This is my fist post so I'd like to take a moment and extend a thank
you to everyone who has shared their knowlegde freely and
unrestrained. I think it is fantastic. I hope I will be able to offer
some assistance in the future.
I am asking a question for our jewellery departmetn at NSCAD because
we are stumped.
Along with many other techniques we teach solder/metal inlay. I
number of students have expressed an interest in blackening copper
pieces with silver solder inlay so that the copper is a rich black
and the silver solder a bright white.
Here is what I know/have tried:
I know that liver of sulphur, the Jax blackening solutions and
Rokusho all create great patinas but all of them either colour the
solder or are not black on copper.
I have been searching out the proper recipie for Korean "Black C"
I have tried Mr. Lewton-Brain's (18%sodium hydroxide solution 18g
sodium hydroxide and 100cc distilled water) to no avail and I have
also tracked down with the aid of our faculty member Kye-Yeon Son,
the author of a Korean patina book which listst the recipie as 5:1
sodium hydroxide to sodium chloride. But there is no indication of
concentration of the sodium hydroxide. When we contacted the author
he said that he had gotten the recipie from industry in Korea (where
Black C can be bought pre mixed) and does not know the concentration.
I've tried heating solutions and dipping, heating pieces and
dipping or both. I have managed to get some pretty cool colours but
not what we have been looking for. I am hesitant to mix up any more
chemical as it is not my favorite thing to do, especially when I am
responsible for the students around me.
I am wondering if the key has to do with the zinc in silver solder,
that is probably what is turning colour (usually the silver solder
Does anyone have any suggestions?