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NevadaZielmeister
01-29-2016, 12:22 AM
Gentlemen,

As I am placing the very final finishing touches on my build, I was curious if anyone has any experience painting aluminum parts? I understand there is a process by which you have to prepare the surface to accept paint and there are several links on the internet. I just would like to know if anyone has a link or a reference in which they personally used it to success. My plan is to paint the rear tire carrier and the rear bumper fascia on my JKUR and the thought of saving a few hundred dollars is appealing and getting the job done myself is satisfying.The Genright Rear Tire Carrier and the EVO MFG rear fascia come in bare aluminum. So any thoughts or experiences with those parts directly would also be appreciated. I thank you in advance.

Blazindevl
01-29-2016, 01:44 AM
Pretty much the same as painting steel. Wash entire surface to be painted with dawn dish soap thoroughly to remove any silicates BEFORE sanding. Sand with 200 grit paper. Wash again with dawn thoroughly. Prime with self etching primer, comes i a spray can from lowes or Home Depot. 3 light coats of primer and let cure. Sand with 1500 or 2000 grit sandpaper then wipe with very lightly soaked rag of lacquer thinner being careful not to wipe off primer. Then paint. If using a spray can just do same as primer, 3 light even coats until coverage is achieved. If using a hvlp gun or equivalent then 2 coats of base, sand with 2000 grit, wipe and apply last coat of base, let cure... Wipe with tack cloth then 2 coats of clear about 15 minutes apart ( 2nd coat heavier than the first)

Make sure you use self etching primer

kbp810
01-29-2016, 02:07 AM
No experience with painting those specific parts... but I have painted aluminum flares and a hood louvre with success.

The single most important step in painting aluminum is in the prep (of course that's true for all materials) - Aluminum sort of forms its own protective layer, and paint is not very fond of adhering to that layer... so you'll need to make sure to scuff/sand all surfaces thoroughly, then clean and dry well. When painting any metal, I also like to take a torch and lightly go over the part to make sure to draw out any remaining moisture - just make sure not to dwell in any one spot for too long, and also let it cool before starting to paint.

From there a zinc chromate primer is the way to go, followed by your paint of choice.

There are chemical processes that can also be used to get rid of the oxidation layer, but I have no experience with this in regards to painting. I used to build guitar amps, and whenever working with an aluminum chassis I would prep it with an acid etch to remove the layer and then submerge in alodine to prevent it from re-forming (which can make aluminum non-conductive)... I'd imagine the process for paint prep would be similar, but couldn't see how this would be practical to do with large parts.

Dodge4me
02-01-2016, 09:19 PM
No experience with painting those specific parts... but I have painted aluminum flares and a hood louvre with success.

The single most important step in painting aluminum is in the prep (of course that's true for all materials) - Aluminum sort of forms its own protective layer, and paint is not very fond of adhering to that layer... so you'll need to make sure to scuff/sand all surfaces thoroughly, then clean and dry well. When painting any metal, I also like to take a torch and lightly go over the part to make sure to draw out any remaining moisture - just make sure not to dwell in any one spot for too long, and also let it cool before starting to paint.

From there a zinc chromate primer is the way to go, followed by your paint of choice.

There are chemical processes that can also be used to get rid of the oxidation layer, but I have no experience with this in regards to painting. I used to build guitar amps, and whenever working with an aluminum chassis I would prep it with an acid etch to remove the layer and then submerge in alodine to prevent it from re-forming (which can make aluminum non-conductive)... I'd imagine the process for paint prep would be similar, but couldn't see how this would be practical to do with large parts.

You hit it right on. I second the alodine, then zinc chromate primer. It will last forever!
The trick is how to alodine. Helping my father build his airplane, we just used a tarp and poured it over the parts on the tarp, flipping as needed, then just hosed it off. Should not be that insurmountable.

NevadaZielmeister
02-01-2016, 09:21 PM
Thank you gentlemen for all of your help. Much appreciated.

highoctane
02-01-2016, 09:28 PM
I'm an A&P mechanic, and I've even used an alodine pen before painting aluminum and magnesium aircraft parts. Alodine is a chemical I would NOT spilled anywhere, especially my hands, and the pen is a much cleaner way to apply it. Give the MSDS a read over before using it.

http://www.aircraftspruce.com/catalog/pdf/alodine1201msds.pdf

NevadaZielmeister
02-01-2016, 09:45 PM
I'm an A&P mechanic, and I've even used an alodine pen before painting aluminum and magnesium aircraft parts. Alodine is a chemical I would NOT spilled anywhere, especially my hands, and the pen is a much cleaner way to apply it. Give the MSDS a read over before using it.

http://www.aircraftspruce.com/catalog/pdf/alodine1201msds.pdf

While I thank the application of alodine idea from the previous poster, I also questioned the entry of this material into my garage floor, ground, etc. I did find the pen you were mentioning:

http://www.amazon.com/Henkel-Aerospace-592939-Alodine-Touch-N-Prep/dp/B00OLTQOD8

But $91.32 for 4 ounces? Really?!?! That is pricey stuff. What about using a spray bottle instead, like this:

http://www.skygeek.com/henkel-alodine-1001-quart.html?utm_source=googlebase&utm_medium=shoppingengine&utm_content=henkel-alodine-1001-quart&utm_campaign=froogle&gclid=Cj0KEQiAoby1BRDA-fPXtITt3f0BEiQAPCkqQdZnIVkbh8jHjF-8cf3z9Hv0x2XPYPrY8H0JDpG0ZnQaAgJl8P8HAQ

Or maybe brush it on? Any thoughts?

highoctane
02-01-2016, 09:49 PM
While I thank the application of alodine idea from the previous poster, I also questioned the entry of this material into my garage floor, ground, etc. I did find the pen you were mentioning:

http://www.amazon.com/Henkel-Aerospace-592939-Alodine-Touch-N-Prep/dp/B00OLTQOD8

But $91.32 for 4 ounces? Really?!?! That is pricey stuff. What about using a spray bottle instead, like this:

http://www.skygeek.com/henkel-alodine-1001-quart.html?utm_source=googlebase&utm_medium=shoppingengine&utm_content=henkel-alodine-1001-quart&utm_campaign=froogle&gclid=Cj0KEQiAoby1BRDA-fPXtITt3f0BEiQAPCkqQdZnIVkbh8jHjF-8cf3z9Hv0x2XPYPrY8H0JDpG0ZnQaAgJl8P8HAQ

Or maybe brush it on? Any thoughts?

I've only used the pen since I've used it on parts that are installed in the aircraft, so spraying/dousing the area for the stuff to drip down into other areas and onto other parts was out of the question. I can't comment on other application methods since I've never used it that way. Never realized those pens are so expensive! Maybe a sponge brush would work to brush it on. Seems like the cleanest way to get it on there.

zimm
02-01-2016, 10:10 PM
I painted motorcycle wheels which were bare aluminum. We used a $50 spray gun from home depot. Used rattle can auto primer, wet sanded it, and then used NAPA automotive paint (2 part), and they came out awesome. I wouldn't try painting sheet metal, but bumpers, tubes, and smaller surfaced things are easier to hide imperfections.