Excellent! And at the end there you say this wasn’t scientific, but as a PhD student, I’d say this was scientific. You had a blind hypothesis (not knowing what to expect). You had a method (all pieces were painted and cured at the same time, and run through the machine at the same time). You had steps in your method. You had a control piece, and an experiment group. You produced a set of results. You had a conclusion. That sir, is science. Excellent!
Great video. No unnecessary elevator music, barking dogs or air compressor tools making noise. This was a well thought out test and comparison. Well done.
This is literally the best “how to” video on TH-cam! STRAIGHT to the point, extremely clear information Without rambling on for 20 minutes! Now, if you could just post some grwm how to make up videos, that would be great 🤣 lol
FWIW. My understanding is that bare untreated aluminium needs to have an etch primer applied lightly before applying a top coat of epoxy and allowing the epoxy to cure for 7 days. The etch primer has an acid in it that causes the aluminium to have a micro-rough surface which allows the expoxy to grip the surface.
I'm killing myself trying to get paint to stick to some aluminum frame channels. I tried sanding, SE primers, different paints and there is always a spot somewhere peeling off. I'm heading down to Ace tomorrow morning. Thanks.
Excellent video and well done with good presentation on the results. I thought an hour in the deburirng machine would have removed the primer on all of the samples and the test would have been inconclusive - boy, was I wrong. Based on your results, I'm going for the ACE Primer - Thanks again! Unfortunately, I have no value-able input on what causes the dark patina.
My understanding on paint is that any enamel that contains ammonia creates a chemical reaction between the paint and the aluminum substrate that prevents proper adhesion. I've had very good luck with aluminum prepped with a 80-100 grit sandblaster and etching primer.
Thank you for this video. I've done some similar comparisons of primers as part of a motorcycle restoration project, although I didn't use a tumbler. While not a rattle-can, I settled on Eastwood's Epoxy Primer. It's Isocyanate-free, lays down smooth, gets great adhesion, and is incredibly hard. Sanding out a run is a real chore. I use a small Iwata HVLP gun. The same primer can can be used as a primer-sealer when cut with more reducer (after body work or using a polyester sanding primer). Thank you again!
@@fady904 Window frames I used the Dulux Metalshield etch primer that is anti-corrosion and the Dulux dura max high performance enamel which is drip free/ 2 coats dries in 30 mins - professional factory results. don't forget 120 or higher before priming and wash with acetone to clean clean clean before starting.
Thank you!!! I must have watched this when deciding on primer for an aluminum threshold. The black top coat has held up amazingly but I didn't remember which of the numerous brands I have on hand that I used. I came across this obscure ACE Primer in my arsenal and thought I remembered it out shining many others. Checked and sure enough it was your amazing test that convinced me. Now I can prime and paint 2 more French Door thresholds with confidence.
From my days of machining aluminium, it gives off back kind of dusty color, especially when wet. I think that in the tumbler it is alu oxide that is being produced.
You acknowledge knowing about other ways to treat aluminum so I'm not trying to critique or criticize(to much of that on here) just share knowledge. I'm a machinist Mate in the Navy, been stationed on various ships over the last 15 years in engineering. Lots of experience with paint coatings and corrosion of various aluminums and steels. I'm always looking and seeing what works compaired to theory and instruction. The best coating I've seen so far is type 3 anodizing, i.e. sailing winch drums. Two fishing reel manufacturers used it that I know of, Duel(very high end, subsidiary of a racing winch manufacturer, no longer in business) and old generation daiwa sealine(from the 80s). I have a bunch of daiwas that lived for years in rod holders in constant salt spray that still have intact coatings. As long as the coating isnt broken allowing electrical current to pass and create galvanic corrosion it will last a lifetime. Simple way to test is use a multimeter on ohms, you want an open circuit between the alloy and all fasteners and mated materials. Short of anodizing, any dissimilar metals used as fasteners should be insulated, nylon washers from ace, nylon sleeves are good choices, I use them on fasteners for alloy trailers to prevent the white death. For blind holes, countersunk machine screws, etc tefgel is the best product available in the u.s. I've seen, just be aware it acts like a thread lubricant and isnt tolerant of high heat. For regular painting of aluminum, it's like any thing. 90% time is spent in prep. This prep is de oxidize, de smut, etch and prime. Bonderite 33 first, triple rinse distilled(!!!) Water, alodine 1001, triple rinse distilled(!!!) Then prime, 2 part epoxy primer(lots of choices, many the same) then a 2 part polyurethane. I have left out the safety concerns (chromic acid, polyurethane hazards) because if you get this far you should be looking at that as well. Use appropriate gear and common sense... I bring all this up because if your aluminum is exposed to coolant for metal work it will be subject to galvanic corrosion, not as bad as warm saltwater but if you use that system it will last! For an easier at home setup I've had luck (application method depends on size) with sanding 80 grit(I love my festool rotax) distilled water in a Garden sprayer to rinse, phosphoric acid to etch and SEM primer or better go with epoxy. Where did you get the ram for your down feed on the power saw? P/N Model?? If you could answer. Anyhow, great work! This is why I love youtube. To many people worry overly about production/editing for catchy videos and views. I'm looking for information/knowledge/examples for my own use. Thanks for taking the time to make the video!
so used a wire wheel to knock off the paint on an aluminum boat was that a NO NO? gonna prime and paint most of it. Does 80 grit come out smooth on the paint job?
