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Old 23rd Jan 2020, 11:37 pm   #23
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 3,527
Default Re: Black oxide coating on brass

When I used to do my own black and white photography, I found that spillage of exhausted fixer would silver plate the pennies I used to use under the fixer dishes to level them up. The plating was initially black, but would readily buff up shiny using a cloth. I found it worked on the brass door knobs of our prefects' room. If
left the silver plating would soon blacken. Finding someone who still uses traditional processing that used fixer could be cadged from might be less difficult than trying to source toxic chemicals. The fixer should ideally be as exhausted as possible: fresh fixer contains no silver.
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