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Torch fuel 4 Platinum


#1

First of all, many thanks to all of you out there for all the
great you’ve given me over the past year or so. This
really is an incredible resource!

Next, the first of two questions. (I’ll send the other in
another message so we can keep the threads seperate.): I’m a
dedicated hobbiest, and so far I’ve worked in 22K gold and fine
silver (Greek/Roman/Etruscan-style chains and granulation) and
I’d like to try experimenting with platinum. So far, I’ve always
used a Smith acetylene/air torch, which has been fine for silver
and gold work. I’ve always heard that, in order to work in
platinum, you have to use some sort of fuel/oxygen mix for a
torch. Looking in various resouces, I see that the highest
temperature that you can get with acetylene/air mixture is 4217
degF, and the melting point of pure platinum is 3224 degF and
platinum/iridium 990 alloy melts at about 3250 degF.

My question is: why do you need to use an oxygen/fuel mixture if
you can get almost 1000 degrees above the melting point with
acetylene/air? Can you only get that hot of a flame by mixing
COMPRESSED air with the acetylene? If I DO need to go to a
fuel/oxygen mix, I’ve read that oxy-acetylene produces too dirty
of a flame for platinum work, so what fuel do you platinum
people out there use?

Also, I’ve read that platinum is easily contaminated. Do I
simply need a seperate soldering pad, or do I really need to get
serious about keeping platinum away from other materials?

Thanks in advance,
Alan

P.S. I think part of the reason that I’m drawn to platinum is
from watching “Lost in Space” as a kid. It seemed like every
other week, Dr. Smith would find some huge amuont of
"PLAT-i-num!!!"

Alan Derr
Senior Applications Consultant
Summa Four

phone/fax: (603) 665-3138
pager: (888) 712-5430

Cisco Systems, Inc.
25 Sundial Avenue
Manchester, NH 03103 USA


#2

We use an oxy acetylene mix for everything we do and we do lots
of platinum work. Haven’t had any problems with it. I’m sure
Kurt and the others on the list here will answer the rest of your
questions.


#3
 My question is: why do you need to use an oxygen/fuel mixture
if you can get almost 1000 degrees above the melting point with
acetylene/air? 

As you heat a piece of metal, it radiates that energy back out
again. Brightly glowing platinum is radiating energy rather
quickly. You need to be pumping the BTUs into the metal faster
than it can radiate them back out again. Air acetylene is a
gentle, soft flame. the actual max flame temp in a small region
may be hotter than the melting point of platinum, but only in a
small area, and actually getting solder to flow with that flame
will be almost impossible. an analogy: The flame temp of a
candle flame exceeds the melting point of silver solder. Try
soldering the shank on a silver ring with a candle flame… If
you had a really big candle, and could totally immerse the silver
in that hot portion of the flame, it might be possible. but in
practice? Not likely. With platinum, even with an oxygen/propane
torch, a fiercly hot flame, you often have to work hard to melt
the platinum. It radiates heat so quickly that it takes a good
deal of “overkill” to melt the stuff with any efficiency. And
in working platinum, as with other metals, often we wish to
isolate the heat to only the portion where we wish the solder to
flow, while other portions stay cooler, perhaps to protect
stones, or prevent the flow of previous solder joints. You need
a sharp, hot flame to do that. Air acetylene just isn’t.

and another comment. Working with platinum, it’s essential to
prevent absorbtion of carbon into the platinum or platinum
solders, since carbon will cause brittleness. Any acetylene
flame, whether air acetylene or with oxygen, will have some
excess carbon in the flame. The air acetylene flames are gentle
and reducing because of this excess carbon, making them
wonderful for silver work. But it makes the completely unsuited
to working platinum, especially since you cannot adjust the gas
mix to get an actually oxidizing flame. With platinum, almost
all work is done with sharp oxidizing flames, to prevent this
problem with carbon absorbtion. Although natural gas and
propane are also hydrocarbon fuels, their flames have less free
carbon it them, makeing them safer. Although oxy/acetylene is
hot enough to easily work with platinum, it’s risky, again due to
the availability of at least some free carbon in the flame,
unless it’s a really sharply oxidizing one. The safest in this
regard, is hydrogen fuel, which of course has not carbon. But
hydrogen/oxygen flames can be a little harder to use, being hard
to see, among other things. It should be pointed out too, that
oxyacetylene isn’t completely safe for use with golds either,
especially with casting operations. Some alloys will tend to
form carbides when melted with available carbon (can also come
from crucibles), which can evidence themselves as harder
includsions within the parent metal of the casting. These can
make a casting very difficult to finish well. Unlike gas or
shrinkage porosity, carbide inclusions cannot be so easily just
burnished out of the surface, and even if you go to measures like
using diamond compounds to polish the surface (which does work,
if you need to do this) the carbide inclusions will still show up
as color differences…

Peter Rowe


#4

Alan you are correct in that your tourch is hot enough for
soldering/welding but acetylene would be that last gas to use for
Platinum fabrication. The best gas would be hydrogen/oxygen the
next gas combonation would be propane/oxygen, then butane,
natural gas then the last on the list would be acetylene. This
is based on the risk of carbon pick-up. Acetylene can be used but
with excess oxygen to create a very oxidising flame. If you are
only soldering I would say that you would have no problem with
your setup, but you would need to use an oxidizing flame.