I worked in automotive making aluminum crash management parts, some of those were coated or plated, for certain they have to "key" the surface so that the plating sticks. I am curious if this translates to paints as well, like the "patina" version here has some characteristics of "keying" to help the paint stick to the surface.
The reason the parts turn black is explained in two ways. To understand that, one needs to remember that aluminum "rusts" like iron, just not continuously. The Oxygen layer that forms creates a hard, clear, protective barrier. That Aluminum Oxide barrier prevents paint from sticking (hence etching). The 2 things that cause color in aluminum (especially black) are this: acids, detergents, etc., causing pores changes and thickness of the oxidizing layer (which can become greater in surface area due to pitting or scratching). Aluminim forms a hexagonal cell-like layer with a pore in the middle. Pore distance affects refraction. Here's a tech article portion on the process: "Different colors can be explained by different degrees of reflection and absortption of sunlight components by oxide films and the aluminum surface. White light has different components which can create a spectrum of colors either naturally (rainbow) or in a laboratory with the help of diffraction or dispersion. If the oxide film does not absorb any component of light and all components are evenly reflected by the aluminum surface then the film looks colorless (white). If oxide film absorbs all components of light without discrimination then the film looks black. If a specific component of light is absorbed better than others, then the combination of reflected components without the absorbed one will create a non-white color."
Great video. Just what I needed for an aluminum painting project. I'd have to agree. My thought is that something in the detergent caused, helped or aided in the "gray patina" you were asking about.
As a heads-up to anyone using Dupli-Color self etching primer, our local auto body supply shop informs me that it must be covered with a "blocker', another coat of ordinary primer, or it will attack and bubble the topcoat in about a years time. And he was so right because I had already painted something without the blocker and it got screwed up and rough after awhile.
You’re saying to prime over the self etching primer before painting?? Ive heard it said to sand after the first coat of self etching then apply a second coat.
Aluminum is very hard to paint I have a project that I'm working on and I tried to paint it and the paint you could just doesn't take much to scrape it off with your finger nail so I stripped it off and I picked up some vinegar about a gallon and I put it in a pail and I let it sit the aluminum sit in the pail and I hooked a battery charger up to to one one part of the aluminum and I had another piece of aluminum in the pail and I let it sit there for about a couple hours and I it formed a fuzzy coating on the little part that I wanted to paint I use some DuraCoat self-etching primer and some dura coat regular paint it seems that I can't scratch it off I'll have to see how it stands up
Thanks for this! I’m using the 1” square aluminum tubing for a project on the outside of my house, so it must be painted. I can’t tumble it but I can surely sand it. Then acetone. Then Ace primer. Then topcoat (colormatched Rustoleum in a can.) Yes?
Great video, I came across a product called POR 15 and I got it as a kit that came with a degreaser and acid for etching and the metal first then you washer it off and use the POR 15 which turns into a ceramic like coating. Its the best I've ever use.
From past experience, it seems that any water/detergent (dish soap, simple green etc etc) mix will patina aluminum. For best results, clean aluminum by sanding then wipe down with acetone to get the best adhesion results.
Do you tumble in Zep Purple or Simple Green? Both those will darken aluminum. I have not seen it get that dark. It may be your removing the oxide coating and exposing the bare aluminum which is much more reactive. Anyways, it seemed to help hold the paint. You may want to wash your media after the paint.
I was brought up priming alum with zinc oxide or chromide. The other day i was told never to use those on aluminum as it is acidic and will corrode the metal. Ive done airplane parts with it for decades. Ive got the same cardboard work bench cover. Ill be interested to see the follow up video in a couple of years to see which primers and paints hold
Thanks great information. For parts where its not affordable to anodize, I have been using the chem-film coating. For small quanity use I found 1 gallon jugs of it intented for air-craft use. Can you compire primer-paint to chem-film?
I have an aluminum post covering a wood post on my concrete screened porch at the base. Would I scrape off the rusted aluminum part before I treat it with something like Rust Reformer?
The dishwashing liquid you add to the tumbler may have phosphoric acid or caustic soda in the blend which will darken the 6061 ,the paint will stick better to the etch surface
Well it looks like the pores the media release “gunk” plus the tank walls are causing the issue. As you continue to tumble the part is creates a ruff surface that allowed the paint to adhere better. A light acidic solution could remove the “patina”.The only other solution would be to Anodizing -it protects them for saline corrosion agents as well as abrasion. Additionally, they can be tinted in many different colours to suit your application.
Big thumbs up for this! I am curious if the results would be the same if each piece was put in separately for only about 20-30 mins at a time. I’m thinking the only difference might be in the products that lost 50% or less in this test. The other products would probably be about equal results. Either way, thanks a ton for sharing your experiments!
Thank you so much for sharing this . Now I have question I have small bar of aluminum and I want to dip it in solution ( polymer) it has green color. What should I do for the aluminum bar to make the polymer color stick on it ? is there any rep steps ? should I use the primers code too ?
Thanks for doing this, it's awesome information. I would be interested in recreating the test, only painting over the primer this time. I'm curious as to how well the paint holds onto the primer under that extreme punishment
I'd like to see the pieces sanded/roughed up first as well, which increases adhesion. When I do my nails, we rough up the surface of the nail with 100 or 180 grit to scuff the surface so nail polish adheres better, and the same principle applies to painting other smooth surfaces.
