I have been doing a lot of rust bluing lately and most of the caustic bluing I have taken to a friend and dipped there. I used to mix my own salts and had a steel tank and right now all I have are a couple of stainless steel tanks. Will caustic salts "cook off" correctly in stainless steel or should they be mild steel tanks. Seems like I heard once that the salts wouldn't work properly in stainless. Any truth to that? Thanks in advance.

I used stainless tanks for everything but the bluing tank. Here is what Brownells has to say about their stainless tank.

"""Ideal for cleaning solutions, boiling water, cold or hot rinse tanks, oil tanks…but DON'T USE IT FOR BLUING SALTS!! Bluing Salts in the presence of stainless steel and gun steel frequently can create "galvanic" action (electric current flow) between the two dissimilar metals resulting in a "false plate" of either chemicals (streaking the bluing with random iridescent blues/greens/purples) or stainless steel (giving patches of random silver specks/spots). So - use for all other tanks to prevent rusting and mess; but keep your bluing salts contented and bluing right in our Black Iron Bluing Tanks!!""""

Ramrod is correct. I once knew a gun tinkerer who insisted on stainless for his bluing bath and his work always had iridescent swirls of green and other colors.

Yes, it leaches the chrome out of the tank walls and that is bad.

Dulite makes salts designed to be used in stainless tanks. They even sell full kits. Check out their website, you can download the directions. I have one of there 4 tank ss kits I picked up. One of these days I need to order some salts. But have been researching them as I thought the same until I read their literature.
Here is a link to the kit I have. http://www.du-lite.com/dulite_gunsmith_GST202.html
Don

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I used stainless tanks for everything but the bluing tank.

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I used stainless tanks for everything but the bluing tank.

I bought the tanks 25 years ago from a smith that blued in the stainless tanks, don't recall anybody complaining. I didn't use it that way... I had a tank made up of iron that is wider and I don't have to crowd parts when bluing.