Suitable primer for painting aluminium?

Hi All,

I am restoring an old Elliott pillar drill using grey primer and machinery paint bought from Stationary Engine Parts. I am using some sheet aluminium and a die cast box to hold new controls and don't really want to buy aluminium primer if I can help it.

would I be OK with grey primer if I give the aluminium a good roughing up with a wire brush first?

Many thanks,

Nick

You really need an etch primer. As the paint will eventually chip and peel off and or bubble without it.

brian

As Brian said the only way to paint aluminium is with acid etch primer with out it the paint will not adhere to aluminium or galvanised steel if it comes to that.

Bob

Thanks for the advice Bob & Brian - much appreciated.

Nick

Actually, before the advent of pre-painted aluminum sign blanks, I hand lettered and silk screened hundreds of aluminum and galvanized signs using zinc chromate primer. The signs stood up to seasonal weather changes and road blast extremely well. A light fine sanding of the metal is necessary followed by a thorough degreasing. Aluminum must be primed immediately following the preparation before new oxidation begins to form. Also, avoid fingerprints. I do know that the refinishers at the neighboring military helicopter training unit used an acid etch primer on their aircraft. Important to note that my process was not subjected to very high temperatures such as those that occur on engine cowlings..

Cheers

Bill

We used to use zinc chromate to prime galvanised handrails on ships. Haven't seen it for years

Zink Chromate primer is available on EBay and in many D I Y shops - would recommend for use on alloy

You could use 2 pack epoxy primer, its not a dangerous isocyanate paint, it doesn't need an etch primer , it will stick very well to anything you spray it on, and lastly it is very very tough.

Just for interest- Yesterday I pressure washed my home made van, all the paint on the timber peeled off, the paint on the aluminium and steel parts are still good. Timber was primed with the proper, expensive, aluminium based wood primer, the metal work slapped over with Hammerite.

Rub the job down with vinegar before applying regular primer. The vinegar etches into the ally so the primer can stick to it.

I am not sure that vinegar is the correct thing to use, an alkali is better, try washing soda or caustic soda (v. dangerous but effective), then hold in plastic gloved hand to stop finger prints. Hose down with clean water, dry over heat and prime quickly.

Frank

We used Zinc Chromate primer on all aircraft painting, and most of our aircraft were painted with two part epoxy paint. Ian S C

I agree with Ian

For some years I had a metal glider - always used Zinc Chromate as a primer on that.

Norman

You are only priming a pillar drill so find your local (proper) autopaint store and they will sell you a small tin of aerosol etch primer. Most all real autobody paint suppliers make up aerosols of almost anything on their premises nowadays.

I do this regularly as it is quick, simple and cost effective.

graham.

It may, or may not, be particularly relevant to painting but I would just mention that Phosphoric Acid [readily available in rust-treatment products like Jenolite] is an excellent etching agent when using epoxy resins on aluminium. ... But, having no primer in it, the epoxy needs to be applied very soon after etching [within about 30 seconds if possible].

MichaelG.

Here is the MSDS for Jenolite.

U-POL ACID #8 ETCH PRIMER, available from most Halford stores in the UK:- **LINK**

I've never been able to find it in stock at Halfords. An availability check said I could 'collect from 1pm Wednesday, Looks like it is an 'on demand' product.

Neil

Zinc chromate is not the safest stuff as it is a known human carcinogen

Bob

Neil

At Halfords the U-POL ACID#8 ETCH PRIMER is not normally on the shelf with the car colour paints. You need to look on the shelf with the specialist spray paints and fibreglass kits.

It is good stuff for steel and aluminium, it also does a very good job with those "difficult" materials such as brass and stainless. Now I have found it I would never consider standard primer again.

Mike