Since the entire point of priming the aluminum is to prepare it for painting, it seems completely obvious to me that paint durability is the test that needed to be done. Yet, that's not what we got.
I'm pretty sure the issue of turning the aluminum dark is from the pH of the soap/water mixture. I've run into this issue using Simple Green in an ultrasonic parts cleaner when cleaning motorcycle calipers and they were turned very dark, almost black. Simple Green has versions that are safe for aluminum: "Simple Green Extreme Aircraft/Precision Cleaner".
@@terryzak1742 what if I want to turn my aluminum black rather than paint it would spraying it with Simple Green hurt anything? Just wanted to get you answer sounds like you have had some experience with this. I have an aluminum skid plat I want dark in color rather than the bright aluminum color. If you have any other ideas that would be helpful.
@@kellymiller3136 My apologies for not getting back to you sooner. I think the strength of the Simple Green solution used, temperature of the ultrasonic cleaner bath, material and its finish, and duration in the cleaner are all factors. Best guess would be to try a sample piece and see how it comes out. Then dry it off to see how it looks and if that oxide will stay on there.
I think you would have had a better comparison by roughing the extruded alum first (which is what your deburring did to the patina version and really should be done to alum before painting anyway)
Thanks for this video! If you ever decide to do a second round, please consider including: Moeller ‘Zinc Primer’ which is specifically designated for Aluminum. Also, Rustoleum apparently has an Aluminum primer now.
gets darks cause is the natural byproduct of the aluminum oxidation process. smut showed it to contain condensed magnesium and aluminum, so it appears that magnesium may be the main culprit.
Primer is probably sticking to the patina one better because there are millions of little "scratches" on it just like sanding. So the primer can grab on easier. Also, it probably cleans off a lot of oil and other stuff on the aluminium.
Love the video! I would love if you could expand on this idea with other primers and different tests. Primers such as the 2k Epoxy primers in a can, Zinc Chromate primer, Zinc phosphate primer, and the other hard-hitters. And then do corrosion tests, scratch tests. And to expand on the etching of aluminum process, like vinegar to BONDERITE. Just stuff I haven't seen in any other youtube video. Thanks!
Thanks for your great video!!! What about painting a commercial aluminum railing that already has a coat of shiny paint on it? treated as if a bare metal?
Thanks for this nice, thorough comparison! I'm painting some extruded aluminum handles for my kitchen cabinets. I'm priming them with the Rustoleum self-etching primer, then with their appliance epoxy black paint. I don't expect them to see nearly the abuse that the vibratory cleaner inflicted on your test subjects, so hopefully they'll last for a long time.
I believe it is pronounced PATINA with a P, and it comes from the oxidization of aluminum due to the cavitation of the water on the surface of the aluminum. Same thing happens to aluminum trailers, boats etc. Excellent video, thank you!
I couldn't find a clear answer for my problem until now, hope you will help me: I have an aluminum headboard that had an ugly brown paint on it, there was no rust at all. I scraped the paint off completely, sanded lightly, and washed it with a mild soap.
Then, I painted it with Rust Oleum Gold Metallic Accents - did not prime it...! When I checked, I saw two tiny bubbles on it, and I tried to remove them with my finger, and I got them out, but also peeled the area. It was so easy. Now, I am afraid to touch it! I thought by using Rust Oleum Gold Metallic Enamel on the top of it I can make it stronger - Please, could you advise me? Thank you.
I have had terrible results on both metal and wood, if primer isn't used first, , , Even the 2-in-1 primer/paint combo sucks without primer, whether it's wood or metal.
Request same experiment on various spray paints.. great experiment. What paint would work best on triple track storms. Where the sash slides against the frame. Which paint will work when the sash slides against the frame channel?
Thanks for this video. It's very helpful. I have used a different primer on other metals like black iron pipe with great results. I have yet to try it on aluminum. I wonder how it would hold up. It's the Rust-Oleum Stops Rust Universal Bonding Primer, White.
Im curious if you scuffed up the aluminum finish before priming them? If not i think youll find youll get better results by doing so. Then cleaning with carb cleaner or degreaser then priing and giving it 24 hours to cure. Even put under heat for a bit. Very cool modification to the bandsaw would have been nice cutting EMT on job sites vs a milwaukee with one hand and a 4" pipe across your lap holding it with one hand and your crotch.
Do you have any recomendation on prep, prime, and painting an aluminum engine block? I was considering using the self etch primer but after looking at your video seems like the ace hardware rust stop is better.
Dang, I wish there was a can of VHT's etching primer in this video lol. Priceless info, and no fluff. Awesome video man, I just can't believe how much better the Ace store brand did than the rest.
An ok test for a home shop. I've got to wonder though how much of these get vibrated to the bottom because they are heavier than the media and thus would not get as much abrasion on one side which could / would skew the final results. PS..love the SawCyl.. I have that bandsaw and use it a lot so Id like to get one soon.
I think with aluminum you have to get rid of the hard oxidation scale for the acid in self etching to do anything. The catch is now you've already roughed up the surface so normal primer will also work. At the end of the day, self etching is only worth it for extreme corrosion or abrasion applications, then it's usually combined with a zinc compound, and you still need to abrade the surface first.
I have used an expensive auto paint store primer on clean unetched aluminum for my airplane and had the paint peel off. I thought I should have used zinc chromate primer, which you didn't review, but maybe that is good.
