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Platinum issues


#1
 I have been using oxyacetylene with a "Little torch" all my
jewelry life.  Early on I added a flux tank to the acetylene
line"... 

Query from Tom Kruskal about fuel for platinum soldering.

Acetylene is not recommended for platinum soldering because platinum
is easily contaminated by carbon and acetylene is a carbon rich gas
producing a very sooty flame until mixed with oxygen. Generally
speaking, keep all forms of carbon away from platinum, especially when
soldering at high temperatures. Do not, for example, use the charcoal
block to solder on.

Platinum does not oxidize so you can get away with acetylene by using
an excess of oxygen in the mix, producing the oxidizing flame that you
want to avoid when soldering silver or copper.

You can use the oxy-hydrogen set up that you indicate, but you have to
be careful with the hydrogen, especially indoors. There is a certain
risk there. Check with your gas supplier for details.

I have been using oxy-propane successfully with the Little torch using
the number 6 tip and feel that this is perfectly adequate for rings
and pendant sized objects. Personally I like to keep things as simple
as possible, and if it works don’t fix it.

Alan Revere has a chapter on platinum in his “Professional
Goldsmithing” book.

For more contact Jurgen Maerz at Platinum Guild
International: jmaerz@earthlink.net.

Riccardo Accurso
Ricco Gallery of Contemporary Art Jewelry
125 W German St /PO Box 883
Shepherdstown, WV 25443-0883


#2
Platinum does not oxidize so you can get away with acetylene by
using an excess of oxygen in the mix, producing the oxidizing flame
that you want to avoid when soldering silver or copper.  

Riccardo: Thanks for solving the mystery — I followed the thread on
platinum and acetylene back several months ago and couldn’t figure
out how the jewelers worked with platinum in the Edwardian period —
it seems to me that they were at first using acetylene because of its
high temperature, but maybe I’m wrong. At any rate you’ve provided
the explanation of how it could be done. Maybe someone else will
respond with the history of how platinum was worked when it first
came into use in England and Europe (circa ~1880??).

Regarding using propane with the Little Torch, if I switched over
from the setup I have now with the R oxygen tank and MC acetylene
tank and a Little Torch, what would I need to change to use a 20 lb
propane tank instead? Could I switch back and forth?

Thanks,
Roy(Jess)


#3

Just buy a tank, I use an acetylene regulator for propane. Believe
me propane is plenty hot to work platinum. If you change anything or
add to the setup it would be to get a mecco midget torch this would
really expand your capabilities especially on larger pieces Robert
Benham


#4

To use acetylene/oxygen to work with platinum is not recommended.
Acetylene expells carbon within the flame, which is absorbed by the
platinum causing imbrittlement. Even within an oxidizing flame carbon
is expelled. Those of you who claim to be successful using acetylene
with no problems have been lucky…

PLATINUM GUILD INTERNATIONAL USA
Jurgen J. Maerz
Director of Technical Education
JA Certified Master Bench Jeweler
http//:www.pgi-platinum-tech.com


#5
To use acetylene/oxygen to work with platinum is not recommended.
Acetylene expells carbon within the flame, which is absorbed by the
platinum causing imbrittlement. Even within an oxidizing flame carbon
is expelled. Those of you who claim to be successful using acetylene
with no problems have been lucky...

With al due respect, Jurgen. When I was in elementary school or
thereabouts, we were taught that a yellow flame was evidence of free
carbon and carbon monoxide being released from a candle or gas flame.
This free carbon can be seen as soot. When additional oxygen is added,
the carbon particles are converted to CO2 and the lack of glowing
particulate matter results in a blue flame. I find it hard to believe
that these principles don’t apply to oxy/acetylene. I suspect that the
real problem is in keeping a clean work place. The free soot floating
around a shop could for sure result in some platinum contamination. One
more point. Some years ago, about the same time that I learned what
was making some of my platinum brittle, I also learned that bringing
platinum to a yellow or even white heat in an oxidizing atmosphere
would allow the carbon to escape. This little trick has saved me from
careless acts of stupidity in the past and I would recomend trying it
before starting a job all over.

Bruce

Bruce Holmgrain
JA Certified Master Bench Jeweler
http:\www.goldwerx.com