn't know how it worked and so it was interesting to see something from my childhood being explained in a scientific manner and gaining an understanding of what I've experienced.
Whats intresting is that the die in the water seems to have form a kind of solid form. Extremly fragile but if you look at the interactions from the leave with the ink trails you can see that it actually forms up some resistance towards it instead of just breaking apart.
I think you should use a thermal camera to see thermal expansion. My guess is there’s also a small amount of heat being generated. Or I would also use solar lenses to check and see what stresses are being applied to the leaf medium.
Love your videos Steve. They're interesting and easy to follow. While watching this one I was wondering if gravity works as a soap lowering the surface tension of SpaceTime.
Out of gratitude for their sponsorship I listen to your self produced advertisements for your corporate supporters instead of three taps till it’s over. Weird. Love your work.
There could be some polymer dissolved in the ink to tune viscosity, stickiness or whatever. It's probably insoluble in water. When it touches the water it crashes out and traps the dye/pigment inside. The changing surface tension then pulls it into a thin layer.
Some food for thought: -Liquid soap is mostly water or some other liquid that isn't breaking the surface tension, if it was purely a surfactant or something else that messes with the surface tension it'd be much stronger and behave much more radical effect with the surface tension and how it spreads. Similar to what we see in the ink. -it is possible that the dye in the ink is more soluble in the ink than it is in water, and the solvent is radically more soluble in water than the pigment. The effect of how the pigment falls out of solution when the solvent is "sucked up" should be inspected.
When i was a kid we used to do this with sticks and the sap from balsam firs. Pop a bubble of sap on the bark with a stick and drop the stick in still water. Leaves a rainbow sheen similar to gasoline on water
I am a chemist and worked in industry making various products. The ink must contain at least 3 ingredients the solvent the pigment and a binder such as Carnauba wax which is why the ink goes hard after the solvent has been released.
One of the ingredients is a sealant, and reacts with water to cure. This is to keep ink from bleeding or blurring in humid or wet conditions. I imagine this is what makes the ink solid on the water surface.
During my tenure as a teenage delinquent street artist we used to make some really nasty ink by getting a box of biros, stripping the ink tubes out of them and then leaving them in brake fluid to dissolve. We'd then make what was called a mop out of an empty roll-on deodorant tube which you'd popped the ball out of and replaced with a dish sponge after filling the tube with the ink. The stuff could etch itself so deeply into concrete that you'd have to chip it off to remove the tags, if you painted over it it would just keep bleeding through endlessly. If you got it on your skin it'd take months to get rid of the stain and it'd never come out of clothes
My old journals, written in Bic ballpoint, have a greesy looking halo around the ink trace. The paper is yellowed and translucent for a few millimeters in every direction. I like fountain pens too and sometimes used those and they do not seem to have the ink spreading through the paper problem.
Dyes and pigments are different in a way that dyes dissolve in water / solvent, while pigment remains in it "crushed" particulate state. Maybe the combination of lubricant and powdered pigment is what causes the hard film residue on the surface.
Commercial inks contain a shellacing agent to protect the pigment particles. The pigment isn’t dissolved in ink, but dispersed. That’s one of the main differences between a pigment and a dye, as the dye is dissolved in the fluid medium. The dye physically bonds to the paper fibers, pigments don’t. I believe the sheeting you’re seeing is the shellacing agent.
The behavior of the phenoxy ethanol at 4:15 looks to be a much slower version of the dissolution at 3:53. Maybe this is because it was "corraled" by the other things on the surface. Either process looks like the chemical dissolution is maximizing it's perimeter to surface area or volume. Hence the fractal spikiness.
Regarding pure vs dilute oleic acid forming a blob vs a thin film, I think the surface tension of the pure oleic acid keeps it together whereas the dilute oleic acid solution has a surface tension vanishingly close to pure water. Once the dilute oleic acid is spread out, the "friction" to re-agglomerate is too high.
The crusty nature of the pen looks important. The way it is holding together, reminds me of a focused exhaust. This factor reduces the amount of surface spreading wasted on expanding to both sides.
Seems to me that the propulsion is being driven by the phenoxyethanol, and the reason that that the ink is forming rafts rather than just dispersing in the water is because it's mixed with the oleic acid which appears to be hydrophobic.
Cool video, and a cool demonstration to do with kids. Might be worth hitting up a pen ink manufacturer. They might be will to work with you for some publicity.
Might also be the order of blending. The dye molecules are coated with the oleic acid, making them insoluble in general, then coated with the solvent, to form small ink granules, that then will float on the top, bonded together by being non polar molecules in a thin sheet, and floating on the ionic liquid. Thus the need for a surfactant that allows the tiny ink granules to be broken, when shear mixing occurs in the ball tip, so they will be able to adhere to the paper when the solvent finally does evaporate.