I think the most important "lesson" here is that you ought to stick with the patina version of that alumimum part for your band-saw lifter! The durability of that patina is amazing.
You will always run into to aluminum oxide. But that degree of dark aluminum oxide come from a chemical reaction between the aluminum and the dish soap. It can actually act as a protective layer if done the right way.
Thanks, I wish I saw this before today. Just used Dynaseal to coat the inside of my aluminum hitch toolbox to keep my tools from getting aluminum all over them. I already had the dynaseal, so sanded with 220 and laid it on. If it doesn't stay ill try the ACE. 👍
Upon exposure to the air, bare aluminum develops a thin layer of natural oxide. This patina layer is thin, transparent, tough, and protects the aluminum from corrosion. From GSA (General Services Administration).
Good first run and thanks for doing it, however I don't think this was a great test. You didn't follow the prep instructions for the individual products, which at-least for the self-etch primer would have had you sand the surface with an appropriate grit sandpaper. Aluminum oxidizes rapidly - without removing that oxidation layer (+ the mechanical bond from the rough surface) the primer isn't going to adhere very well - this is what Alodine is used for. I think it would be a lot more interesting seeing a comparison of properly prepped surfaces of self-etch primer vs alodine+primer vs 2k epoxy primers. Again, though following the surface prep per each product's TDS. Also your vibratory test is a little bit too harsh, maybe a shorter time period or a slightly less abbrasive media and then go up from there.
Great content ! For Rustoleum, their specific Aluminum Primer might’ve been of more interest than the Rustoleum 2x Ultra Cover tested. Big Surprise on the Ace Rust Stop. Thanks for the Test !
@@nebadawnengineering8018 I tried it for 40 minutes with my aluminum parts an it did not get a patina. Any suggestions? I’m going to try hot water next
painted aircraft and missles for the USAF for several years. Used zinc cromate primer on all aluminum to prevent the blackening which is corrosion. Not sure that primer is even available now because of its composition.
That black-ish patina on your aluminum stock is probably due to silicon, copper, etc. contaminants in the aluminum mix oxidizing after the vibratory media has removed a lot of the base aluminum stock. The various "grades" of aluminum have various amounts of contaminants in them depending on the type. For example 1xxx is almost pure aluminum, and the amount of contaminants goes up with each grade designation, e.g. 1xxx has the least and 7xxx has the most. Your stock is 6xxx so it has quite a bit of other stuff in the mix.
Interesting, but not sure how useful this information is. How many people are going to put something they have primed for additional painting in a vibrator for an hour?
Excellent! And at the end there you say this wasn’t scientific, but as a PhD student, I’d say this was scientific. You had a blind hypothesis (not knowing what to expect). You had a method (all pieces were painted and cured at the same time, and run through the machine at the same time). You had steps in your method. You had a control piece, and an experiment group. You produced a set of results. You had a conclusion. That sir, is science. Excellent!
Thumbs up for no music, no filler bs.
Absolutely 1000% thumbs up for no music!!!!!!
Great video. No unnecessary elevator music, barking dogs or air compressor tools making noise. This was a well thought out test and comparison. Well done.
There was a crying dog near the beginning.
Thanks for doing this test! You have contributed to the DIY body of knowledge and we all owe you a big thanks for this!
this video is freaking pricless.... seriously god bless this man
This is literally the best “how to” video on TH-cam! STRAIGHT to the point, extremely clear information Without rambling on for 20 minutes! Now, if you could just post some grwm how to make up videos, that would be great 🤣 lol
FWIW. My understanding is that bare untreated aluminium needs to have an etch primer applied lightly before applying a top coat of epoxy and allowing the epoxy to cure for 7 days. The etch primer has an acid in it that causes the aluminium to have a micro-rough surface which allows the expoxy to grip the surface.
Nice job. I'm starting a project that requires painting some aluminum and you've helped me a lot in terms of selecting a paint, thanks!
I'm killing myself trying to get paint to stick to some aluminum frame channels. I tried sanding, SE primers, different paints and there is always a spot somewhere peeling off. I'm heading down to Ace tomorrow morning. Thanks.
Excellent video and well done with good presentation on the results. I thought an hour in the deburirng machine would have removed the primer on all of the samples and the test would have been inconclusive - boy, was I wrong. Based on your results, I'm going for the ACE Primer - Thanks again!
Unfortunately, I have no value-able input on what causes the dark patina.
All great info. no music, no bullshit. 10/10 mate.
My understanding on paint is that any enamel that contains ammonia creates a chemical reaction between the paint and the aluminum substrate that prevents proper adhesion. I've had very good luck with aluminum prepped with a 80-100 grit sandblaster and etching primer.
Thank you for this video. I've done some similar comparisons of primers as part of a motorcycle restoration project, although I didn't use a tumbler. While not a rattle-can, I settled on Eastwood's Epoxy Primer. It's Isocyanate-free, lays down smooth, gets great adhesion, and is incredibly hard. Sanding out a run is a real chore. I use a small Iwata HVLP gun. The same primer can can be used as a primer-sealer when cut with more reducer (after body work or using a polyester sanding primer). Thank you again!
Great information. I need to paint my out door aluminum window frames. I think they were factory painted white. Not sure what method was used.
If you are painting bare aluminum use 120 grit or higher for good adhesion and use self etching primer if you are going to prime first.
