PLATINUM 101, PART II:
SAFETY, REPAIRS AND FINISHING
by Jurgen J. Maerz, Platinum Guild International-USA
As you know, extremely high temperatures are used to work on platinum.
This releases ultraviolet radiation, which along with the bright light created
by the welding or brazing process, is harmful to the eyes. So No. 5- or
No. 6-rated safety goggles are a must.
When sizing a platinum ring, welding is the method of choice. With platinum/cobalt
alloy, however, the 1700 soldering method is preferred. There's no problem
welding like platinum alloys together, but alloys of different composition
can't be welded together as they have different melting points. For example,
Pt/Ir can't be welded to Pt/Ru. However, Pt/Ru to Pt/Ru poses no problem.
Many fine pieces of jewelry are being manufactured using platinum and
18k gold. A piece of that metal combination requires gold technique for
repairs. Platinum techniques would ruin the piece because the higher temperatures
required are too high above the melting point of the gold.
Finishing platinum requires a special technique. Usually after the sandpaper
finish of 600 grit, the polishing phase begins. A gray compound of 800 grit
is followed by a white compound of 1,500 grit, which is then advanced to
a prepolish with a 4,000 grit, to be finalized with a luster that a carrot
or green rouge will create at about an 8,000 grit.
Slight surface irregularities and porosity can be removed with a tungsten
burnisher before the final stage. It's important that a polishing wheel
is dedicated to an individual compound and there's no cross-contamination
among wheels. The jewelry and the hands must be cleaned between steps. When
polishing bimetal pieces, the platinum portion should be finished first,
as it takes more steps to polish. Polishing gold next to platinum in one
operation will lead to the over-polishing of the gold portion.
Jurgen J. Maerz is manager of technical education for Platinum Guild
International-USA. He can answer your technical questions 24 hours a day
at PGI's platinum Hotline, (714) 760-8882. He was the fourth in the U.S.
to earn the Jewelers of America certification as JA Certified Master Bench
Jeweler. Copyright © 1998 by Bond Communications.