Speedtoys

Has anyone looked at base coatings like Alodine as a base treatment before PC'ing cast parts?

With that process, of course comes acid etching to clean the somewhat porous surface of a cast part.

Just wondering if anyone has had PC issues with long term adhesion.


Thanks!

Mrmerlin

what parts are you trying to coat?
I had my intake and cam covers PCed thats it,
just bead blasted them first

Speedtoys

Thats what I would normally do, but you never have a clean alum surface to adhere to..it oxidizes too fast.

The question came from working on aviation repairs..so I was just wondering.

namasgt

the intake and valve covers are Magnesium not Aluminum, fancy cars you know.
what ever that etching stuff is, will probably destroy magnesium.

GregBBRD

Alodine works fine on the intake and valve covers. I thinbk that it oxidizes the surface and makes it more stable. If you take a freshly bead blasted surface, it turns it "dark" like the magnesium has been sitting around for a few years.

Alodine on aluminum is pretty standard stuff.

Speedtoys

Alodine makes a system for anything it seems, including a specific magnesium alloy kit, we have it at the shop.

I'll search..and see if I still cant find out what the specific Al or MG alloy these parts are.

Speedtoys

It creates a chromate coating..doesnt prevent wear, but its an awesome bonding surface for paint or PC..whereas the always oxidized alum surface isnt so much.

Giovanni

I've powercoated 3 sets of 928 intake and I never had a problem. Strip it, clean it, outgass it and powdercoat it.

cobalt

Magnesium requires a chemical conversion to be performed to protect and prepare the surface. Check AMS-M-3171 for more specifics.

Jim Devine

Look into Dow #7 for magnesium. It's a great look
by itself. The original Halibrand mag wheels were
Dow 7 coated (golden brown). Over a polished surface it's even better.

See if you can get a scrap intake or cam cover to
test with & to see if you like it.

http://www.saporitofinishing.com/pro...esium-aluminum

cobalt

I do this process on my parts and it varies for many reasons. Color can be dark or light golden to brown to gray depending on surface preparation, hardness times and temperatures used. I would still recommend coating it for use in the elements. Magnesium is better with a hard coating.

Jim M.

Plenty of people have powder coated the water bridge and the upper water outlet and both are cast aluminum. AFAIK none of them have proven to be problems with adhesion.

linderpat

Depends on the year. Early spiders are cast alum.