Painting aluminum

Advice
#1

I seem to remember a comment (possibly from Mike McC?) regarding pickling of aluminum rivit heads with vinegar to “age” the surface prior to painting the head.



Was I just dreaming, or is this a good idea for painting aluminum?



I am fabricating four 1/2" x 6" x 3" 6061 aluminum adaptor plates, rounded on each end and chamfered for aestetics to be mounted on a …top secret project.



I want to finish them dull black, and plan on spray painting a primer before the finish coats go on.



Would “pickling” the surfaces with cider vinegar aid in getting the primer to stick?



Jim

#2

pInting aluminum
I am no expert and am not looking to get flamed. To that end, I have painted aluminum before, lately it was an entire canoe with harbor blue topsides and gloss white from just over the waterline to bottom of hull. I steel wooled the aluminum first, then used an aluminum primer, and let it sit for two days. I lightly sanded it, and applied the paint. It looks awesome, is very durable and sticks well.

#3

Black Aircraft Aluminum Rivets
You can buy black rivets by the bag from Ocean Kayak, and several other places

#4

?
I would think today there would be some good aluminum primers out there, and I would be asking at a quality paint store.

That being said when aluminum gutters first showed up in the houseing industry we had a horible time getting paint to stick to them, untill some one came up with the idea of wiping them down with regular white viniger that you get at the grocery store, seems to be just acid enough to etch the surface so the paint would adhere.

Dennis

#5

2nd Brammy’s method
Used the same methodology for some aluminum canoe ‘beautification’.

steel wool->wipe down with acetone or lacquer thinner->apply aluminum primer->apply rustoleum paint

#6

painting aluminum
As a painter with over 30 years experience, we used to wipe down new galvanized gutters with vinegar to remove the milling oil that was on them, not so much to etch the metal. Aluminum gutters were a different story.



The problem with painting aluminum is no matter what you do to it prior to painting, whether it be sandpaper, steel wool, high pressure water washing or even sandblasting, the metal starts to oxidize immediately, causing poor paint adhesion.



The secret is, as the two previous posters mention, a good aluminum primer. Zinc Chromate is the preferred, though there may be something better nowadays, something “space age”. Just make sure the label says it’s good on aluminum.



So do what ever you want in preparation to painting, but don’t skip the primer, and then apply two coats of a good alkyd finish.

#7

Painting Aluminium
As stated, the problem of adhesion is caused by the oxide coating on the metal.



The best way is to apply an acid etch primer designed for aluminium which will chemically dissolve the oxide allowing the paint to adhear to the metal.

#8

Agree with jjoven
You can use vineger to wipe down galvanized metal before painting. This is used in place of chromic acid pickle.

For aluminum you can use zinc chromate primer which is getting harder to find due to environmental issues. A good epoxy primer works well, we use it to paint military aircraft.



BG

#9

Sound advice so far
I want these to look reasonably good, but paint touch-up as time goes by will be no problem. I just wanted to start with a good foundation to delay the inevitable touch-up painting.



Since this is a relatively small (in terms of square footage) project my paint will be from a spray can. Methinks I need to visit the local automotive emporium.



Thanks all!



Jim

#10

Professional Advice here…
http://www.finishing.com/400/35.shtml



Read this post, then ask your question there…you will receive professional advice from the finishing community.

#11

Anodizing
I’ve used a Chemical used for anodizing aluminum gun parts…have you considered that in lieu of paint?



http://astro.neutral.org/anodise.shtml



The link discusses methods for doing it at home,(in bulk I gather) but the bottle I found in a gun shop, for use in anodizing aluminum parts was a brush on and let sit for small parts.

#12

I would not recommend HF
(Hydrogen Fluoride) even if you can obtain it.



This is a very dangerous chemical & can kill you if it comes into contact with your skin inhaled or swallowed.



See this link



http://physchem.ox.ac.uk/MSDS/HY/hydrogen_fluoride.html

#13

Great idea!
Never crossed my mind. I will investigate.



Jim

#14

f&h paint
finnaren & haley has a paint called dtm (direct to metal). i used it to paint my homemade aluminum rack & it’s been over a year & paint has not peeled off. if you go to the 51st posted message on the “subaru” topic you’ll see a pcture of my black aluminum rack. good luck.

#15

Google
’painting Land rovers’ and you’ll get links to the prep/primer/paint system you need.

The primer really eats into the aluminiun for an unbelivable bond. System is ‘wet in wet’ which means you can finsish your work without having to wait for the primer to cure. You’ll need a mask with bio-filter as the stuff is dangerous if you breeze it in.

And it needs to be sprayed with HPLV gun.

But the result is an unbelievable surface-like an airliner…

#16

grumman says
"just never use copper based or cuprous-oxide paints"

What ever that means?