Fine gold colouring on lower carats

Jewelry Discussion
1

A warning to orchidians using the chemicle method of Potassium
Nitrate/Alum/Salt,

Firstly this must be done in a fume cabinet as the fumes are toxic,
second the best colouring is achieved when the article is secured on
copper wire and suspended in the froth of the boiling liquid
mixture, removing every 30 seconds and washing until the correct fine
gold colour is achieved, another tip is if you require two different
colours of gold, say a pale yellow coloured 18ct against the fine
gold background, the section that you want to leave pale yellow can
be masked out with powdered plaster mixed with a standard fish glue,
this will set hard and mask out the area needed to be left pale
yellow, and when the colouring is completed the masking will soak off
if left for a while in water, this is a method I used in the past
making 18ct gold English Field Marshal’s Batons.

James Miller FIPG.
England
@James_Miller

2

Could someone please elaborate the Pottassium Nitrate/Alum/Salt
method. Am I correct when I understand that it is a surface
depletion process?.

Thanks & Regards,
Nilesh Gupta

3

Hi Nilesh,

    Could someone please elaborate the Pottassium
Nitrate/Alum/Salt method. Am  I correct when I understand that it
is a surface depletion process?.

In 1989/90 I did an extensive research project compiling lists of
different approaches to depletion gilding, which is published here
at the Ganoksin project:

This is one of the many approaches that goldsmiths have used to
enrich the surface (and even refine) gold alloys. Varying mixtures
of these three chemicals are widespread worldwide among goldsmiths
for this purpose.

best
charles

4

nilesh, here are two threads from the archives with very informative
input from niels of bornholm, charles of calgary, kevin of uk and
john of nz

Coloring 18k gold

Depletion gilding leaving brown stain on 18k

best,
bill