The physicochemical properties of the dye can change dramatically if you don't have the exact same formulation. E.g. if the particle size is different or the commercial stuff has a surface bonded molecule to help it stay suspended
The most logical answer to me is that there's probably an additive such as grease or wax that makes it form that type of a coating. Since we're dealing with Phenoxyethanol, these cheap and easy to come by ingredients would be soluble and therefor have a different viscosity. Once the Phenoxyethanol evaporates, these additives then change back into their original state. Combined with the cooler temperature of the water, it's easy to understand why the "crusty" coating would form.
The number of takes I had to throw away because I had ink on my face!
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Action labs made a few videos about the effect I think is happening. He says low viscosity meeting high viscosity creates flow.
I wasn't disappointed to see no blue tongue or some other temporary tattoos from the ink :) If you ever do a blooper vod one day, please include!
Please make a video about egg + leaf + water, and then tell us how many takes you had to throw away because...
Walter Lewin sir's channel is going to be deleted because of some Glitch( not exactly).plss help him if you can.He is old He has 1 million subscribers.His channel is his life .He might loose all of his work
Plssss
Hey Steve,
I'm a Nanotechnology Engineer that has a little bit or perspective to share as this kinda sits right on the border between the chemistry and physics that I work with every day.
First and foremost, the propulsion you are seeing is definitely as a result of that difference in surface tension you mentioned. In fact this particular propulsion method is used a lot in various fields and usually the forces involved are referred to as Marangoni forces (because they arise from the Marangoni effect). Second, the way the ink spreads out actually screams that there is some surfactant and some phenoxy ethanol, and this is actually counter to one of the points you mentioned. You suggested that if a surfactant was present, the ink layer would break up into smaller pieces which can actually be seen on the outer edges of the trails in your videos. There often appears to be fractures with no external causal force. The other thing is that the pieces then appear to "bounce" away from one another despite neither piece involved in a collision being moving all that quickly. Altogether though there is some interesting Materials Science and fluid mechanics going on here and I'm excited about any follow up videos you make on the subject
Cheers
i would love to here more abour ur field sounds very intresting im going into higher education and thinking of majoring in chem and physics
What is this propulsion method used for? Sounds super interesting!
Hey Steve. Reach out to this guy. 😎
@@moikkis65 A lot of the applications are actually eerily similar to what is shown in the video. Mainly the creation of microswimmers, small pieces of material that move along the surface of water or another liquid. See papers 1 and 2 for more, but one of the other cool things about this is that the surface tension of water changes with temperature so you can actually use heat to trigger this effect. These are called thermal Marangoni effects, while the others are called solutal ones, because they are caused by a solute, something dissolved in the water or other liquid. Thermal Marangoni effect are quite common in situations where there is some kind of local heating such as welding (See paper 3) and crystal growth (see paper 4). The biggest one by far though is using this to clean silicon that is used in electronics manufacturing. Currently manufacturers are working on the scale of approximately 24 nm which is about 1/3000 th the width of a human hair. As a result if even so much as one dust particle or salt spot is on the surface this can lead to a device being defective. To clean the materials used, alcohol is sprayed at a wet surface, which causes one side of the droplets of water to have a lower surface tension and so they are propelled off of the surface similar to how the leaf is propelled on the surface of the water. (See paper 5.)
In summary though, many applications are still only in the lab. That said, many of these may start popping up in unexpected places as technology gets more advanced and our control of chemistry goes down to smaller and smaller scales.
See these papers:
www.nature.com/articles/s41467-021-24996-8
www.nature.com/articles/s41467-019-11141-9
www.sciencedirect.com/science/article/pii/S0921509308001603
doi.org/10.1002/(SICI)1521-4079(199904)34:4%3C457::AID-CRAT457%3E3.0.CO;2-6
pubs.acs.org/doi/pdf/10.1021/la00101a014?casa_token=KCFCgXMmPm4AAAAA:Pr4Io9ornnnSk9VY4izWmcEhZivOdojBMcas0O9IqD1rpfUXivhfeJbwuVLivLnJv4bKYciBW78YHf4
@@reesemartens759 thank you so much that is indeed way cooler than I thought it would be :o
The fractal nature of the ink was the most shocking part to me. I couldn't help but imagine a blossoming flower every single time that leaf boat started up. Really interesting stuff Steve.