Which spray paint should I use after applying the primer?
@@fady904 what spray paint did you end up using?
@@zlab1904 I primed first with Rust-Oleum Primer Pintura Base Adhesion Promoter, then I used Metal Cast Anodized Coating from Dupli.Color.
@@fady904 Window frames I used the Dulux Metalshield etch primer that is anti-corrosion and the Dulux dura max high performance enamel which is drip free/ 2 coats dries in 30 mins - professional factory results. don't forget 120 or higher before priming and wash with acetone to clean clean clean before starting.
Thanks. I found two cans in my garage and was curious if they would work on rust spots on a truck. Good information.
Thank you!!! I must have watched this when deciding on primer for an aluminum threshold. The black top coat has held up amazingly but I didn't remember which of the numerous brands I have on hand that I used. I came across this obscure ACE Primer in my arsenal and thought I remembered it out shining many others. Checked and sure enough it was your amazing test that convinced me. Now I can prime and paint 2 more French Door thresholds with confidence.
From my days of machining aluminium, it gives off back kind of dusty color, especially when wet. I think that in the tumbler it is alu oxide that is being produced.
very nice work this is the kind of thing that is hard to do, your work is appreciated.
You acknowledge knowing about other ways to treat aluminum so I'm not trying to critique or criticize(to much of that on here) just share knowledge. I'm a machinist Mate in the Navy, been stationed on various ships over the last 15 years in engineering. Lots of experience with paint coatings and corrosion of various aluminums and steels. I'm always looking and seeing what works compaired to theory and instruction. The best coating I've seen so far is type 3 anodizing, i.e. sailing winch drums. Two fishing reel manufacturers used it that I know of, Duel(very high end, subsidiary of a racing winch manufacturer, no longer in business) and old generation daiwa sealine(from the 80s). I have a bunch of daiwas that lived for years in rod holders in constant salt spray that still have intact coatings. As long as the coating isnt broken allowing electrical current to pass and create galvanic corrosion it will last a lifetime. Simple way to test is use a multimeter on ohms, you want an open circuit between the alloy and all fasteners and mated materials. Short of anodizing, any dissimilar metals used as fasteners should be insulated, nylon washers from ace, nylon sleeves are good choices, I use them on fasteners for alloy trailers to prevent the white death. For blind holes, countersunk machine screws, etc tefgel is the best product available in the u.s. I've seen, just be aware it acts like a thread lubricant and isnt tolerant of high heat.
For regular painting of aluminum, it's like any thing. 90% time is spent in prep. This prep is de oxidize, de smut, etch and prime. Bonderite 33 first, triple rinse distilled(!!!) Water, alodine 1001, triple rinse distilled(!!!) Then prime, 2 part epoxy primer(lots of choices, many the same) then a 2 part polyurethane.
I have left out the safety concerns (chromic acid, polyurethane hazards) because if you get this far you should be looking at that as well. Use appropriate gear and common sense...
I bring all this up because if your aluminum is exposed to coolant for metal work it will be subject to galvanic corrosion, not as bad as warm saltwater but if you use that system it will last!
For an easier at home setup I've had luck (application method depends on size) with sanding 80 grit(I love my festool rotax) distilled water in a Garden sprayer to rinse, phosphoric acid to etch and SEM primer or better go with epoxy.
Where did you get the ram for your down feed on the power saw? P/N Model?? If you could answer.
Anyhow, great work! This is why I love youtube. To many people worry overly about production/editing for catchy videos and views. I'm looking for information/knowledge/examples for my own use. Thanks for taking the time to make the video!
so used a wire wheel to knock off the paint on an aluminum boat was that a NO NO? gonna prime and paint most of it. Does 80 grit come out smooth on the paint job?
I worked in automotive making aluminum crash management parts, some of those were coated or plated, for certain they have to "key" the surface so that the plating sticks. I am curious if this translates to paints as well, like the "patina" version here has some characteristics of "keying" to help the paint stick to the surface.
Great job. Excellent analysis. Surprising outcome. Thanks for the helpful vid.
The reason the parts turn black is explained in two ways. To understand that, one needs to remember that aluminum "rusts" like iron, just not continuously. The Oxygen layer that forms creates a hard, clear, protective barrier. That Aluminum Oxide barrier prevents paint from sticking (hence etching). The 2 things that cause color in aluminum (especially black) are this: acids, detergents, etc., causing pores changes and thickness of the oxidizing layer (which can become greater in surface area due to pitting or scratching). Aluminim forms a hexagonal cell-like layer with a pore in the middle. Pore distance affects refraction.
Here's a tech article portion on the process:
"Different colors can be explained by different degrees of reflection and absortption of sunlight components by oxide films and the aluminum surface. White light has different components which can create a spectrum of colors either naturally (rainbow) or in a laboratory with the help of diffraction or dispersion. If the oxide film does not absorb any component of light and all components are evenly reflected by the aluminum surface then the film looks colorless (white). If oxide film absorbs all components of light without discrimination then the film looks black. If a specific component of light is absorbed better than others, then the combination of reflected components without the absorbed one will create a non-white color."
Great video. Just what I needed for an aluminum painting project. I'd have to agree. My thought is that something in the detergent caused, helped or aided in the "gray patina" you were asking about.
Thank you! I noticed his best choice was a "rust stop" primer
Is this now a toxic surface?
