Also, I'm very curious to see a test of dark pots vs light pots although you touched on it with the shiny pot bit. For example, Mors Kochanski used to say a blackened pot will use less fuel vs a shiny pot. I've never tested it.
@@BradyPatterson I tested this with a shiny aluminum vs heat paint and saw a dramatic increase in time to boil. A better test would be anodized vs shiny, as I think the paint was acting as an insulator.
@@GearSkeptic you could try the black grease pot with the coating on it, then rough sand, then polish. I used that as a gold standard for a cheap pot for boy scouts.
ANSWERS TO ALL THE QUESTIONS BACKPACKERS DEBATE ABOUT FOR THOUSANDS OF MILES!!! Been following since close to the beginning! You are directly making all of us MORE EFFICIENT HIKERS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
So after all these fantastic highly educational videos of yours I came to my own little conclusion: If you're a fair weather (3 season temps) weekend warrior( 1-2 nights max) kind of hiker, a brs 3000t stove and a super thin 0.3mm toaks 550 is all you need if you're just boiling water for a dehydrated meal. A cheap combo that won't break the bank, as ultralight weight as it gets (for gas as fuel anyways), just make sure to use low heat and you can safely leave the lid home for 1-2 nights of backpacking. Great, great series sir. Thank you very much.
Did they fix the BRS flaws yet? It's super light but I have seen A LOT of reviews on it bending itself from the heat of the stove melting the pot stand feet. Thats a no go for me. I don't care if I save an ounce of weight if it becomes a paperweight and/or a liability. For me the Soto Windmaster with the triflex pot stand is awesome at 2.3 oz or the Soto Amicus is also good but not regulated and it's actually heavier than the larger wind master at 2.7oz. I have both of them to be honest (because everyone needs multiple stoves LOL) It still does pretty well in the wind but not as well as the wind master.
@@Raevenswood This does not happen, when you just boil your 300-400ml water for a meal. This can happen when you heat/cook larger amounts of water for a longer time.
I’ve been eyeing that Toaks 900 for a long time - seems like the perfect pot for bikepacking especially if you cook actual food rather than just boil - which I do. Great content GearSkeptic thank you very much.
Imagine discovering these videos and binge watching them all at once. This was my circumstance, and it was indeed youtube heaven. Thank you for the empirical approach, candid acknowledgement of experiment parameter issues, and the healthy dosage of chuckle worthy humor. Best video series for gear nerds I have ever watched. It was truly a pleasure!
Watching your videos is like listening to a great reading of an academic paper - it's structured the same, same sort of content, but endlessly fascinating. As a scientist, I absolutely love your videos.
Heating up a 200 g aluminium pot by 80 degrees theoretically requires another 7.4 kJ (0.15 g butane) compared to 161 g titanium. This might explain some of the difference you are seeing. Although it is not that much compared to the 139 kJ (2.8 g butane) needed for the water, it especially makes large aluminium pots with heatsinks inefficent for small amounts of water. Thanks for all the testing!
Fair point! In Part 4 on HX pots, I considered the one-batch penalty that a more massive system suffers (the heavy burner system of the MSR Reactor). So, I tested it with two consecutive boils, where the second boil benefited from the already-heated up burner. Noticeable change.
@@GearSkeptic indeed, nice that your measurements are accurate enough to see these things. The MSR 2.0 l actually requires more than twice the amount of energy to heat up empty compared to the Toaks 1600, eventhoug they weight difference is not that big. With 830 ml of water this is a 2.5% change, close to the 2% you measured.
My plan is to try cold soaking this summer, but I am still here fascinated by this series. I would watch Gear Skeptic test just about anything at this point
I haven’t watched your new video yet, but here’s a thumbs up already-like it-because your previous videos are great! You’re doing a great job. Unfortunately, if I had known all this earlier, it would have saved me a lot of money and time-though maybe it wouldn’t have been as exciting. :) I learned a lot of this through trial and error back when I used to go on hikes old-days often, but it’s still exciting. Well done!
The emissivity hypothesis is really interesting. I learned from a survival instructor to get BBQ paint, and paint the bottom of my pots black for more efficiency, since it absorbed more heat from the (in this case) cook fire. But black is also generally more emissive. I wonder how a shiny-everywhere pot would compare with a shiny-everywhere-but-soot-black-bottom pot? I probably won't try to look it up, but I imagine you could look up "A and E" charts for both shiny stainless and BBQ paint and test that. Now I'm wondering if one can mirror polish anodized titanium. More generally, it amuses me that one could eventually figure out the ideal pot efficiency for any given test scenario - material, level of polish, blackened and/or dimpled bottom, HX attachment/integration, type of stove, wind screen...
Ha! You’re reading my mind. I was just thinking about what I’d need to polish titanium. Also, I do have plans to test black pots (both painted and natural soot). I like your idea of polished sides and a black bottom!
@@GearSkepticThank you! I look forward to those tests. For what it's worth, titanium is generally less hard than steel (though I don't know about the anodized coating), I'd assume you could use a buffing wheel and similar green chromium oxide compound to what they use to strop knives. If not, one should be able to find assortments of diamond compounds and pastes and sprays for stropping (Chef Knives to Go or Gritomatic are a couple of good places to look), and diamond ought to be able to polish nearly anything. I'm also inclined to believe that your heat sink hypothesis is more like "heat sink theory", as you've proven it before. A heat exchanger is just your heat sink hypothesis from this video working in reverse - more metal in the flame conducting heat heats up the bottom of the pot more. From your previous videos, I seem to recall that a heat exchanger on the bottom of the pot in the flame led to an efficiency improvement, whereas one that surrounded the outsides made less difference. Seems to me that a heatsink directly in the flame (such as a jetboil) is conducting more heat into the bottom of the pot, whereas the heatsink that clips around the outside (an MSR one, I think?) might gain a bit by channeling exhaust gases nearer the pot, but also lose some by letting the pot's sides conduct heat into the surrounding environment. (I may have that wrong, but I suppose if anyone can correctly remember the content of the previous video, it'd be you.)