The fractals forming in the footage at 4:15 were mesmerizing. Really would like a close-up of that
Never be shocked by the fractal nature of things. This was awesome.
maximum boundry length ftw :D
@@paouboy but... Limitless boundary length?
it forming fractals means that it had negative surface tension im pretty sure. positive surface tension minimizes surface area by forming round droplets, so the only way it could be maximizing its surface area is if the opposite were true
As an ink developer (but not the kind of a writing pen), I'd say this is perfectly normal and we see it everyday in lab. First of all, solvents used in inks generally have low surface tension to facilitate the wetting of ink on substrates and might help the transfer of ink from the tip of pen onto paper though I'm not sure in that. The low surface tension first causes the spreading of the ink on water, which is a high surface tension substrate. Most solvents are also immiscible with water and have lower density, which makes them stay separated from water and float on top. On the second fact, the pigments usually require anchoring agents/dispersant/surfactants or whatever you call it, to help them disperse in solvents with high stability and long lasting manner. Pigments and dyes used in inks may also poorly disperse in water which prevents them from "dissolving into the water" as in the video. The last fact is that we use various kinds of polymers to give functions to the inks, such as the shininess, water resistance or other desirable mechanical properties. These polymers generally don't dissolve well in water and forms a rigid solid film when the solvent carrier dries away.
In sum, the solvent properties (low surface tension, viscosity, immiscibility with water) causes the spreading of the ink on top, and the pigment or dye used in the ink are chemically modified to improve dispersibility in the solvent and prevents them from coagulating/sinking/dissolving into water. Lastly as the solvents evaporates, the polymers in the ink solidifies and what's left behind is a film of water-insoluble polymer, holding pigment or dye molecules that were dispersed in the solvent.
Any Ideas on where I can get these ingredients? I have some Ideas for artistic purposes.
I was wondering if the dye in the ink wasn't some sort of plastic, but chemically set rather than thermally.
Very smart
@@natebell4764 Hi Nate, I think you can probably order the resins or colorants online, but I am not sure of your local regulations whether those would be counted as danger or restricted chemicals so beware. Solvent Red, solvent blue, solvent black might be what you are looking for. Resins, there are so many types available and I don't know which type would suit your purpose. You can contact the suppliers and see what types they could offer. In general, acrylic resins/cellulose acetates or vinyl copolymers would be something that we use most of the times that are water insoluble and fast film forming. The last problem is the solvent, which are usually dangerous goods as they are mostly flammable, and you might not be able to get them in large volume. However, you may first try something like paint thinner, which is essentially mixture of organic solvents that is usually compatible with many resins and are immiscible with water.
@DeadlyPlatypus Yes, that's also true. Resins and colorants in inks, whether organic or inorganic, are usually "deposited" onto the substrate and form films when solvents dry away. Imagine you dissolve high concentration of sugar into water, brush the solution on some surface and wait for it to dry, which then you will get a dried film that is not thermally set but rather a physically deposited and slightly chemically set layer of sugar molecules.
What I like about this channel better than other science channels is that he asks us questions and shares his investigation process, instead of just giving us facts and answers.
Method is the definition of "Science"
Arts and Sciences.
I sincerely love hearing, "I don't really know why it does that," in this video. It sort of emphasizes that you can pursue a general understanding of a scientific phenomenon to a satisfactory degree without necessarily ruining the mystery of it.
I latched onto that sentence as well. It made me realize, along with his chain fountain series, that Steve is one of the few TH-camrs I watch that conducts original experiments and shares his findings rather than just summarizing what he reads online. Don't get me wrong, I like the channels that summarize difficult concepts to make them easier for the masses to understand as well, but it's amazing to see the lengths Steve will go just to learn about the world around him, whether or not someone else has already done the research before him. I also like that he doesn't need an EXACT answer before posting a video. He is willing to get partial information out there just to spur interest and conversation. It makes me feel like I am actually witnessing discoveries happening today rather than learning about something historical.
Steve Mold is an honest man which makes him great. I am sure though he lies about his eyes, and uses CGI to make that color.
Neil Degrasse Tyson comes to mind. He comes off as basking in his fame.
Michio Kaku was my favorite science communicator growing up but I sadly don't see him. So I am glad others taken up the handle.
@@dianapennepacker6854 I have eyes that are easily as blue as steves, any number of colour grading settings with the right saturation and contrast will produce eyes that look that way, I don't think that means he's "lying" about anything, nor do I think it means he's "basking" in his "fame" (especially considering 1.17 Million is a pretty modest number on youtube nowadays and most people are fully aware of that) perhaps these are just the nicest looking settings for the room he's filming in? Would it be better if he released a youtube video where the lighting and colour grading are trash and we can barely make out what's happening?
It's just a brief moment of nice curiosity.
@@4bidn1 I was joking mate.
Many pens are intended to be 'waterfast'.
Once a mark is made on paper it is desirable to fix it there so presumably Bic will have some proprietary chemistry that bonds to the pigment/dye more aggressively than plain water and helps it resist spills and moisture once applied.
I was thinking something similar. You want your writing to dry as fast as possible, and the ink on water seemed dry. In fact you want large drops of ink to stay wet but thin sheets to dry fast. So there might be some sort of drying agent.