As an example if you were going to cast an ounce of platinum,
you need to melt it in about 12 to 30 seconds to avoid exessive
carbon pick up. Your torch will eventually melt the metal but it
will take 30 minutes to do so. In order to achive such a fast
melt your torch has to be several 1000 degrees above the melting
point and this can only be achived by compressed systems. I use
65 lbs. oxygen and 5 lbs of propane to achive tempretures hot
enough to melt the platinum in 12 seconds to do my casting.
Platinum solidifies in 3 seconds after the heat is removed so
speed is crucial to get a complete casting.

   Also, I've read that platinum is easily contaminated. Do I
simply need a seperate soldering pad, or do I really need to
get serious about keeping platinum away from other materials? 

You should only use appropriate blocks for platinum soldering,
fused alumina holds up the best and takes tremendous amounts of
heat. Charcoal is carbon and will contaminate the metal. Use
the fused block only for Platinum work. Platinum does not get
contaminated as easily as reported but one must work cleanly to
avoid the contamination. Common sense should be used. Separate
bench or hand tools are over kill, but you should use a separate
soldering fused block, separate polishing buffs. Store in
plastic bag after use to avoid contamination. If you do
polishing at the bench some of the iron oxide can get onto the
soldering block then transfer to the metal. I recommend the use
of tungsten carbide spring tweezers to hold platinum while
soldering this metal is the only metal that we use that can take
the heat. Clean you files before use on platinum or just use a
set for it, I just clean mine.

Always wipe the rolls of you rolling mill before using it for
platinum and if drawing wire use a tungsten carbide drawplate,
these plates have polished holes and leave the drawn wire highly
polished. Do not use wax to lubricate the wire and use only for
platinum to avoid contamination. before annealing always place
the item into the pickle or a warm 10 percent nitric bath to
remove any trace of steel from the platinum. As I have said
before you must heat the platinum to brite-orange for 1 minute
per 1 millimeter thickness to ensure full annealing.

While soldering it is very important to remember to never use
flux with solders 1300 degrees and above or the seam will become
brittle due to flux contamination. Do not use binding wire
unless it is platinum. At the bright-orange color of heated
platinum it is hot enough to melt gold, silver or any other metal
which would then fuse onto the platinum. Silver contamination
will cause a lot of trouble with platinum.

Your best bet is to contact the Platinum Guild and ask Jurgen to
send you some of the handouts they supply to the trade. You can
also go to the Platinum web page pgi-platinum-tech.com and view
the technical books and sources there. AJM magazine is a great
resource to the trade it is filled with technical
You can go to their web site mjsa.plygon.net/ajm/. Gesswien has
a lot of these items and Elaine Corwin whom is online here, she
can send you some on supplies. I do not know their
web page link.

There is a whole lot of to gather I hope this will
help a little.

Edward J. Friedman
Senior Instructor The Revere Academy
Consultant


#5

Acetylene will expell carbon and thus contaminate platinum. The
choices for working with Platinum are Hydrogen/Oxygen or propane
/Oxygen. For small construction work you may even use Natural gas
/Oxygen mix. Be sure you use an oxidizing flame and protect your
eyes with at least a #5 safety goggle for fabrication and a
#11-12 for casting.

For more visit our technical web site at
http://www.pgi-platinum-tech.com or call me at 949 760-8279
Have a platinum 1999
PLATINUM GUILD INTERNATIONAL USA
Jurgen J. Maerz
Mgr of Tech.Education
JA Certified Master Bench Jeweler


#6

Edward,

Thank you very much for your response. I think it answers the
two main questions I had (without raising TOO many others!). I
think I’ll go for the propane/oxygen setup, since I can get one
of those at a relatively low price to try out. If it turns out
that I love working in platinum, maybe eventually I can spring
for a hydrogen/oxygen torch. I’ll also get a fused alumina
soldering pad.

You should only use appropriate blocks for platinum soldering,
fused alumina holds up the best and takes tremendous amounts of
heat. Charcoal is carbon and will contaminate the metal. Use
the fused block only for Platinum work.

