I, like many who have posted here, have read about this "etching primer" many times, and yet have been unable to find it in the stores.  

What is it and where do you get it?  Any brand names?  

I have also read that you can etch the aluminum boxes with muriatic acid and then paint them.  Is this true?

i just built my first box and am itching to paint it but don't want it to look like shite.

Small bear electronics sells the stuff, but it's quite expensive (like $14 or something)...I don't think I've seen it anywhere else though.

I suspect that a primer containing zinc chromate would work well. The crucial thing, is to have the surface you are painting REALLY clean, just like etching a PCB, even fingerprint oils will interfere with the paint adhering. I'm not a paint expert by any means, though.

I'm in Australia, so this probably won't help, but I use the Wattyl Killrust Etch Primer - see here: http://www.wattyl.com.au/mw_index.htm. With aluminium it very readily oxidizes, and I think that this resultant oxide doesn't allow paint to bind very well. The 'etch' implies that there is some chemical reaction that allows binding to occur more easily - certainly, if I mistakenly scratch one of my boxes 95% of the time the top coat is scratched off but the primer is not!

Mike

Thanks for your replies....

I happened to be at Advance auto parts today and I checked in the paint section and they have etching primer for 4.98.  I tried it and it has worked pretty well so far.  The bad thing about it is it's olive drab instead of a lighter color, but I can live with that to save 10 bucks a can.

If you get some be careful...I didn't realize I had some on my finger and touched the back of my neck and it started burning shortly thereafter.

A further complication with boxes is that some are aluminium, and some are zinc. Some etching primers are unsuited to zinc (it will say on the can).

If you have any friends who doautobody work,they can give you a hand. Sometimes a small amount can be "siphoned" off from a large expensive can of self-etching primer. Most is geared towards aluminum, but double check first. I've been playing with the cast aluminum "project Boxes" available from MCM and Jameco. I polished one, which gave it a chrome appearance, the other I used Createx Auto Air over spray can primer. It needs tobe heat set, but lasts as well as any other automotive, solvent based paint, but it's water based, I LOVE that!