@@freedomcaller
Thats the alcohol part.
Yes, since the ink may be hydrophobic, it would resist the water and keep depositing itself to the already present ink in the water, causing a propulsion of sorts.
Hmm, I wonder if you could get the spread out ink to stick to paper and preserve the pattern in the same sort of way that dipped guitar bodies are made?
Gonna hold off until I hear from ElectroBoom.
Damn, is that how it's going to be from now on?
@@SteveMould haha if you guys push and pull each other then why not.
Fun for everyone 😂.
@@SteveMould Yes.
@@trevorcarl9515 I really hope not.
@@SteveMould lol yes please
A similar thing happens if you get some tree sap on the end of a small stick and place it in water. It will move around and the left over sap will form a similarly brittle layer on the surface of the water.
I did this a lot as a kid! Racing twigs was a good way to burn time after rainy days!
Hi, I am very curious about what kind of tree sap does this? Conifers like pine or any sap?
@@hubrisnaut I used to do this in an area with lots of Tamaracks and other Pines. I'm not sure which species specifically we used, but we'd look for sap bubbles on the trunk and poke our little sticks into those to prepare them. Never tried with anything like a maple or other non-pine.
I came here to say this. I always thought it was the same process.
@@jaceive Balsam Fir (Abies balsamea) is the usual tree we use in Canada because it has blisters you can pop in the bark. We actually always called the activity "Balsam Boats" where I am from.
7:55 : "Maybe [...] something reacts with the water and becomes a hard surface that traps the dye".
I believe that's what a polymer would do, which is likely added to the ink to give it the right viscosity. The phenoxyethanol acts as a plasticizer, but once it dissolves in the water, the polymer becomes hard.
(And by the way, phenoxyethanol itself is somewhat of a surfactant. The hydroxyl moiety is somewhat hydrophilic, whereas the phenyl end is hydrophobic. So that would explain why it first rapidly spreads out, before it dissolves in the water.)
One pattern shows 4-fold symetry... Looks like a phase change (polymerization?) is going on resulting in dendritic crystal (and thus the hard surface?). Nice stuff, but likely several physics interacting...
Also it is possible that the film polymerizes after it contacts with the air above.
Yes, you may be right. I do not know anything about the chemistry, but it looks like a very thin solid film is created, you can see it retaining its shape. This may explain why it breaks away in symmetric petals.
The polymer is probably the right answer here. That was my first guess, too. But I do think, that it doesn't need to react but rather precipitate from solution. This is quite easy to do. You simply need a mostly hydrophobic polymer that dissolves in the oleic acid and solvent mix. I'd think polycaprolactame or something similar might do. upon spreading on the surface, it simply precipitates from the mix and stays in that thin layer also binding the dye.
A way to test this hypothesis would be to try to redissolve the thin layer in oleic acid and solvent again. If that's possible, it's not a reactive but a precipitative system. I think the type of polymer would be a company secret.
Really good teachers let us know when they have no idea what's actually going on, in contrast to all those snobs that make us all think we're dumb while they don't really know it better. Thanks Steve, very refreshing, propelled by curiosity, great!
Very fun !!
As a marbler, I'm wondering if skimming the surface would reduce the surface tension for smoother
trails.
Surfactants used in marbling inks are Oxgall, Photo-Flo, Spirits of soap...
We use aluminum sulphate as a mordant for the paper that captures the pattern.
In case you want a hard copy of your experiments.
The fractal boundary on the wriggling blob around 4:28 is magnificent; it could just about be a Julia set illustration. I’d love to see some high-def magnified images of that.
I NEED high def footage of that. When I saw it I just about jumped out of my chair!
And slo-mo
Interesting observation + good videography and demonstration + clear and easy to follow explanation = Great Video!
+ That Voice
@@Uncreeperble + Big Blue Eyes
I have actually done this experiment before by accident when i broke my ball pen and tried to clean it off in the sink with the water not drained, there i saw these shapes coming out from the drops of ink that fell on the water. I then decided to break another pen and played with it for an hour.
And you failed....
Hey steve,
As a person with 10 years of experience sniffing pen, I can tell you that the effect is due to the fact that you're high. Those stuff you can sniff from the pen is good stuff, man. Alcohol pen, ballpoint, felt tip, you name it. Btw love your videos, I eat them everyday!
edit: grammar
3:54 I was reminded of a Thunderf00t video, where he talks about coulombic explosions, and in his explanation he brings up a situation where the effective surface tension is negative, meaning that the two surfaces want to expand/maximise instead of shrinking. Seeing the two substances get more involved in eachother in that almost fractal looking way made me think of this.