Spectacular as always. Do you have a way to donate? Also, I spotted an interesting video that is right up your alley. Re sleeping pads, I watched a video where someone compared an inflatable air pad to foam pads. He found that even one layer of foam pad with an r value of 1.5 was similar coldness feeling to the r value 5-6 sleeping pad. He theorized it was due to the false testing method used as the inflatable pad allowed cold air in the sides as the insulation was designed ground to top side. You have pretty much done everything on cooking. Sleeping pads have so many opportunities and such a crucial backpacking tool. Especially since foam pads are often used in winter for a second safety layer and your work could help save lives - or at least a cold sleep! I plan to use an r3.4 pad plus foam in winter (-10 deg C max) and wonder if in real world how it will compare to an r5.8 air mat. Keep up the amazing work!!
The larger aluminum pots acting like heat sinks makes sense also when you think about the side walls potentially sucking heat from the water, beyond just pulling it from the interface with the flame front. Also the aluminum ones generally seem to have a darker surface which will mean the radiation could be higher. Also while the delta T is important, the conductivity/convection coefficient is still a key part of the heat equation. Thank you for all of your work!
Another comment also made an interesting point. Hotspots will provoke more convection in the water itself, which can be a significant contributor to effective transfer.
One way to test this would be the addition of a coozie. Limit/reduce the shedding of heat to atmosphere. Would be interesting to see how much (little) benefit there is to a coozie, on various materials. I suspect that titanium and polished stainless won't benefit terribly much, while aluminum will.
I think the other half of the titanium working well is that some heat is also leaving the system through the sides of the pot. The higher the conductivity, the warmer the sides get, and that's more surface area transferring heat into the environment... And further, heat from the water will be heating the sides of the pot, and the lower-conductivity material will make that happen just a little slower. Lower conductivity = more insulation. I wonder if this could be tested by re-running in a colder environment to emphasize the effect. That explanation also works for the silicone-sided kettle, only even moreso as silicone is even worse at conducting heat. That's actually a rather ingenious design and maybe I'll get one for my next trek.
Interesting ideas. Another comment pointed out that hotspots may promote more convection within the water itself, which could contribute to transfer. I’d like to test the importance of sides with cozies. Colder weather, as you say, and wind is already suspected as a factor vs pot surface area from Part 2.
@@GearSkeptic That would be interesting since I've been eyeing up the new Petrel G2 HE pot which is available either with a (neoprene ?) cozie or without and whether the cozie can justify its own weight.
@@GearSkeptic Yes, please, on the coozie testing. I suspect aluminum with a coozie to be the most efficient combo per $, and very nearly the most efficient per gram.
Hi, little bit off topic but after watching this video it got me thinking…..if you adjusted the flame level after a certain period of time (for example start at high flame level and reduced to medium flame level after a minute) would there be savings in fuel consumption and how would boil times be affected? Thanks.
Heat Sink. A way to evaluate this is to use a contact thermal probe and measure the temperature of the above the water line. If it is way above 212 then the heat is transferring up the sidewalls and less into the water. If it is less that 212, then you are probably transferring more heat to the water. Make sense?
Hmm. Not sure. My guess is that transfer into the water is, by far, the more significant. After all, you can actually boil water in a plastic bag. Such is the water’s ability to pull heat off the container surface.
Fantastic science. For the double batch, i wonder if the increased water column height actually helps insulate the water deeper in the pot against the flame to help heat retention until the convection helps to stir the water and transfer the heat to the larger volume of water. Completely speculative. The silicone on the collapsible kettle insulating the heat is an interesting concept too.
Another comment pointed out that convection within the water itself can contribute to transfer. I’m wondering if a taller column gives more play to that.
Good video. From the heat transfer work that I have done, I would agree that the heatsink hypothesis is correct. I believe the earlier temperature differential theory is a red herring. The difference between pot sizes is a function of surface area. As the surface area increases, the heat flux from the sides of the aluminum pots subtracts from the heat flux in from the burner. You can think of the other pot walls as insulators (in comparison to aluminum). Conclusion, keep your pot small if using aluminum.
Thanks for another interesting video. Only thing I noticed is that the medium size Alu pot was significantly taller than the others. Personally, I used a Trangia Duossal pot before switching to titanium. Mostly to avoid using aluminum pots for 5-6 months thruhikes (even if using aluminum supposedly is a non-issue) and Duossal pots have a stainless steel inner and aluminum outside for better heat transfer. I don't think Duossal pots would do well in the context of this video tough. They are not that heavy, but don't' come with a lid and need a separate handle that also add weight. I've seen silicone pots and bottles getting more and more popular. Don't see much point with pots as I prefer a hard container to keep stove and gas container anyway, but collapsible bottles for extra capacity can be extremely useful. What I'm not sure about is how safe silicone rubber is for use with hot/boiling water.
As a possible follow up episodes? From the old Zen Stove website (from memory?), there’s theory that the old billy can ‘cooks / heats faster’. It heats up faster because of the layer of black soot that covers the bottom of the pot. The suspicious is that the black colour helps to absorb the radiate heat of the ‘fire’, opposed to a new ‘shinny’ pot that reflects the heat. I would like to know your thoughts on that theory?
It's also possible that this effect (faster boil with black pots) happens mostly over a campfire rather than a camp stove. Because there's lots of radiative heat from a campfire but for a stove it might not matter as much. Dunno, just a thought.
I'd like to know the answer also. I believe people think this because the sun heats up dark clothes,etc, sooner than lighter colors. But would a flame from a stove or fire be attracted to darker items?
@@GearSkeptic back to the boiling cave with you. Seriously though I've only done two boiling tests and a lot less rigorously than you but i can somewhat commiserate, sorry.
if for some ungodly reason you wanted to add more pots to your repertoire Imusa has a couple of aluminum options for under $6 and they are allegedly very lightweight. There is a .7qt (4" diameter and ~70grams) and 1.25qt (5 inch diameter ~100g) no lids though afaik.
What’s interesting is that these pot efficiency stats only hold up for the stove type you’re testing with - canister stoves in this case. If you moved to an alcohol stove, you’d find stainless steel could take 2x the fuel that titanium needs, if not more.
