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Jewelry construction cont'd -- finishing


#1

Thanks for all your suggestions about attaching the pearls to
the brooch. Consensus is to solder post to piece, epoxy the
pearl to that and then epoxy another wire with balled end through
other side of pearl.

My next question, and I guess this applies to gold work in
general, is how to finish the piece. Specifically, through all
the firings of the piece, the gold color has changed from a warm
buttery color to a lighter, greenish (perhaps) hue which is
probably due to pure gold on the surface.

My equipment – a Smith setup and a flexshaft with different
polishing mandrels.

What do you recommend to get it back to the traditional gold
color. And also, how can I avoid polishing down details.

Thanks in advance.

rd


#2

What do you recommend to get it back to the traditional gold
color. And also, how can I avoid polishing down detai >>

We would prepolish it with small brushes at our bench (3/4
inch). Soft brushes in easy to reach and flat areas and stiff
brushes in hard to reach areas, Stiff brushes can leave grooves
if you aren’t careful. You would probably charge the brushes with
brown tripoli. The color change is just on the surface. You can
really direct where you want to polish with little brushes, and
if careful won’t polish any detail away. You could switch to
rouge and small brushes but usually people will go to their
polishing machine for the final. You won’t want to do any
polishing after you glue the pearls on, this may do many bad
things (make your glue turn white or show, damage pearls, pull
one off sending it directly into you eye, etc).

Mark Parkinson


#3

The greenish color is due to the copper near the surface being
oxidized during soldering and then being removed by pickling
operations thus leaving a high silver content gold alloy near the
surface (the silver is unaffected by the pickle). Polishing will
remove it. A weak nitric pickle may remove it.

Jewellers also use a number of ways of enriching the pure gold
at the surface (see the paper on depletion gilding on the Tips
page at Ganoksin for lots more). Some of the methods involve
cyanides and are rather dangerous and unpleasant. I sometimes take
a finished piece (no stones set) and place it cold into a
container with 1:3 HCl cold and leave it for a hour or so to
enrich the surface. Charles

Brain Press
Box 1624, Ste M, Calgary, Alberta, T2P 2L7, Canada
Tel: 403-263-3955 Fax: 403-283-9053 Email: @Charles_Lewton-Brain

Metals info download web site: http://www.ganoksin.com/borisat/tip_sear.htm
Product descriptions: http://www.ganoksin.com/kosana/brain/brain.htm
Links list hosted at the Metal Web News:
http://tbr.state.tn.us/~wgray/jewelry/jewelry-link.html


#4

…What do you recommend to get it back to the traditional gold
color. And also, how can I avoid polishing down details.

While buffs may work quicker, if you have detail you don’t want to
compromise, brushes will remove less metal, while getting into places
that buffs may not reach as effectively. Remember to keep brushes
charged with compound. If they are run “dry” they very quickly wear
out. Something I learned the hard way, until a friend clued me in.

Good luck.

Sharon Ziemek


#5

RD, Do you have a rectifier? If so, something you may want to try is
the non-cyanide based electropolish and stripping solution. I use it
on all my castings before final polish and after I have done alot of
soldering on a piece that has become “pinked”. It works very well. I
think most tool suppliers sell it (although its a little pricey -
about $175.00). It comes in a kit with everything you need to
electrostrip and electropolish. It has saved me countless hours on
finishing time. If you can stand the smell (rotten eggs) you may want
to give it a try. If not, you can use the old method of a sodium or
potassium cyanide soak - although I have as just as good of results
with the non- cyanide formulas and they are Much safer. Ken