One of my favorite things about you as a science educator is your willingness to say "I don't fully understand that yet." It really shows how humble and curious you are.
That footage of phenoxyethanol on water at 3:54 immediately reminded me of sped up and zoomed out footage of Conway's Game of Life.
Yes. And maybe the driving forces are similar; i.e., for any small region, how many nearby regions have high or low concentrations...
Whoa, they made Conway's game of life into a real thing!
@@vigilantcosmicpenguin8721 Wow they made the game of life in real life*
@@nicobugs "what was that noise?"
The joke
Steve, I think you are truly a modern day scientists much akin to those who have come before you. I'm talking like way back! They took something they thought was interesting, did their own experiments, researched what could be uncovered, and came to their own conclusions which they shared in a clear and concise way to the public. They didn't have any one area of expertise in particular, but rather were fascinated with the entire world around them and wanted to share that awe with others.
Thanks for your videos! I always get excited when you show up in my feed!
when the phenoxyethanol dissolves in the water, it looks like fractals. Pretty cool, math and nature go hand in hand.
Don't remember who the quote was originally from, but growing up I often heard from math and science teachers that "mathematics is the language of the universe/nature"
I came here to say just that. Now I want an explanation of that!
A mandel blot? ;)
I was wondering, if you gently lay a piece of paper on top, would the ink transfer to it ? You could get some nice pictures that way.
@sprock it looked like it repeated it self many times, which reminded me a lot of a fractal
Strictly speaking, carbon black is a pigment, while eosin (pronounced ee-o-sin) is a dye.
Appreciate the correction
@@TheSphongleface there is a difference, dye can be used as a staining agent, but not all pigments can be used for staining.
For staining, the pigment must be retained by the tissue to be stained.
@@TheSphongleface Dyes are soluble in the medium they're mixed with. Pigments are not, and remain as discrete particles. One can not be "made of" the other.
@@MysticalDork Just to nitpick, some dyes are made into pigments by forming a so-called "lake": fine particles of some carrier substance which are coloured by the dye.
@@kevinmartin7760 Not quite - lakes are insolvable calcium or aluminium salts (usually) of some acidic dyes. It’s not just adsorbing the dye onto a solid, but a reaction that produces an insoluble pigment product.
Might have to do with the pigment/dye particles being encapsulated by some of the other ingredients? It's apparently a common practice in the paint industry if I remember correctly.
Interesting!
Like a micelle?
@@SteveMould I love your sarcasm makes the learning much more interesting XD
As a kid, we used pine needles that we would poke in sap bubbles trapped underneath the bark of pines trees to make needle race boats. The movements and iridescent trail left behind was extremely similar.
Steve have you tried this with various types of water, like deionised, distilled, 'hard tap water' etc? It would be interesting to see if that makes any difference. I'd guess hard water will produce more restrained patterns than the others...
Really interesting video as ever
Hydrogen bond is not degrade easily. So the impurity suppose to have little impact presumably.
@@wonderwang1585 growing up we got water from a well that was extremely soft, and it felt like soap never washed off. Lots of things can unexpectedly alter the properties of water in even tiny amounts it's always worth checking these things, if nothing else than to eliminate variables.
@@LeoStaley Exactly.
The mineral (i.e. ion) content is extremely important. The soap felt like it didn't wash off because it didn't. Soap works because of the difference in polar/non-polar interactions.
Pure water doesn't conduct electricity. Water with some salts does.
As kids, we used to do something similar with leaves or tiny sticks and spruce/fir gum. When put in water puddles, it propels the leaf as a little boat but also produce a shinny rainbow trail on the surface of the water.
I'm more intrigued by how staunch a blockade the ink became in the water after it provided propulsion. The equivalent of logs in a river to a boat. I was not expecting that.
Good point
@@SteveMould You just made my day! Keep up the great work.
Can we appreciate the fact Steve isn't afraid to say he doesn't fully understand? This is important to teach people as we don't have to always know everything. It's okay and important to normalise saying "I don't know" or "I don't understand".
"Half Tau" day really got me! hahahaha
ಠ_ಠ
Wow!..an amazing demonstration of the energy released during the breakdown of individual molecular structures!…thanks for sharing
4:00 would look wicked in slow-motion + macro lens! Someone get in touch with Slow Mo Guys
THIS. OMG THIS.
This made me emotional. The chemistry and our universe is so beautiful. Fractal nature.
What a cool way to show the physics behind saturation and expansion during absorption. Awesome video!!
I used to love doing this as a kid, I would watch the little blob of ink fly around the surface and then place paper on top of the water once there was a cool pattern, made tons of them.