What a nerd you have to be to do all this - I LOVE IT! But one question remains: how much GAS did you use to do all these tests? And what did you do with all that hot water? Freeze it? I mean, you may need hot water anytime :D
Amazing! To give more confidence in the Results, I’d be curious to See the difference in Performance for two post that have the Same Size and Material, but differ in thickness.
the outside of the pot (including most of the bottom) will be very close to the water temperature, you're not getting significant conduction from the bottom up the sides however the higher conductivity pots will be a more effective heat sink for cooling the water inside the pot, so the heatsink theory could hold up there. My intuition says the fitment of the lids could make a significant difference too.
Very interesting to see. I'm curious as to see how much convective and radiative heat loss matters off the sides. Might be something worth opening excel to calculate hah!
This series is just too interesting. Makes me see the gear i own in a different light. In curious thought. 21:45 i noticed the patina on the Tokes 550. Could there be efficiency issues from limestone or oxide deposits insulating the hotspots? The Emissivity of old steel had a chart but i figured that's more for the outside.
Yah, I think emissivity plays for the outside. I suppose a coating of scale could act as insulation, if it was thick enough. The stuff on my 550 is very thin. You couldn’t feel it with a finger nail.
@GearSkeptic interesting. I tend to descale my glass electric kettle twice a year. There's not much limestone in the water here. I do notice changes in air bubbles clinging to the bottom though. I could see hot spots losing potency over time. Carrying a pouch of hot lemon as Impromptu descaler might be an option.
Love it. While your tests are consistent, I wonder how they would change if you changed elevation, or the pots had been used long enough to form coatings from burn marks and oxidation. Would the results change consistently across the samples, or would a different material become "king".
Something I thought of, while the bottom of the pot heats up, the pot is transferring thermal energy to the water, but at the same time the water is transferring it's thermal energy to the top and sides of the pot, more thermal mass and better conductivity would mean it is more efficient are sucking heat out of the water to balance the temp on the side walls of the pot with the water temp. It would be interesting to see the temperature of the sidewalls, at the top, of each pot to see how much energy is lost to warming the pot.
Indeed. And, then there is convection of the water itself, carrying that heat all around to warm the upper sides faster than just conduction from flame through the metal would.
Since you have all of these pots, which ones are wide enough to fit a standard fuel canister inside of it that's between 500-700mL. The one I currently have fits so tight it can get stuck some times and I'm looking for one that has a lid. Thanks for the engineering take on hiking.
Any of them will nest a 110g can, and the medium and large pots will take a 227g (in width, some like the Toaks 700 and 900 are shorter than a medium can).
There is also a pot with titanium bottom and carbon sides (the joule thief). Going with your Hippthesis, it would performe nicely. Problem here would be no direct comparison, as it is a HX pot
So what I'm hearing is a pot made out of alluminum with a casing of 304 steel on the outside should allow the alluminum to heat the water quickly without loosing as much heat to conduction through the steel and then radiated into the environment.
All of this leads to the reason high-end cooking pots have layers of copper or aluminum clad bases and stainless steel sides... the clad base to get the heat distributed to where you want it, but not on the sides where it would just aid the heat escaping.
I’d say so. Also, pans are different than pots. An actual frying pan in aluminum, even a backpacking brand, will be significantly thicker than an aluminum pot for just boiling (and consequently heavier).
Heat transfer isn't just related to the conductivity and the surface area, but also to the thickness of the material: To realize why this is obviously the case it may be helpful to imagine the materials as insulators between the flame and the water instead (if the point wasn't already completely obvious.) Alas, the one aluminum cup that won was also the thickest, and in any case the thickness difference isn't enough to change the conductiveness ranking between the pots. Can't be that, then. I don't particularly resonate with the hotspot => better heat transfer idea, because while it may mean a localized higher delta-T from the perspective of the water, it also means a higher outside temperature, which should mean a lower delta-T from the perspective of the gasses. The gas-pot interface is likely the less efficient of the two, otherwise a system heating the pot directly (induction) wouldn't have much advantage over a gas stove wrt to room heating in home cooking situations. That room heating can only come from the heat that didn't enter the food through the pot. EDIT: this middle section is also a good place to note that in the heat sink perspective, the entire pot with the fluid in it is acting like a heat sink. It's sinking away the heat from the combustion gases and that leads to the pot and the water heating up. Also explains HX pot efficiency. What about the shapes of the bottoms (that you also mention at the end)? Might cause more or less perturbation of the hot gasses, affecting the heat transfer rate at the gas-pot interface? Of the smallest three pots, the aluminum one has the most pronounced shape to it and was the winner. This appears to repeat in the middle category, with the bottom with the most pronounced shape/edge winning. The large pot category seems like it may also follow this rule, but the differences in shape seem even smaller there. Might suggest a hammered surface like in old-timey copper pots might provide a middle ground between completely flat and a heat exchanger system. But, if such macro scale shapes matter, what's to say surface finish doesn't also play a role?
I'm not totally convinced on the heat sink hypothesis. My intuition says that the interface between metal and water is so efficient that there is no way for the metal to heat up enough to cause a noticeable difference in the rate of heat transfer. But say they metal of the pot was getting hotter, wouldn't that also decrease the rate of heat transfer from the combustion gasses to pot? What isn't speculation though it that the three materials tested have different specific heat capacities. I wouldn't have thought that it would be enough to make a difference but your results were close enough to make me question it. Pure aluminum is 0.897 J/g/K, titanium is 0.523, and iron is 0.449. A 120 gram titanium pot with 415 grams of water, going from 15 C to 95 C, would require 143,849 J. A 160 gram aluminum pot with 415 grams of water, going from 15 C to 95 C, would require 150,310J. That's a 4.5% increase. Of course that's for pure metals not the alloys that are actually used, and there might be other materials present like plastic lids. But I think it demonstrates the point.
Interesting idea. I don’t think they are mutually exclusive, though.
2 วันที่ผ่านมา
Titanium pots are great as long as you're only boiling water. Otherwise, you'll get burned spots very soon and it's a pain in the arse to scrub on trail.
As far as materials go, the The Engineering Toolbox website has a table of thermal conductivity for metals and common metal alloys. The thermal coefficient is measured as “k values”. In general, the higher the k value, the better the thermal conductivity. Stainless steel is slightly more conductive than titanium, and both are far more conductive than aluminum in the temperature ranges discussed in the video. Bear in mind that these values are affected by material area and thickness, and the temperature difference between the two sides of the material. The table has a link to a calculator that takes these into account. As far as the small aluminum pot, you measured the thickness of the sides, not the bottoms.
