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Coloring of 22K gold


#1

Has anyone sucessfully colored 22k gold without the use of Liver
of Sulphur? Perhaps by flame coloring or the use of some other
chemical? A friend had seen a piece of jewelry(22k) that had a
patina on it that was very interesting and she would like to
attempt to color some of her own work in a similar manner. The
only sure thing is that it wasnt done with Liver of Sulphur.
Michael


#2

Hi there I will tell you of an incident that happened to me.

I made an 18ct/ diamond belly button ball closure ring for a
solicitor (lawyer). Cleaned it the usual way (ultrasonic). Sent
it down to the body

piercer ready for the client. The Piercer Auto claved the ring
in a steri le bag. When the ring came out ,it had turned purple.
All hell broke loose. I really did not feel that it should be
used for the clients piercing as I did not know what had
happened. The very next day I took the ring to the Sheffield
Assay office. They ran some tests for me (that should of cost
upward of A31000).

The Assay told me that it was top quality 18ct with negligable
cadmium ( less than background). The auto-clave works at about 130
degrees C. To this day I do not know ho w it happened. Maybe some
finger grease my have reacted with the gold and oxidised it. The
purple surface just wiped off after I had it tested. When I have
the time I intend to experiment with the colouring of gold as

the colour was so vibrant. If anyone else has experienced this or
has any info please let me know.

thanks
BrianS


#3

Brian,

My main line is a line of body piercing jewelry, and I have had
some similar problems. Many piercers use povidone iodine,
chlorine bleach, or commercially prepared solutions such as
Madacide here in the U.S. These of course will discolor gold,
even 18k and 22k cadmium-free. (Although some of the colors are
interesting, few of the piercer’s clients will be happy to see
them on their beautiful gold piece.) Recommend to the piercer
that when autoclaving gold, use none of these solutions. Even
trace amounts on other items in the autoclave will discolor the
gold. Although, as you discovered, the discoloration is easily
removed. Hope this helps. Metalsmth


#4

Brian,

My main line is a line of body piercing jewelry, and I have had
some similar problems. Many piercers use povidone iodine,
chlorine bleach, or commercially prepared solutions such as
Madacide here in the U.S. These of course will discolor gold,
even 18k and 22k cadmium-free. (Although some of the colors are
interesting, few of the piercer’s clients will be happy to see
them on their beautiful gold piece.) Recommend to the piercer
that when autoclaving gold, use none of these solutions. Even
trace amounts on other items in the autoclave will discolor the
gold. Let the piercer know that other things, like the chlorine
in a swimming pool or the bleach in the laundry will also
discolor the gold. Although, as you discovered, the
discoloration is easily removed. May help keep the customers calm
about it, too. Hope this helps. Metalsmth


#5
   The auto-clave works at about 130 degrees C.  When I have
the time I intend to experiment with the colouring of gold as
the colour was so vibrant. If anyone else has experienced this
or has any info please let me know. 

G’day Brian: I was very interested in your note, and although
I am unable to comment upon the interesting purple colour, I
would mention that a temperature of 130C for autoclaving seems a
wee bit on the high side, though not much. I have done quite a
bit of bacteriological work and we were recommended to use the
autoclave at 121C for not less than 20 minutes on each item. I
used a good pressure-cooker and adjusted the weight to give a
temperature of 121C, but I always included a tiny sealed tube of
benzoic acid which melts at exactly 121C, so after one opened the
pressure cooker one could at once see whether the proper
temperature had been achieved. I would absolutely guarantee
that there are no bacteria that can withstand such a regime.
This of course, means that you could do your own autoclaving with
a pressure cooker if you wished; it is very simple. The
important thing about autoclaving is that it is the high
temperature steam which does the job. Putting the work into an
oven does not have the same effect, and the oven temperature
would need to be much higher and the work in for longer to
achieve guranteed sterility. Thank you for your note. One lives
to learn! Cheers, – /\ / / John Burgess, / / / //\
@John_Burgess2 / / \ \ / (___) \ (_________)


#6

hi brian,

you are saying the piece you made was in a dry environment? was
the sterile bag immersed in water? i’ve not seen an autaclave at
work and only know that it is supposed to sterilize things.

well, here is another foggy recollection that may or may not
help: i seem to remember when i thought i was invincible and
could do no wrong, i started to heat up a piece of 18k that was
highly polished without any boric acid mixture to protect the
surface from oxydation. the gold turned to the purple you
describe in the beginneng phase of soldering. this occured when
i initially put the torch to the piece. i don’t recall what
happened after, probably deeper oxydation.

see if you can duplicate this and there is your answer. heat
slowly and observe the color. again, this is an old experience
so don’t rely on my word.

best regards,
geo fox