I observed this effect when I was a young boy in the boundary waters. Certain pine cones, when dropped in the water, would be propelled by the oils/resins stored inside the pine cone. The trails it left looked like motor oil on a city street, that sort of rainbow effect anyways. Loads of renewable fun
Phenoxyethanol is amphiphilic, so it lowers the surface tension as well, that's probably also* why it spreads out in that particular way before it gets dissolved. To make the crust there needs to be a lipophilic component in the ink, which does not dissolve in the water, and the dyes themselves, being more lipophilic, stay with that residue.
* Differences in concentration can lead to small but significant differences in pressure, osmotic pressure is a thing. And so just the process of dissolving something can induce flow. This is the other part of the explanation.
4:23 that straight up looked like a perfect mandelbrot fractal
It’s trying to spread out as much as possible and have the highest possible surface area with the water, so it makes sense to me that it would often trend towards shapes that have infinite surface area (ie fractals)
More like a Julia fractal, but indeed my first thought as well
Love that timestamp. I'm constantly clicking it
I love how science can show me crazy new things all the time. I love these kinds of little experiments and finding out the mechanics of it!
The things you cover are so fascinating to me that it almost hurts.
What a wonderful world this is.
Hi Steve. Thank you for bringing super cool scientific phenomena to my eyes. You are a great communicator and educator. Keep up the great work!
Kieran from Scotland ;)
This is really, really cool. Great video Steve, I'm looking forward to seeing more on this.
This reminds me of the old special effects technique of cloud tanks (think of Independance Day (when the alien ship emerges from the clouds), Star Trek's nebulae, The Ten Commandments or Ghostbusters final battle). I would suspect that there is some visual effects veteran who could easily answer all of your questions.
Hi Steve,
I’m a store man and I loved the video. You made a normal man feel like a scientist.
3:21 was so funny and exactly the vibe of why I subbed
i think its oxydation part thats responsible for the crusty layer, rather than water reaction. id check the ink under water and limit access to air to see how it might react.
i have to make myself similar setup to test it out, its looking nice, and similar to japanese ink art, and turkish ink art.
That shot at 7:24 is a work of art!
Oleic Acid is commonly used to disperse nanoparticles in organic solvents. My guess is that the ink particles have been covered in Oleic acid with the hydrophobic group facing outwards. This would make them hydrophobic and prevent them from dissolving in the water.
@steve mould - happy to point you to some protocols but generally you just need a sonicator to get the particles into suspension so that they can coordinate fully with the acid groups. I would not be surprised if this is how the ink was made in the first place...
Ink Powerer Leaf gang. I was here before the typo correction (at least, I assume it's going to be corrected) in the thumbnail.
Steve opening a new can of worms to have inter-youtuber debates for another few months lol
but it is a healthy way to learn.
@@peterkelley6344 Oh yeah I'm all for it😂 More content for us to watch
Seems to me like the phenoxyethanol is dissolving into the water just like it is on its own, causing the propulsion due to a change in surface tension, but I think the reason for the different behaviour when it is the pen ink is that the pigment is left behind on the surface of the water. You can see that it forms these solid rafts on the surface and causes somewhat ot an additional resistance in the process. It somewhat reminds me of the way the Pharaoh's Serpent experiment or the little fireworks "snakes" work, that perpetually grow from releasing a more solid or voluminous residue when burning a more dense material as a source. It looks like the same is happening here, with the solvent keeping the pigment bunched up but upon dissolving into the water, the pigments forms this thin layer on the surface and takes up a lot more room as these rafts that the propulsion caused by the dissolving phenoxyethanol is pushing against. In one of the shots you can even see the leaf being stopped by running into one of these pigment-rafts, so there has to be some resistance enough to cause a different effect.
3:22 Seeing Steve sniffing ballpoint pen solvent gave me (and likely every Boomer) flashbacks of receiving a test in high school fresh off the mimeograph machine and everybody sniffing the acetone solvent still evaporating off the paper.
7:41 Ball-point ink is usually quite waterfast. Doesn't run on wet paper. So this behaviour makes sense. Not weird at all. Another additive to the ink you're not aware of stabilises the pigment emulsion.
The spreading ink "boats" produce some really cool art works. Well worth putting on paper and hanging on a wall.
As children we had this locally popular game of tiny boat racing: you get a fir tree needle, then you dip its end into a bump on a fir tree bark (they are full of resin) and then you just put that needle onto the water surface. The resin acts exactly the same way (and as far as I remember, better) how your ink does and propels those needles very fast. So basically just launched those needles in ponds, trying to reach the other end of the pond as fast as possible.
Instead of fir needles we used a whole bunch of other random stuff that floats too: tiny wooden carved boats/ships, sawdust chips, matches, even metallic needles work if you manage to put one onto the water surface (held by surface tension, I experimented with those in a tub). However, of all natural resins that we tried, fir resin is the only one that worked really well, probably because it has quite low viscosity.