You’ve got that backwards. Try the calculator you mentioned. It will show you that a higher k number results in increased heat transfer. Aluminum is a far better conductor. As far as the bottom thickness, you need to consider how these are manufactured. They aren’t cast. They are stamped from sheet stock. Expect all sides to be similar.
@gearskeptic Sorry, typo. I have edited it. When stamping, the material stretches. The bottom may not be the same thickness. Also, the dies may be gapped to allow greater wall thickness. You would have to measure to be sure, but it was just a hypothesis. Your heat sink theory could be the answer, or even the strengthening ring molded into the bottom (more surface area and/or heat trapped inside the ring lip). It is difficult to quantify, but I think you made your point with the spilled water demo. There comes a point where reducing weight can become absurd. I often get criticized on trail for not sawing off the handle of my toothbrush. Since I am not an Army Ranger trying to carry more ammo, I am not going to obsess about it. As long as I can comfortably carry it I am good. I do find your fuel savings videos very handy, and recently found that the use of low flame works for liquid fuel also. Since I live in California, I can no longer purchase butane canisters. My current setup is a Trangia with a kerosene burner adapter. I ditch everything but the kettle, windshield, and base. Been criticized for that too. Same answer. Saving fuel makes sense though, since it is the densest single item I carry other than water, and requires a relatively heavy bottle to carry it in. Now if they could just do something about the hated but required bear canisters…
First of all: thank you for the good job!!! The heatsink hypothetis sounds logical to me. I wonder what the impact of a Neopren sleeve would be then. Since I am into alcohol stoves, I allways watch your videos and think, what the parallels would be in the „alcohol-stove -universe“. I would be very curious how a Trail Designs sidewinder with the 700ml titanium pot and the kohin burner would perform. It has a (very😂) low flame, large pot diameter, reduced wind impact and the Heat sink effect through the sides ….. 🥸 Thanks again. It’s all ways fun to watch your videos.
Hypothesis: Dimple matters. Imagine the heat (hot gas and air) rising. As that hot gas rises, it's trapped by the dimple. It's the same as water being trapped in the dimple when the pot is upside down. The dimple forms a potential-well, trapping the hottest gas from spilling (upward) and into the atmosphere. This was discussed several videos ago when this author mentioned making a windscreen/skirt that dropped a few mm below the pan's bottom. Dimple forms the same potential-well to hold hot-gas against the pot-bottom that extra half-second to improve efficiency. It was worth exploring then, as now. Bigger-dimple (or windscreen) = better-efficiency, to a point. But to what point? What is the optimal (dimple) cavity depth? For boiling water a dimple is surely the lowest weight heat-entrapment geometry, but maybe not the best for frying or for cleanup? Also, a skirt (as previously discussed) is much simpler to test. A single skirt can be utilized to test many potential-well depths. One might further speculate the optimal dimple-depth (or windscreen-skirt-depth) occurs right about when stove fuel burn begins to be impacted by too much skirt-depth. For all the nonsensical fin-geometries manufacturer's have produced, a skirt or dimple would appear to be more effective at lighter weight and less cost. A three-way win.
In case you don't hear it enough, you're the hero we didn't know we needed
Also, I'm very curious to see a test of dark pots vs light pots although you touched on it with the shiny pot bit. For example, Mors Kochanski used to say a blackened pot will use less fuel vs a shiny pot. I've never tested it.
@@BradyPatterson it’s on my list! Need to try painted-black vs genuine soot. Maybe some other coatings with relevant properties.
@@GearSkeptic Japanned, black anodized.
@@BradyPatterson I tested this with a shiny aluminum vs heat paint and saw a dramatic increase in time to boil. A better test would be anodized vs shiny, as I think the paint was acting as an insulator.
@@GearSkeptic you could try the black grease pot with the coating on it, then rough sand, then polish. I used that as a gold standard for a cheap pot for boy scouts.
Huh. I didn't expect you to come across my feed to at least another 5 months!
@@joshuacheung6518 if life actually leaves me alone, I can get stuff done!
Most eloquent pair of hands on TH-cam
ANSWERS TO ALL THE QUESTIONS BACKPACKERS DEBATE ABOUT FOR THOUSANDS OF MILES!!! Been following since close to the beginning! You are directly making all of us MORE EFFICIENT HIKERS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Gotta have something to talk about around the campfire!
A very inefficient use of exclamation points, but I totally agree with you! GS is the best.
A teacher who can make math and physics interesting AND entertaining while maintaining skepticism. Thank you.
So after all these fantastic highly educational videos of yours I came to my own little conclusion: If you're a fair weather (3 season temps) weekend warrior( 1-2 nights max) kind of hiker, a brs 3000t stove and a super thin 0.3mm toaks 550 is all you need if you're just boiling water for a dehydrated meal. A cheap combo that won't break the bank, as ultralight weight as it gets (for gas as fuel anyways), just make sure to use low heat and you can safely leave the lid home for 1-2 nights of backpacking. Great, great series sir. Thank you very much.
It’s a great combo. Soto Amicus is also a great stove for any kind of wind.
Did they fix the BRS flaws yet? It's super light but I have seen A LOT of reviews on it bending itself from the heat of the stove melting the pot stand feet. Thats a no go for me. I don't care if I save an ounce of weight if it becomes a paperweight and/or a liability. For me the Soto Windmaster with the triflex pot stand is awesome at 2.3 oz or the Soto Amicus is also good but not regulated and it's actually heavier than the larger wind master at 2.7oz. I have both of them to be honest (because everyone needs multiple stoves LOL) It still does pretty well in the wind but not as well as the wind master.
@@Raevenswood This does not happen, when you just boil your 300-400ml water for a meal.
This can happen when you heat/cook larger amounts of water for a longer time.
@ well that’s good to know but also my other gripe about it is it’s not very efficient in wind. For only $20 I might try it though 🤷♂️🙂
I’ve been eyeing that Toaks 900 for a long time - seems like the perfect pot for bikepacking especially if you cook actual food rather than just boil - which I do. Great content GearSkeptic thank you very much.