This makes a lot of sense. I probably wouldn’t have thought
about the charcoal contaminating the platinum until it was too
late (or the charcoal block burst into flames!)

I have a tungsten carbide drawplate, but one part of your
response I didn’t quite follow:

Do not use wax to lubricate the wire and use only for
platinum to avoid contamination.

What DO you use for lubrication? Do you mean only use the
drawplate for platinum?

Your best bet is to contact the Platinum Guild and ask Jurgen to
send you some of the handouts they supply to the trade. You can
also go to the Platinum web page pgi-platinum-tech.com and view
the technical books and sources there. AJM magazine is a great
resource to the trade it is filled with technical
You can go to their web site mjsa.plygon.net/ajm/. Gesswien has
a lot of these items and Elaine Corwin whom is online here, she
can send you some on supplies. I do not know their
web page link.

Thanks for all the info. I can’t wait to get started!

Happy New Year,
Alan

Alan Derr
Senior Applications Consultant
Summa Four, Enhanced Services Migration Business Unit (ESMBU)

Cisco Systems, Inc.
25 Sundial Avenue
Manchester, NH 03103 USA

Direct: 603-665-3138
Fax: 603-695-1243
Pager: 888-712-5430
@Alan_Derr


#7
   What DO you use for lubrication? Do you mean only use the
drawplate for platinum? 

Alan,

This type of drawplate has very highly polished holes and the
jump in size is a lot smaller. the holes being polished in
conjunction with the smaller jumps in hole size, the wire passes
through the holes easily. If I need to use a lubricant I will use
oil of wintergreen. it tends to lubricate well and does not leave
a film that is hard to remove. after drawing the wire prior to
annealing it goes into the pickle and the oil is removed then.

I have been casting Platinum with propane in a horizontal
centrifugal for about 5 years now and feel no need to change to
Hydrogen.

Edward


#8

Edward and others, can I successfully cast platinum in a Ney
centrifuge? Thanks, Peter Slone


#9

Edward, Ivory soap is a perfect lubricant for platinum work. If
oil of wintergreen gets into an eye or a cut, it is killer. Have
a good day. Tom Arnold


#10

Edward and others, can I successfully cast platinum in a Ney
centrifuge?

Peter,

At The Revere Academy I teach casting with the Ney centrifugal
machine and the vertical machine. I personally own the Ney and
cast at least 4 to six ounces a month for the trade on this
machine with wonderful results. I find that with this small
volume there is no need to purchase the vertical machine.

To use the Ney machine and all you have to do is buy a GAAB
crucible converter from Rio Grande. I holds a large type A
crucible. It will run about $80.00 with a crucible. You have to
place the weight in the medium hole to add a little extra
volocity. Do remember to use eye protection of at least #11
lenses. I use a standard flip up welding goggle that you can get
at any welding supply store. I place a #5 lens in the body and
a #6 lens in the flip up. This makes it so I can see everything
with the #5 and as I heat the metal up I flip the #6 down as the
metal begins to heat up and I need more protection.

Now you have to choose an investment for casting and you will be
set. I have used about every investment on the market and for our
class we use five different brands of investment. There are many
on the market and it will depend on time frame and surface
texture you desire.

The cheaper investments leave a grainy surface but setup time
can be from 1 hour to 6 hours depending on the brand, the more
expensive investments take abut 12 to 16 hours to setup but the
surface finish is as smooth as a baby’s butt. Supra investment
by far gives the smoothest surface with a setup time of about 14
to 16 hours. Platinite II sets up in around 5 to 6 hours with a
slightly grainy surface texture.

Elaine Corwin did an article for AJM Magazine in the August
issue in which she gives a lot of about the whole
process from equipment, investments, spueing, investing and
everything related to this question. There is also an article
just about Evaluating Investment by the former Platinum Technical
advisor Chris Cart. A very good issue and well worth reading
http://www.mjsa.ploygon.net/mjsa

Elaine Corwin	VP Tech Services	GESSWEIN CO INC USA
Bridgeport CT 06605	Phone: 1-800-544-2043, x287
Fax: 203-335-0300	Email: gessweinco@aol.com Direct Email: ElaineEC@aol.com

I use a fast setting investment that sets up in 15 minutes and
can cast one flask within two hours of setup of the investment.
You can use it on gold and silver and in a pinch I can cast a
Platinum ring in the morning and have the job polished and set by
the end of the day. If you want more info www.jewlerschoice.net
or you can call Marvin Schmidt at 800-862-9362 and he can give
you more detailed about his product.

I hope this helps and good luck
Metal Regards Edward


#11

Yes, you can successfully cast platinum in a Ney centrifuge. We
do it all the time.

Alan Revere