As a side note, in your experiment with red ink you can see a darker spot forming on the water close to the leaf. With resin, however, you can clearly see it's actually an interference pattern that creates a rainbow-like oil film interference pattern that sort of looks like flame ejected from a rocket nozzle that makes the resin trail look so much cooler.
After launching 3-5 boats in small pond its entire surface gets covered by the oil film and no further boats could be launched there. I was kind of jealous how phenoxyethanol that you demonstrated dissolves into the water allowing more boats to be launched.
Surface tension is not the main issue. Most solvents we'll float on water because they are lighter than water the main point of the ink and the other things that you're putting on top of the water is they are being diluted by the water and they spread out to cover the top of the water because they are finding the lowest level as far as they will stay together get down to one layer of molecules
4:18 looks like Marangoni forces! They look like something you might LOVE
If you hydrodipped some paper into that inked water you could make some serious money on the art it would produce!
I work in a research laboratory and i've witnessed this weird pearly sparkling phenomena many times with just pure ethanol mixing in water. (We sometimes clean things like grinding mills etc. with water and ethanol) I'd love to see some deep explanation to this phenomeon!
I think you should do another test, but first load the water pool with a lot of surfactant/detergent/soap so that the surface tension of the water is incredibly weak, too weak for the soap raft experiment to work anymore. If we see little to no movement from an ink raft then we know the process is driven by surface tension. It's even possible that if you weaken the surface tension of the water enough then the leaf may move backwards as the ink's relatively stronger surface tension is "grabbing" the water.
Yes this^^^^
This is a great video. I love how much we still don’t know. It shows how the questions of science keep growing the more we look.
I remember at secondary school, I kicked an open bottle of nail varnish and it went into the school pond. It then propelled itself to the other side
Hi Steve - on a similar note, I always wondered what causes the tendril like spreading of ink blots on wet paper. This video reminded me of that - would love to see a video on that topic.
One of the most captivating observations in my research is to study reactions similar to this under a microscope, I could watch this for hours at a time. So my interpretation of this is, when the alcohol or whatever other ingredients of the ink come into contact with the water, they evaporate the gasses are captured in an expanding microscopic foam, resulting in the leaf being propelled away from this expansion, and the increase of surface area of the trailing ink.
There is an important difference between a dye and a pigment. Dyes are soluble in solvents whereas pigments are solid particles carried by and dispersed in the ink.
You mentioned carbon black at the start of the video, that's an insoluble powder. So the pigment is being dispersed onto the water, but eventually the carrier solvent phenoxyethanol dissolves into the water leaving a rigid raft of pigment. The initial dispersal is driven, I believe by the added surfactants. The surfactants dissolve readily in the water and dissipates.
I noticed this when I was a kid in elementary school. I would take the end out of the ink cartridge in a pen and put it in the drains on the side of the streets when it rained and watched it race forward
I used to do this as a kid. I was not the most studious but I was curious, so what I would do is on rainy days go to puddles near my house and bite the tip off a pen and blow a dot of ink out and instead of putting it on a leaf I'd but the whole ink tube on water and watch it being propelled like a rocket 🚀. Ah childhood was a good time. Great video though, we didn't have internet back then so I didn't know how it worked and so it was interesting to see something from my childhood being explained in a scientific manner and gaining an understanding of what I've experienced.
Whats intresting is that the die in the water seems to have form a kind of solid form. Extremly fragile but if you look at the interactions from the leave with the ink trails you can see that it actually forms up some resistance towards it instead of just breaking apart.
I think you should use a thermal camera to see thermal expansion. My guess is there’s also a small amount of heat being generated. Or I would also use solar lenses to check and see what stresses are being applied to the leaf medium.
Love your videos Steve. They're interesting and easy to follow. While watching this one I was wondering if gravity works as a soap lowering the surface tension of SpaceTime.
Man, I would love to see a Slow Mo Guys episode on this. Or better yet, a collaboration with Steve and Gavin!
It is good to know there are people out there asking all the big questions.
Out of gratitude for their sponsorship I listen to your self produced advertisements for your corporate supporters instead of three taps till it’s over. Weird. Love your work.
unironically love how this guy just goes "idk what's happening" like yeah dude me neither and that's ok
There could be some polymer dissolved in the ink to tune viscosity, stickiness or whatever. It's probably insoluble in water. When it touches the water it crashes out and traps the dye/pigment inside. The changing surface tension then pulls it into a thin layer.
Some food for thought:
-Liquid soap is mostly water or some other liquid that isn't breaking the surface tension, if it was purely a surfactant or something else that messes with the surface tension it'd be much stronger and behave much more radical effect with the surface tension and how it spreads. Similar to what we see in the ink.
