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,