Gun blue composition


Birchwood Casey seem to have changed the compositon of their Super Blue
Liquid Gun Blue. I have recently bought the bottled version and the paste
version. Both are labelled as containing Selenium dioxide. The paste version
works really nicely on steel (in fact I think the coverage is less patchy)
but will not touch brass (as indeed the label now clearly states).
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10 years ago (I still got the bottle to prove it) the liquid version
contained "nitric, phosphoric and selenious acid" and blackened brass really
nicely.
Is there a reason why the company changed the composition?
Furthermore, does anyone have experience with the Brass Black Metal Touch up
(15225 -BB2)?
Is it any good at turning brass black? Is it similar to Gravoxide?
Thanks,
Reply to
Michael Koblic
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Michael, You are speaking about a cold blueing compound which is acidic. Proper gun blueing compond is a base(salt) and it is mixed with water and heated to aproximately 295F. The amount of salt is conntrolled by observing the boiling point of the solution. Steve
Reply to
Steve Lusardi

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