Is there products and procedure to refinish aluminum panel that has small corrosion spots on otherwise clean panel you could suggest
Zinc chromate primer. This has been well known for almost 100 years. It's sold by most boat dealers or marine supply stores and on Amazon.
Zinc chromate is hard to find lately. McMaster has it.
As a heads-up to anyone using Dupli-Color self etching primer, our local auto body supply shop informs me that it must be covered with a "blocker', another coat of ordinary primer, or it will attack and bubble the topcoat in about a years time. And he was so right because I had already painted something without the blocker and it got screwed up and rough after awhile.
You’re saying to prime over the self etching primer before painting?? Ive heard it said to sand after the first coat of self etching then apply a second coat.
@@geomanko4142 Yes, that's what the autobody supply told me and I've tried it both ways and he was right.
Primer is definitely not a top coat.
So what did you end up doing for painting your engine block? I am running into the same problem right now.
@@kesu90 I used and still use ordinary Rustoleum gray automotive primer from HD, Lowes, Wally World everywhere.
would the paint stck better to the non patina version if it was sanded before?
That's a good question since everyone that is priming then painting aluminum or metal will sand it first. Great Video!
Andy, very helpful and informative and elegant in its simplicity. Thanks
The “patina” is oxide from the detergent and water
Alodine first, then use a zinc cromate primer.
Aluminum is very hard to paint I have a project that I'm working on and I tried to paint it and the paint you could just doesn't take much to scrape it off with your finger nail so I stripped it off and I picked up some vinegar about a gallon and I put it in a pail and I let it sit the aluminum sit in the pail and I hooked a battery charger up to to one one part of the aluminum and I had another piece of aluminum in the pail and I let it sit there for about a couple hours and I it formed a fuzzy coating on the little part that I wanted to paint I use some DuraCoat self-etching primer and some dura coat regular paint it seems that I can't scratch it off I'll have to see how it stands up
Thanks for this! I’m using the 1” square aluminum tubing for a project on the outside of my house, so it must be painted. I can’t tumble it but I can surely sand it. Then acetone. Then Ace primer. Then topcoat (colormatched Rustoleum in a can.) Yes?
Great video, I came across a product called POR 15 and I got it as a kit that came with a degreaser and acid for etching and the metal first then you washer it off and use the POR 15 which turns into a ceramic like coating. Its the best I've ever use.
Correct, the POR, is Pour Over Rust.
Great for car frames and trailers.
Thank you for posting this video sir. You just saved me quite a bit of time and money with this primer research and testing.!!
Thanks for what you've done 5 years ago for us
From past experience, it seems that any water/detergent (dish soap, simple green etc etc) mix will patina aluminum. For best results, clean aluminum by sanding then wipe down with acetone to get the best adhesion results.
Agree 100 percent on the soap
Do you tumble in Zep Purple or Simple Green? Both those will darken aluminum. I have not seen it get that dark. It may be your removing the oxide coating and exposing the bare aluminum which is much more reactive. Anyways, it seemed to help hold the paint. You may want to wash your media after the paint.
The soap I added was Polmolive dish soap.
I was brought up priming alum with zinc oxide or chromide. The other day i was told never to use those on aluminum as it is acidic and will corrode the metal. Ive done airplane parts with it for decades. Ive got the same cardboard work bench cover. Ill be interested to see the follow up video in a couple of years to see which primers and paints hold
Thanks great information. For parts where its not affordable to anodize, I have been using the chem-film coating. For small quanity use I found 1 gallon jugs of it intented for air-craft use. Can you compire primer-paint to chem-film?
I have an aluminum post covering a wood post on my concrete screened porch at the base. Would I scrape off the rusted aluminum part before I treat it with something like Rust Reformer?
The dishwashing liquid you add to the tumbler may have phosphoric acid or caustic soda in the blend which will darken the 6061 ,the paint will stick better to the etch surface
That make a lot of sense. Thanks
Yep! That's what I was thinking. As soon as he said dish soap, I said, "Bingo! Phosphates!"
@@tommacknight1227 is the dark surface from the tumbler toxic?
Well it looks like the pores the media release “gunk” plus the tank walls are causing the issue. As you continue to tumble the part is creates a ruff surface that allowed the paint to adhere better. A light acidic solution could remove the “patina”.The only other solution would be to Anodizing -it protects them for saline corrosion agents as well as abrasion. Additionally, they can be tinted in many different colours to suit your application.
How about spraying on clear lacquer on bare aluminum? Would that hold up better?
Andy, thank you so much for making this video! I’ve had great luck with Ace Paint and glad to know the primer preformed they best.
Big thumbs up for this! I am curious if the results would be the same if each piece was put in separately for only about 20-30 mins at a time. I’m thinking the only difference might be in the products that lost 50% or less in this test. The other products would probably be about equal results. Either way, thanks a ton for sharing your experiments!
Thank you so much for sharing this . Now I have question I have small bar of aluminum and I want to dip it in solution ( polymer) it has green color. What should I do for the aluminum bar to make the polymer color stick on it ? is there any rep steps ? should I use the primers code too ?
Learning to paint textured aluminum handles for a knife 🗡️ a small project but I appreciate you posting this. Now I know how to do this the right way
Thanks so much for taking 6the time for this test and posting the video. Exactly what I needed, thank you!
Thank you for making this video. Its simple to the point and your open to others input. These are the videos that I like to see.