Imagine discovering these videos and binge watching them all at once. This was my circumstance, and it was indeed youtube heaven. Thank you for the empirical approach, candid acknowledgement of experiment parameter issues, and the healthy dosage of chuckle worthy humor. Best video series for gear nerds I have ever watched. It was truly a pleasure!
Very kind of you, and much appreciated! I hope some of it is useful.
I loved this explanation by the two naked sock puppets. Did anyone else see their own personal failure in the Rorschach test near the end?
🤣
Watching your videos is like listening to a great reading of an academic paper - it's structured the same, same sort of content, but endlessly fascinating. As a scientist, I absolutely love your videos.
Very high praise! I am not worthy, but thank you!
As informative as your channel is, you also give me the extra bonus of making me chuckle, I love your content. Good one on the Count R. Vailing!
🥸
The smaller, but hotter, hot spots on the Ti pots may promote convection within the fluid. Convection is very efficient for heat transfer.
Ah, I like it! Sort of a secondary, synergistic effect.
2 videos in less than a month! I'm skeptical that he'll keep up this pace. Get it? heh
Your skepticism is well placed!
Absolutely excellent video and only us camping nerds would sit and watch the entire video and really enjoy it!
@@MichiganHiker 🤓
Great tests as always. Interesting results. They make sense as you explain them. Thanks for sharing
Much appreciated, sir!
Heating up a 200 g aluminium pot by 80 degrees theoretically requires another 7.4 kJ (0.15 g butane) compared to 161 g titanium. This might explain some of the difference you are seeing. Although it is not that much compared to the 139 kJ (2.8 g butane) needed for the water, it especially makes large aluminium pots with heatsinks inefficent for small amounts of water.
Thanks for all the testing!
Fair point! In Part 4 on HX pots, I considered the one-batch penalty that a more massive system suffers (the heavy burner system of the MSR Reactor). So, I tested it with two consecutive boils, where the second boil benefited from the already-heated up burner. Noticeable change.
@@GearSkeptic indeed, nice that your measurements are accurate enough to see these things. The MSR 2.0 l actually requires more than twice the amount of energy to heat up empty compared to the Toaks 1600, eventhoug they weight difference is not that big. With 830 ml of water this is a 2.5% change, close to the 2% you measured.
i missed the test with the heatsink where can i find that
On vacation, so I haven't watched, but I know it's good.
Thank you for all you do.
My plan is to try cold soaking this summer, but I am still here fascinated by this series. I would watch Gear Skeptic test just about anything at this point
I love your simple and stupidly though review
I haven’t watched your new video yet, but here’s a thumbs up already-like it-because your previous videos are great! You’re doing a great job.
Unfortunately, if I had known all this earlier, it would have saved me a lot of money and time-though maybe it wouldn’t have been as exciting. :) I learned a lot of this through trial and error back when I used to go on hikes old-days often, but it’s still exciting. Well done!
The emissivity hypothesis is really interesting. I learned from a survival instructor to get BBQ paint, and paint the bottom of my pots black for more efficiency, since it absorbed more heat from the (in this case) cook fire. But black is also generally more emissive. I wonder how a shiny-everywhere pot would compare with a shiny-everywhere-but-soot-black-bottom pot? I probably won't try to look it up, but I imagine you could look up "A and E" charts for both shiny stainless and BBQ paint and test that.
Now I'm wondering if one can mirror polish anodized titanium. More generally, it amuses me that one could eventually figure out the ideal pot efficiency for any given test scenario - material, level of polish, blackened and/or dimpled bottom, HX attachment/integration, type of stove, wind screen...
Ha! You’re reading my mind. I was just thinking about what I’d need to polish titanium.
Also, I do have plans to test black pots (both painted and natural soot). I like your idea of polished sides and a black bottom!
@@GearSkepticThank you! I look forward to those tests.
For what it's worth, titanium is generally less hard than steel (though I don't know about the anodized coating), I'd assume you could use a buffing wheel and similar green chromium oxide compound to what they use to strop knives. If not, one should be able to find assortments of diamond compounds and pastes and sprays for stropping (Chef Knives to Go or Gritomatic are a couple of good places to look), and diamond ought to be able to polish nearly anything.
I'm also inclined to believe that your heat sink hypothesis is more like "heat sink theory", as you've proven it before. A heat exchanger is just your heat sink hypothesis from this video working in reverse - more metal in the flame conducting heat heats up the bottom of the pot more. From your previous videos, I seem to recall that a heat exchanger on the bottom of the pot in the flame led to an efficiency improvement, whereas one that surrounded the outsides made less difference. Seems to me that a heatsink directly in the flame (such as a jetboil) is conducting more heat into the bottom of the pot, whereas the heatsink that clips around the outside (an MSR one, I think?) might gain a bit by channeling exhaust gases nearer the pot, but also lose some by letting the pot's sides conduct heat into the surrounding environment. (I may have that wrong, but I suppose if anyone can correctly remember the content of the previous video, it'd be you.)
Spectacular as always. Do you have a way to donate? Also, I spotted an interesting video that is right up your alley. Re sleeping pads, I watched a video where someone compared an inflatable air pad to foam pads. He found that even one layer of foam pad with an r value of 1.5 was similar coldness feeling to the r value 5-6 sleeping pad. He theorized it was due to the false testing method used as the inflatable pad allowed cold air in the sides as the insulation was designed ground to top side. You have pretty much done everything on cooking. Sleeping pads have so many opportunities and such a crucial backpacking tool. Especially since foam pads are often used in winter for a second safety layer and your work could help save lives - or at least a cold sleep! I plan to use an r3.4 pad plus foam in winter (-10 deg C max) and wonder if in real world how it will compare to an r5.8 air mat. Keep up the amazing work!!
Thanks, but no need to donate. I did a video about blowing up pads with your breath, and that also has me thinking about ways to test pads better.
you're back, yaayy! Personally not a stove user, but good to see you're active again!
The larger aluminum pots acting like heat sinks makes sense also when you think about the side walls potentially sucking heat from the water, beyond just pulling it from the interface with the flame front. Also the aluminum ones generally seem to have a darker surface which will mean the radiation could be higher.
