How to paint aluminium

I have made of aluminium quite nice switchbox dedicated for motor control.

How to paint it? It is known that most of paints do not stick to aluminium and anodizing means much troubles. Chemistry is easy enough but I really want to avoid troubles related to purchasing appropriate chemicals and making appropriate bath, all just to make an odd item looking nice.

So any paints which will stick to aluminum well?

Martin

Degrease well, then etch prime, then paint choice is the least of your problems - but choose something that works with the primer, not reacts with it.

What you need is an etch primer which are available from car shops. Then a top coat of your choice can be added after.

Brian

Use a good mask when using etch primer, preferably outdoors as it is very nasty stuff. Only needs a very light coat, then conventional primer before top coating. Colin

Question - Is it phosphoric acid in etch primer (I believe so), so, could you use a rust "eating" product such as JENOLITE which is Phosphoric acid based? MD may already have something like this in the workshop. If you do use it, don't leave it on for too long before washing it off.

This is a suggestion, others to comment before using this advice.

BobH

Try this previous thread - **LINK**

Avilable from car paint suppliers and shops in aerosol cans, works OK but use a filter mask, disgusting stuff to breathe!

why not just give it a good rub down with some steel wool before applying the paint of choice?

Michael W

Michael, this is why you can't give it arub with wire wool, taken from Phoenix Paints site

"Brass, copper, aluminium and nickel silver, in fact all non-ferrous metals should be etch primed before applying any subsequent coats of paint. These metals have an oxide layer which paints do not adhere to very well. Even if abraded with abrasive paper, the oxide layer reforms within 2 or 3 seconds!! Etch Primer has an acid in it to microscopically eat through the oxide layer and into the metal thus providing a key for the paint."

Edited By JasonB on 06/04/2018 11:00:10

Another disadvantage of wire wool is ferrous metal surface contamination which is known to reduce paint adhesion to aluminium even if otherwise properly prepared and effectively etch primed. Pretty much impossible to stop microscopic particle common off the wire wool and becoming embedded in the alloy surface or reforming oxide layer.

Clive

If you use steel wool, make sure it is stainless steel wool. The acid in etch primer is chromic acid, it used to be zinc chromate when I was in the aviation business. I think they now use Strontium Chromate.

Ian S C

Edited By Ian S C on 06/04/2018 13:40:43

This was also asked in 2015 ( by Nick_G), 2016 ( Nick T...mmm, wonder if that's not the same fellow..?) and 2017 (by Robin Graham) with all the same answers..., so this one is the 'done-it' for 2018 it seems...There were lengthy, useful answers to those queries

Sometimes a simple search on the forums does it all..

Joe

Joe

Thank goodness the question wasn't 'what lathe shall I buy?'. That's been asked about 500 times since 2015!!

True, but I really do not think painting and buying a lathe are quite the same thing..There are a few appropriate ways to paint aluminium, and yet many different lathes and configurations to buy, so those questions are timeless..

Joe

Many thanks for suggestions.

I have purchased spray etchant in specialistic shop supplying car repair businesses. Seller is very confident about its performance.

Yes, it is sometimes good idea to search older threads.

Martin

Ian SC

I have many years experience producing, testing and troubleshooting etch primers from all sorts of manufacturers in the UK. Formerly I worked for the company which introduced etch primers to the aircraft industry pre-WWII and have never found your formulation suggestions to be commercially available for use in any manufacturing or maintenance role in Europe or the Americas.

Jerry