Thanks for doing this, it's awesome information. I would be interested in recreating the test, only painting over the primer this time. I'm curious as to how well the paint holds onto the primer under that extreme punishment
I'd like to see the pieces sanded/roughed up first as well, which increases adhesion. When I do my nails, we rough up the surface of the nail with 100 or 180 grit to scuff the surface so nail polish adheres better, and the same principle applies to painting other smooth surfaces.
Since the entire point of priming the aluminum is to prepare it for painting, it seems completely obvious to me that paint durability is the test that needed to be done. Yet, that's not what we got.
@@Josef_R Ya, i was thinking that too.
What dishwash liquid do you use when tumbling? Could that lead to the dark patina?
I'm pretty sure the issue of turning the aluminum dark is from the pH of the soap/water mixture. I've run into this issue using Simple Green in an ultrasonic parts cleaner when cleaning motorcycle calipers and they were turned very dark, almost black. Simple Green has versions that are safe for aluminum: "Simple Green Extreme Aircraft/Precision Cleaner".
@@terryzak1742 what if I want to turn my aluminum black rather than paint it would spraying it with Simple Green hurt anything? Just wanted to get you answer sounds like you have had some experience with this. I have an aluminum skid plat I want dark in color rather than the bright aluminum color. If you have any other ideas that would be helpful.
@@kellymiller3136 My apologies for not getting back to you sooner. I think the strength of the Simple Green solution used, temperature of the ultrasonic cleaner bath, material and its finish, and duration in the cleaner are all factors. Best guess would be to try a sample piece and see how it comes out. Then dry it off to see how it looks and if that oxide will stay on there.
I think you would have had a better comparison by roughing the extruded alum first (which is what your deburring did to the patina version and really should be done to alum before painting anyway)
Thanks for your test as its the first in my education about the painting of aluminum. Impressive I'd say.
Thanks for this video! If you ever decide to do a second round, please consider including: Moeller ‘Zinc Primer’ which is specifically designated for Aluminum. Also, Rustoleum apparently has an Aluminum primer now.
I would also like to see the self etching primers sprayed over painted aluminum.
gets darks cause is the natural byproduct of the aluminum oxidation process. smut showed it to contain condensed magnesium and aluminum, so it appears that magnesium may be the main culprit.
Thank you for taking the time, and spending the money to do this video!
What primer would work over a powder coated surface to help paint stick to it ?
Primer is probably sticking to the patina one better because there are millions of little "scratches" on it just like sanding. So the primer can grab on easier. Also, it probably cleans off a lot of oil and other stuff on the aluminium.
Love the video! I would love if you could expand on this idea with other primers and different tests. Primers such as the 2k Epoxy primers in a can, Zinc Chromate primer, Zinc phosphate primer, and the other hard-hitters. And then do corrosion tests, scratch tests. And to expand on the etching of aluminum process, like vinegar to BONDERITE. Just stuff I haven't seen in any other youtube video. Thanks!
OK. 🤣
Thanks for your great video!!! What about painting a commercial aluminum railing that already has a coat of shiny paint on it? treated as if a bare metal?
Thanks for this nice, thorough comparison!
I'm painting some extruded aluminum handles for my kitchen cabinets. I'm priming them with the Rustoleum self-etching primer, then with their appliance epoxy black paint. I don't expect them to see nearly the abuse that the vibratory cleaner inflicted on your test subjects, so hopefully they'll last for a long time.
I believe it is pronounced PATINA with a P, and it comes from the oxidization of aluminum due to the cavitation of the water on the surface of the aluminum. Same thing happens to aluminum trailers, boats etc.
Excellent video, thank you!
I couldn't find a clear answer for my problem until now, hope you will help me:
I have an aluminum headboard that had an ugly brown paint on it, there was no rust at all. I scraped the paint off completely, sanded lightly, and washed it with a mild soap.
Then, I painted it with Rust Oleum Gold Metallic Accents - did not prime it...!
When I checked, I saw two tiny bubbles on it, and I tried to remove them with my finger, and I got them out, but also peeled the area. It was so easy. Now, I am afraid to touch it!
I thought by using Rust Oleum Gold Metallic Enamel on the top of it I can make it stronger - Please, could you advise me?
Thank you.
I have had terrible results on both metal and wood, if primer isn't used first, , , Even the 2-in-1 primer/paint combo sucks without primer, whether it's wood or metal.
Request same experiment on various spray paints.. great experiment. What paint would work best on triple track storms. Where the sash slides against the frame. Which paint will work when the sash slides against the frame channel?
Thanks, Great video, best true life test I have seen. I will be showing this to my class.
I came here to learn. And I did. Thank you. Have been using the Rust Oleum self etching. And now I know for sure it is not worth carrying home.
Thanks for this video. It's very helpful. I have used a different primer on other metals like black iron pipe with great results. I have yet to try it on aluminum. I wonder how it would hold up. It's the Rust-Oleum Stops Rust Universal Bonding Primer, White.
i have a primer for aluminum and galvanized and stainless steel.. can i use it on normal steel also?
Im curious if you scuffed up the aluminum finish before priming them? If not i think youll find youll get better results by doing so. Then cleaning with carb cleaner or degreaser then priing and giving it 24 hours to cure. Even put under heat for a bit. Very cool modification to the bandsaw would have been nice cutting EMT on job sites vs a milwaukee with one hand and a 4" pipe across your lap holding it with one hand and your crotch.