Also while the delta T is important, the conductivity/convection coefficient is still a key part of the heat equation.
Thank you for all of your work!
Another comment also made an interesting point. Hotspots will provoke more convection in the water itself, which can be a significant contributor to effective transfer.
@GearSkeptic that is a good point! Time to dig through more comments!
One way to test this would be the addition of a coozie. Limit/reduce the shedding of heat to atmosphere. Would be interesting to see how much (little) benefit there is to a coozie, on various materials. I suspect that titanium and polished stainless won't benefit terribly much, while aluminum will.
I think the other half of the titanium working well is that some heat is also leaving the system through the sides of the pot. The higher the conductivity, the warmer the sides get, and that's more surface area transferring heat into the environment... And further, heat from the water will be heating the sides of the pot, and the lower-conductivity material will make that happen just a little slower. Lower conductivity = more insulation. I wonder if this could be tested by re-running in a colder environment to emphasize the effect.
That explanation also works for the silicone-sided kettle, only even moreso as silicone is even worse at conducting heat. That's actually a rather ingenious design and maybe I'll get one for my next trek.
Interesting ideas. Another comment pointed out that hotspots may promote more convection within the water itself, which could contribute to transfer.
I’d like to test the importance of sides with cozies. Colder weather, as you say, and wind is already suspected as a factor vs pot surface area from Part 2.
@@GearSkeptic That would be interesting since I've been eyeing up the new Petrel G2 HE pot which is available either with a (neoprene ?) cozie or without and whether the cozie can justify its own weight.
@@GearSkeptic Yes, please, on the coozie testing. I suspect aluminum with a coozie to be the most efficient combo per $, and very nearly the most efficient per gram.
That's a load off my mind. Cheers
Thank you for this info!!
Most welcome!
Great, now the UL beta is going to be polishing your pot for reduced emissivity
So hard to keep up with the trends! 😉
Hi, little bit off topic but after watching this video it got me thinking…..if you adjusted the flame level after a certain period of time (for example start at high flame level and reduced to medium flame level after a minute) would there be savings in fuel consumption and how would boil times be affected? Thanks.
another awesome contribution !
It might be worth to look into heat capacity of the pot itself, since the pot itself needs to be heated to.
As always, a verry enjoyable video.
Good point. Heat capacity and conductivity might play a synergistic role.
Heat Sink. A way to evaluate this is to use a contact thermal probe and measure the temperature of the above the water line. If it is way above 212 then the heat is transferring up the sidewalls and less into the water. If it is less that 212, then you are probably transferring more heat to the water. Make sense?
Hmm. Not sure. My guess is that transfer into the water is, by far, the more significant. After all, you can actually boil water in a plastic bag. Such is the water’s ability to pull heat off the container surface.
Fantastic science. For the double batch, i wonder if the increased water column height actually helps insulate the water deeper in the pot against the flame to help heat retention until the convection helps to stir the water and transfer the heat to the larger volume of water. Completely speculative. The silicone on the collapsible kettle insulating the heat is an interesting concept too.
Another comment pointed out that convection within the water itself can contribute to transfer. I’m wondering if a taller column gives more play to that.
@@GearSkeptic At a minimum it gives a lower surface area to volume ratio, and surface area is a factor in insulation/emission.
Pathfinder cantten saved me few times, had no filter working, so I had to boil all my water. I had to do it for 3 days in a row.
It’s nice stuff. Always want something that can handle a wood fire.
Good video. From the heat transfer work that I have done, I would agree that the heatsink hypothesis is correct. I believe the earlier temperature differential theory is a red herring. The difference between pot sizes is a function of surface area. As the surface area increases, the heat flux from the sides of the aluminum pots subtracts from the heat flux in from the burner. You can think of the other pot walls as insulators (in comparison to aluminum). Conclusion, keep your pot small if using aluminum.
Pleasantly surprised to see the X-pot.
I was pleasantly surprised to see its performance! Thinking about getting the newer, 1.1L version.
@GearSkeptic a wide bottom and a small packed size make it efficient in two categories!
Very well done. I would still choose aluminium over titanium though because it's better for cooking regular food.
I have plans to test heat diffusers. My goal is to find a way to soften the hotspots from titanium and still be lighter than aluminum!
@@GearSkeptic I keep thinking about getting some 3d printed titanium pots with built in heat exchanger fins....
👍👍👍 .. very interesting and most informative .. thank you 😊.
Thanks for another interesting video. Only thing I noticed is that the medium size Alu pot was significantly taller than the others.
Personally, I used a Trangia Duossal pot before switching to titanium. Mostly to avoid using aluminum pots for 5-6 months thruhikes (even if using aluminum supposedly is a non-issue) and Duossal pots have a stainless steel inner and aluminum outside for better heat transfer. I don't think Duossal pots would do well in the context of this video tough. They are not that heavy, but don't' come with a lid and need a separate handle that also add weight.
I've seen silicone pots and bottles getting more and more popular. Don't see much point with pots as I prefer a hard container to keep stove and gas container anyway, but collapsible bottles for extra capacity can be extremely useful. What I'm not sure about is how safe silicone rubber is for use with hot/boiling water.
As a possible follow up episodes?
From the old Zen Stove website (from memory?), there’s theory that the old billy can ‘cooks / heats faster’. It heats up faster because of the layer of black soot that covers the bottom of the pot. The suspicious is that the black colour helps to absorb the radiate heat of the ‘fire’, opposed to a new ‘shinny’ pot that reflects the heat.
I would like to know your thoughts on that theory?
I've boiled a lot of water directly over fire, and I'm convinced the black soot helps.
It's also possible that this effect (faster boil with black pots) happens mostly over a campfire rather than a camp stove.
Because there's lots of radiative heat from a campfire but for a stove it might not matter as much. Dunno, just a thought.
I'd like to know the answer also. I believe people think this because the sun heats up dark clothes,etc, sooner than lighter colors. But would a flame from a stove or fire be attracted to darker items?
Yah, blackened pots is a topic on my list!
Great as always. Would be interesting to see if adding a bit of wind would harm the aluminum more the others, particularly the xpot.
Sigh. Means more boils, but I have to agree.
