Dilute Black Oxide Solution

[Chet]

What is the shelf life of diluted Balck Oxide solution at 70 deg. F?

What precautions can I take to prolong shelf life?

Chet

[mcaswell]

There's no known shelf life on this product.

Make sure the container is plastic or glass, is sealed tightly and marked with its contents.

[Chet]

After about six months of no usage I took down my Black Oxide solutions and found that a white salt collected in the bottom of the "Black Oxide Solution". It dissolved when I shook the solution and parts seemed to color to dark, but not as black a color as in the past.

In the past I have coated many small parts, all resulting in a rich dark black color. The newly coated parts were made from 12L14 Steel, containing more lead for ease of machining.

Is the 12L14 steel the problem with the depth of color or do I have a problem with the old solutions?

Chet

[Fibergeek]

No.
I have experience with finishing 12L14 with most chemical conversion methods, from hot caustic blueing to cold blue and black oxide. I haven't tried Caswell's, but I have no reason to believe it would be any different. This alloy is quite easy to finish, it took every finish, including Parkerizing with no difficulties. The miniscule lead content of 12L14 has no effect on the finishing.