Thanks to some of our members I've seen a couple of recent threads explaining the best ways to apply cold bluing to steel.
I learned that warming the surface after degreasing will help get better results.

Any tips on the best ways to apply Aluma Black to anodized aluminum frames ? On older Airweights and Cobras the gripstraps really take a beating, finish-wise.
I am aware aluminum frames that still retain the anodizing will not suffer from lack of surface finish as dramatically as steel frames will without finish on it.

Thanks in advance.

I never had much luck with Aluma Black no matter what I did. The color was never better than a mottled dark gray and was not very wear resistant Aluminum is fundamentaly different from steel in that it developes a tenacious oxide film in seconds if the bare aluminum is exposed to oxygen.

If you don't want to have the frame re-anodized, then one of the high tech gun paints is probably a better choice. I have used Brownells Aluma-Hyde II on several Ruger 10-22's with satisfaction. It takes about a week for full cure, but once cured it is tough and very solvent resistant. Other paints or coatings that require baking are even better.

In case you want to fully restore the original finish, it can be re-anodized for not much money.

Welcome to US Anodizing is one firm( there are others) that can apply either Type II or III(hard) anodizing. I don't know which was orginally used on your revolvers, but either one is an order of magnitude better than any other finish you might put on in a home shop.

Victor at US Anodizing is a good guy and he runs a top notch company. I talked to him once about possibly reanodizing either an original AR-10 rifle or an early AR-15 Mod 601 rifle, I can't remember which.

I may try the Aluma Hide but sending the gun I have in mind to be reanodized is just not worth the expense. It's a carry gun and it's fine mechanically, but it's showing it's age at 55 years. Does have a lot of character, though

The few times I've tried the Aluma Black I got the same results you did.
I thought it might be a good idea to check here to see if I was missing something. Since it's so easy to use I may try the heat thing that helps with cold bluing surface prep.

I have to agree that the oxidation properties of aluminum vs. steel are very different.

Thanks for your reply.

I would suggest that you check the web site
Anodizing Aluminum
It gives very good instructions on home anodizing of aluminum. One thing to keep in mind is that the typical instructions to use RIT dyes is simply not a good idea. The resulting colors are not saturated, and the dye leaches out during the sealing process. CASWELL plating (Plating Kits Electroplating Kits Aluminum Anodizing Kits Powder Coating Systems Metal Polishing And Buffing Supplies - Caswell Inc.) sells dyes specifically made for anodizing, and while more expensive than some other sources, is a good resource to investigate.

All-in-all, aluminum anodizing is no more difficult than bluing, and since the acid is cooled and is at only moderate strength, it is no where near as physically dangerous as hot bluing.

If you are interested, I would advise that you practice on scrap pieces before you plunge a firearm frame into sulphuric acid and hook up direct current to it. It can be very disheartening to watch an airweight or Model 39 frame dissolve before your eyes.

Thanks for your suggestions and the links. It's more than I want to do for these guns, I only had a touch up in mind, but it's very good information.