@@GearSkeptic back to the boiling cave with you. Seriously though I've only done two boiling tests and a lot less rigorously than you but i can somewhat commiserate, sorry.
if for some ungodly reason you wanted to add more pots to your repertoire Imusa has a couple of aluminum options for under $6 and they are allegedly very lightweight. There is a .7qt (4" diameter and ~70grams) and 1.25qt (5 inch diameter ~100g) no lids though afaik.
@@ryan92084 duly noted!
What’s interesting is that these pot efficiency stats only hold up for the stove type you’re testing with - canister stoves in this case.
If you moved to an alcohol stove, you’d find stainless steel could take 2x the fuel that titanium needs, if not more.
What a nerd you have to be to do all this - I LOVE IT!
But one question remains: how much GAS did you use to do all these tests? And what did you do with all that hot water? Freeze it? I mean, you may need hot water anytime :D
A nice, long hot bath with plenty of gas bubbles 🤓
Amazing!
To give more confidence in the Results, I’d be curious to See the difference in Performance for two post that have the Same Size and Material, but differ in thickness.
That could be nice. Not aware of any such pot combination, but I can look.
Woot! Part 6!
the outside of the pot (including most of the bottom) will be very close to the water temperature, you're not getting significant conduction from the bottom up the sides
however the higher conductivity pots will be a more effective heat sink for cooling the water inside the pot, so the heatsink theory could hold up there.
My intuition says the fitment of the lids could make a significant difference too.
imusa mug wins for cost, so i am curious how it does with efficiency.
Very interesting to see. I'm curious as to see how much convective and radiative heat loss matters off the sides. Might be something worth opening excel to calculate hah!
On my list would be a test of pot cozies, on and off the same pots to see what the difference might be.
Many thanks! I am wondering if the material thickness was consistent. Could maybe explain difference between small Al and larger Al pots?
You’re my hero.
This series is just too interesting.
Makes me see the gear i own in a different light.
In curious thought.
21:45 i noticed the patina on the Tokes 550.
Could there be efficiency issues from limestone or oxide deposits insulating the hotspots?
The Emissivity of old steel had a chart but i figured that's more for the outside.
Yah, I think emissivity plays for the outside. I suppose a coating of scale could act as insulation, if it was thick enough. The stuff on my 550 is very thin. You couldn’t feel it with a finger nail.
@GearSkeptic interesting.
I tend to descale my glass electric kettle twice a year. There's not much limestone in the water here.
I do notice changes in air bubbles clinging to the bottom though.
I could see hot spots losing potency over time.
Carrying a pouch of hot lemon as Impromptu descaler might be an option.
Love it. While your tests are consistent, I wonder how they would change if you changed elevation, or the pots had been used long enough to form coatings from burn marks and oxidation. Would the results change consistently across the samples, or would a different material become "king".
Something I thought of, while the bottom of the pot heats up, the pot is transferring thermal energy to the water, but at the same time the water is transferring it's thermal energy to the top and sides of the pot, more thermal mass and better conductivity would mean it is more efficient are sucking heat out of the water to balance the temp on the side walls of the pot with the water temp. It would be interesting to see the temperature of the sidewalls, at the top, of each pot to see how much energy is lost to warming the pot.
Indeed. And, then there is convection of the water itself, carrying that heat all around to warm the upper sides faster than just conduction from flame through the metal would.
Since you have all of these pots, which ones are wide enough to fit a standard fuel canister inside of it that's between 500-700mL. The one I currently have fits so tight it can get stuck some times and I'm looking for one that has a lid. Thanks for the engineering take on hiking.
Any of them will nest a 110g can, and the medium and large pots will take a 227g (in width, some like the Toaks 700 and 900 are shorter than a medium can).
You're just the type of guy that need a thermal camera. You'd be able to see what's happening in real time.
Sigh. Expensive, but I do want one!
Great testing and science, but came here to applaud the jokes, thank you 😂
@@larspetter1000 🥸
To test the "heat sink Hippthesis" perhaps a repeat test for 375ml pots? (Enought water for a meal)
There is also a pot with titanium bottom and carbon sides (the joule thief). Going with your Hippthesis, it would performe nicely. Problem here would be no direct comparison, as it is a HX pot
🤩 New Video 🎉
@@TopazFarmerTravels 😊
I'm a vessel voyeur too!!! 😍
So what I'm hearing is a pot made out of alluminum with a casing of 304 steel on the outside should allow the alluminum to heat the water quickly without loosing as much heat to conduction through the steel and then radiated into the environment.
this gets my 73 year old brain cells wheezing BUT I LOVE IT!! THANKS
All of this leads to the reason high-end cooking pots have layers of copper or aluminum clad bases and stainless steel sides... the clad base to get the heat distributed to where you want it, but not on the sides where it would just aid the heat escaping.
I see a video from GearSkeptic, I click.
‘Well done mate’ 😂
@@shermer75 🤓
Your emissivity theory begs the question: is it more efficient to keep that stainless sparkly clean, or let it acquire a soot-blackened coating?
So alu makes a better pan on low heat to fry an egg?
I’d say so. Also, pans are different than pots. An actual frying pan in aluminum, even a backpacking brand, will be significantly thicker than an aluminum pot for just boiling (and consequently heavier).
the comment section here is full of potheads
I give this 2 thumbs up
Cinsa?
Heat transfer isn't just related to the conductivity and the surface area, but also to the thickness of the material: To realize why this is obviously the case it may be helpful to imagine the materials as insulators between the flame and the water instead (if the point wasn't already completely obvious.) Alas, the one aluminum cup that won was also the thickest, and in any case the thickness difference isn't enough to change the conductiveness ranking between the pots. Can't be that, then.
I don't particularly resonate with the hotspot => better heat transfer idea, because while it may mean a localized higher delta-T from the perspective of the water, it also means a higher outside temperature, which should mean a lower delta-T from the perspective of the gasses. The gas-pot interface is likely the less efficient of the two, otherwise a system heating the pot directly (induction) wouldn't have much advantage over a gas stove wrt to room heating in home cooking situations. That room heating can only come from the heat that didn't enter the food through the pot.