Awesome. I've got my answer on painting my aluminum rims.
Do you have any recomendation on prep, prime, and painting an aluminum engine block?
I was considering using the self etch primer but after looking at your video seems like the ace hardware rust stop is better.
I used Sherwin-Williams Self Etching Gray Primer (904?) for years and found it great. now I cannot find it ☹
Dang, I wish there was a can of VHT's etching primer in this video lol. Priceless info, and no fluff. Awesome video man, I just can't believe how much better the Ace store brand did than the rest.
Would the Ace primer work on aluminum fascia that has sections where the white paint has peeled off or would it be best to use the etching primer???
great video, I use the rustoleum for the self etching , and its a bit of high building as well
An ok test for a home shop. I've got to wonder though how much of these get vibrated to the bottom because they are heavier than the media and thus would not get as much abrasion on one side which could / would skew the final results. PS..love the SawCyl.. I have that bandsaw and use it a lot so Id like to get one soon.
I think with aluminum you have to get rid of the hard oxidation scale for the acid in self etching to do anything. The catch is now you've already roughed up the surface so normal primer will also work. At the end of the day, self etching is only worth it for extreme corrosion or abrasion applications, then it's usually combined with a zinc compound, and you still need to abrade the surface first.
I have used an expensive auto paint store primer on clean unetched aluminum for my airplane and had the paint peel off. I thought I should have used zinc chromate primer, which you didn't review, but maybe that is good.
Incredibly valuable. Thanks for this research.
I think the most important "lesson" here is that you ought to stick with the patina version of that alumimum part for your band-saw lifter! The durability of that patina is amazing.
Aluminum oxide is nearly as hard as diamond
Nice experiment. Good Job! Thanks for this.
You will always run into to aluminum oxide. But that degree of dark aluminum oxide come from a chemical reaction between the aluminum and the dish soap. It can actually act as a protective layer if done the right way.
Thanks, I wish I saw this before today. Just used Dynaseal to coat the inside of my aluminum hitch toolbox to keep my tools from getting aluminum all over them. I already had the dynaseal, so sanded with 220 and laid it on. If it doesn't stay ill try the ACE. 👍
You are a dying breed my friend thank you so much!
He looks very much alive to me.
My mum's gravy sticks to anything, once it dries, you will never get it off. :-)
PS, The lumps might be a problem though!
ha!
🤣🤣
Great video sir, thank you for your time & effort.
Wow, that was a great video. You’ve just helped me to chose primer.
Upon exposure to the air, bare aluminum develops a thin layer of natural oxide. This patina layer is thin, transparent, tough, and protects the aluminum from corrosion. From GSA (General Services Administration).
Good first run and thanks for doing it, however I don't think this was a great test. You didn't follow the prep instructions for the individual products, which at-least for the self-etch primer would have had you sand the surface with an appropriate grit sandpaper. Aluminum oxidizes rapidly - without removing that oxidation layer (+ the mechanical bond from the rough surface) the primer isn't going to adhere very well - this is what Alodine is used for. I think it would be a lot more interesting seeing a comparison of properly prepped surfaces of self-etch primer vs alodine+primer vs 2k epoxy primers. Again, though following the surface prep per each product's TDS. Also your vibratory test is a little bit too harsh, maybe a shorter time period or a slightly less abbrasive media and then go up from there.
Thanks for the comparison. I need to paint some aluminum motorcycle parts tomorrow so may just go with the ACE primer.
Great content ! For Rustoleum, their specific Aluminum Primer might’ve been of more interest than the Rustoleum 2x Ultra Cover tested. Big Surprise on the Ace Rust Stop.
Thanks for the Test !
I love all of Ace spray paints, thanks for taking the time to make this video!
No need to sand or strip first ?
Thanx! Aluminum has always been a bear to get a nice finish on on small significant parts.
What color Palmolive soap did you use?
It was green.
@@nebadawnengineering8018 oh perfect! That’s the one I bought. How is that patina holding up?
@@nebadawnengineering8018 I tried it for 40 minutes with my aluminum parts an it did not get a patina. Any suggestions? I’m going to try hot water next
@@BackyardBroadheads I used a Harbor Freight Vibrator with a black plastic shaker container. The black may have come from that. I am not sure.
Rust-oleum has an aluminum-specific primer which is different than this more general self-etching product.
Unfortunately, I only see it for sale in packages of six cans.
painted aircraft and missles for the USAF for several years. Used zinc cromate primer on all aluminum to prevent the blackening which is corrosion. Not sure that primer is even available now because of its composition.
Reasonable test, surprising results, just the kind of thing I like to see.
That black-ish patina on your aluminum stock is probably due to silicon, copper, etc. contaminants in the aluminum mix oxidizing after the vibratory media has removed a lot of the base aluminum stock. The various "grades" of aluminum have various amounts of contaminants in them depending on the type. For example 1xxx is almost pure aluminum, and the amount of contaminants goes up with each grade designation, e.g. 1xxx has the least and 7xxx has the most. Your stock is 6xxx so it has quite a bit of other stuff in the mix.
Thanks for a great video and a great test! Exactly what I was looking for.
Thanks for the well done test. Headed to Ace tomorrow.
Interesting, but not sure how useful this information is. How many people are going to put something they have primed for additional painting in a vibrator for an hour?