-it is possible that the dye in the ink is more soluble in the ink than it is in water, and the solvent is radically more soluble in water than the pigment. The effect of how the pigment falls out of solution when the solvent is "sucked up" should be inspected.
When i was a kid we used to do this with sticks and the sap from balsam firs. Pop a bubble of sap on the bark with a stick and drop the stick in still water. Leaves a rainbow sheen similar to gasoline on water
The patterns are cool and look like fractals, specially this one here: 3:54
I am a chemist and worked in industry making various products. The ink must contain at least 3 ingredients the solvent the pigment and a binder such as Carnauba wax which is why the ink goes hard after the solvent has been released.
Awesome as always 💥
One of the ingredients is a sealant, and reacts with water to cure. This is to keep ink from bleeding or blurring in humid or wet conditions. I imagine this is what makes the ink solid on the water surface.
During my tenure as a teenage delinquent street artist we used to make some really nasty ink by getting a box of biros, stripping the ink tubes out of them and then leaving them in brake fluid to dissolve. We'd then make what was called a mop out of an empty roll-on deodorant tube which you'd popped the ball out of and replaced with a dish sponge after filling the tube with the ink. The stuff could etch itself so deeply into concrete that you'd have to chip it off to remove the tags, if you painted over it it would just keep bleeding through endlessly. If you got it on your skin it'd take months to get rid of the stain and it'd never come out of clothes
5:02 that's a great demonstration of a star
My old journals, written in Bic ballpoint, have a greesy looking halo around the ink trace. The paper is yellowed and translucent for a few millimeters in every direction. I like fountain pens too and sometimes used those and they do not seem to have the ink spreading through the paper problem.
The ink trail left on the surface reminds me of the film that you get on a mug of black tea if you leave your tea in the mug way too long.
Dyes and pigments are different in a way that dyes dissolve in water / solvent, while pigment remains in it "crushed" particulate state. Maybe the combination of lubricant and powdered pigment is what causes the hard film residue on the surface.
Commercial inks contain a shellacing agent to protect the pigment particles. The pigment isn’t dissolved in ink, but dispersed. That’s one of the main differences between a pigment and a dye, as the dye is dissolved in the fluid medium. The dye physically bonds to the paper fibers, pigments don’t. I believe the sheeting you’re seeing is the shellacing agent.
Always love everything about your videos! Your smile, your energy! The delivery. Relieves me of bad vibes.
The behavior of the phenoxy ethanol at 4:15 looks to be a much slower version of the dissolution at 3:53. Maybe this is because it was "corraled" by the other things on the surface. Either process looks like the chemical dissolution is maximizing it's perimeter to surface area or volume. Hence the fractal spikiness.
Regarding pure vs dilute oleic acid forming a blob vs a thin film, I think the surface tension of the pure oleic acid keeps it together whereas the dilute oleic acid solution has a surface tension vanishingly close to pure water. Once the dilute oleic acid is spread out, the "friction" to re-agglomerate is too high.
4:20 thats some serious prometheus stuff right there. ridley scott taking notes.
The crusty nature of the pen looks important.
The way it is holding together, reminds me of a focused exhaust.
This factor reduces the amount of surface spreading wasted on expanding to both sides.
Seems to me that the propulsion is being driven by the phenoxyethanol, and the reason that that the ink is forming rafts rather than just dispersing in the water is because it's mixed with the oleic acid which appears to be hydrophobic.
Cool video, and a cool demonstration to do with kids. Might be worth hitting up a pen ink manufacturer. They might be will to work with you for some publicity.
4:20, wow looks almost like a fractal! Reminds me of Barnsley's fern.
Once again, an awesome thing I had no idea I wanted to know about. Thanks, Steve!
Might also be the order of blending. The dye molecules are coated with the oleic acid, making them insoluble in general, then coated with the solvent, to form small ink granules, that then will float on the top, bonded together by being non polar molecules in a thin sheet, and floating on the ionic liquid. Thus the need for a surfactant that allows the tiny ink granules to be broken, when shear mixing occurs in the ball tip, so they will be able to adhere to the paper when the solvent finally does evaporate.
4:18 The fractals look like a dragon or monster in some sort of fairy tale. So cool
The physicochemical properties of the dye can change dramatically if you don't have the exact same formulation. E.g. if the particle size is different or the commercial stuff has a surface bonded molecule to help it stay suspended
The most logical answer to me is that there's probably an additive such as grease or wax that makes it form that type of a coating. Since we're dealing with Phenoxyethanol, these cheap and easy to come by ingredients would be soluble and therefor have a different viscosity. Once the Phenoxyethanol evaporates, these additives then change back into their original state. Combined with the cooler temperature of the water, it's easy to understand why the "crusty" coating would form.
5:02 reminds me of the sun... idk why, maybe because of its core shrinking and collapsing on itself