EDIT: this middle section is also a good place to note that in the heat sink perspective, the entire pot with the fluid in it is acting like a heat sink. It's sinking away the heat from the combustion gases and that leads to the pot and the water heating up. Also explains HX pot efficiency.
What about the shapes of the bottoms (that you also mention at the end)? Might cause more or less perturbation of the hot gasses, affecting the heat transfer rate at the gas-pot interface? Of the smallest three pots, the aluminum one has the most pronounced shape to it and was the winner. This appears to repeat in the middle category, with the bottom with the most pronounced shape/edge winning. The large pot category seems like it may also follow this rule, but the differences in shape seem even smaller there.
Might suggest a hammered surface like in old-timey copper pots might provide a middle ground between completely flat and a heat exchanger system.
But, if such macro scale shapes matter, what's to say surface finish doesn't also play a role?
I'm not totally convinced on the heat sink hypothesis. My intuition says that the interface between metal and water is so efficient that there is no way for the metal to heat up enough to cause a noticeable difference in the rate of heat transfer.
But say they metal of the pot was getting hotter, wouldn't that also decrease the rate of heat transfer from the combustion gasses to pot?
What isn't speculation though it that the three materials tested have different specific heat capacities. I wouldn't have thought that it would be enough to make a difference but your results were close enough to make me question it.
Pure aluminum is 0.897 J/g/K, titanium is 0.523, and iron is 0.449.
A 120 gram titanium pot with 415 grams of water, going from 15 C to 95 C, would require 143,849 J.
A 160 gram aluminum pot with 415 grams of water, going from 15 C to 95 C, would require 150,310J. That's a 4.5% increase.
Of course that's for pure metals not the alloys that are actually used, and there might be other materials present like plastic lids. But I think it demonstrates the point.
Interesting idea. I don’t think they are mutually exclusive, though.
Titanium pots are great as long as you're only boiling water. Otherwise, you'll get burned spots very soon and it's a pain in the arse to scrub on trail.
Will you make a video after all of your testing to summarizing the best setup and settings to use?
Hmm. I shy away from the word “best”, but I could do some favorite or top-performer type summary.
@@GearSkepticyes please. Scenario based summaries would give us all a happy wiggle.
Seems like most people when boiling water go for high flame level, at least before they see your channel.
I suspect you're right!
So you’re saying I need to get out the buffer and polish the bottoms of my pots huh 🤔
You know the next obvious video is polishing your best titanium pot for reduced emissivity tests
So now we just need a 500mL X-pot kettle...
@@AdmitthatijustdiditX with a heat exchanger bottom!
As far as materials go, the The Engineering Toolbox website has a table of thermal conductivity for metals and common metal alloys. The thermal coefficient is measured as “k values”. In general, the higher the k value, the better the thermal conductivity. Stainless steel is slightly more conductive than titanium, and both are far more conductive than aluminum in the temperature ranges discussed in the video. Bear in mind that these values are affected by material area and thickness, and the temperature difference between the two sides of the material. The table has a link to a calculator that takes these into account.
As far as the small aluminum pot, you measured the thickness of the sides, not the bottoms.
You’ve got that backwards. Try the calculator you mentioned. It will show you that a higher k number results in increased heat transfer. Aluminum is a far better conductor.
As far as the bottom thickness, you need to consider how these are manufactured. They aren’t cast. They are stamped from sheet stock. Expect all sides to be similar.
@gearskeptic
Sorry, typo. I have edited it.
When stamping, the material stretches. The bottom may not be the same thickness. Also, the dies may be gapped to allow greater wall thickness.
You would have to measure to be sure, but it was just a hypothesis.
Your heat sink theory could be the answer, or even the strengthening ring molded into the bottom (more surface area and/or heat trapped inside the ring lip).
It is difficult to quantify, but I think you made your point with the spilled water demo. There comes a point where reducing weight can become absurd.
I often get criticized on trail for not sawing off the handle of my toothbrush. Since I am not an Army Ranger trying to carry more ammo, I am not going to obsess about it. As long as I can comfortably carry it I am good.
I do find your fuel savings videos very handy, and recently found that the use of low flame works for liquid fuel also.
Since I live in California, I can no longer purchase butane canisters.
My current setup is a Trangia with a kerosene burner adapter. I ditch everything but the kettle, windshield, and base. Been criticized for that too. Same answer.
Saving fuel makes sense though, since it is the densest single item I carry other than water, and requires a relatively heavy bottle to carry it in.
Now if they could just do something about the hated but required bear canisters…
This old T.... GearSkeptic 😂
First of all: thank you for the good job!!! The heatsink hypothetis sounds logical to me. I wonder what the impact of a Neopren sleeve would be then.
Since I am into alcohol stoves, I allways watch your videos and think, what the parallels would be in the „alcohol-stove -universe“. I would be very curious how a Trail Designs sidewinder with the 700ml titanium pot and the kohin burner would perform. It has a (very😂) low flame, large pot diameter, reduced wind impact and the Heat sink effect through the sides ….. 🥸
Thanks again.
It’s all ways fun to watch your videos.
I do have cozies on my list to test. That might indicate how much the sides come in play.
Hypothesis: Dimple matters. Imagine the heat (hot gas and air) rising. As that hot gas rises, it's trapped by the dimple. It's the same as water being trapped in the dimple when the pot is upside down. The dimple forms a potential-well, trapping the hottest gas from spilling (upward) and into the atmosphere. This was discussed several videos ago when this author mentioned making a windscreen/skirt that dropped a few mm below the pan's bottom. Dimple forms the same potential-well to hold hot-gas against the pot-bottom that extra half-second to improve efficiency. It was worth exploring then, as now. Bigger-dimple (or windscreen) = better-efficiency, to a point. But to what point? What is the optimal (dimple) cavity depth?
For boiling water a dimple is surely the lowest weight heat-entrapment geometry, but maybe not the best for frying or for cleanup? Also, a skirt (as previously discussed) is much simpler to test. A single skirt can be utilized to test many potential-well depths. One might further speculate the optimal dimple-depth (or windscreen-skirt-depth) occurs right about when stove fuel burn begins to be impacted by too much skirt-depth.
For all the nonsensical fin-geometries manufacturer's have produced, a skirt or dimple would appear to be more effective at lighter weight and less cost. A three-way win.