Back to Ganoksin | FAQ | Contact

Casting platinum into 18k (update)


#1

I’d first like to thank everyone who respnded to my post on
casting platinum pieces into 18k gold. It works very well.

The two wedding bands came back from the caster on Monday. Since
I had built up the surface of the waxes with soft dental wax,
there was more than the usual clean up. I decided to remove part
of the surface by taking very shallow cuts in my lathe- this gave
me a very accurate thickness- and then hand filing the profile
back into the rings. The major problem was porosity in the gold
surface- that was solved with a bent bur hammer in the flex
shaft, and repeated resanding with a sanding stick. I played with
surface finishes for a while- the contrast is surprisingly subtle
between the 2 alloys- and gave the bands a soft matt finish.

Rick
Richard D. Hamilton

Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com
@rick_hamilton


#2

<< casting platinum pieces into 18k gold. >>

Rick, On a related topic. What are you having your platinum
alloyed with? Its seems most casters are using ruthenium (sp) or
cobalt. I had a discussion with a couple of freinds who are
goldsmiths and they said that I should go back to 90% platinum
and 10% irridium, that it polishes much easier. They said the
reason that many are using the others is that the irridium and
its percentage of usage (10%) is unacceptable in Japan. That many
of the large cleints of the casting houses are doing
international business and are sensitive to that. But in the US
it doesn’t affect the sale one way or another. I am going to go
back and see for myself. What do you think? Mark P.


#3

The pieces that I made used 10% iridium platinum wire from
Hoover and Strong. The wire was formed into wave shapes and
soldered with 1700 platinum solder (with my new dididium
glasses!). I haven’t used the new cobalt alloy to my knowledge.

Rick
Richard D. Hamilton

Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com
@rick_hamilton


#4
They said the reason that many are using the others is that
the irridium and its percentage of usage (10%) is unacceptable
in Japan. 

Why is it unacceptable? Penny


#5

The pieces that I made used 10% iridium platinum wire from
Hoover and Strong. The wire was formed into wave shapes and
soldered with 1700 platinum solder (with my new dididium
glasses!). I haven’t used the new cobalt alloy to my knowledge.

I was under the impression that most cast pieces in platinum are
alloyed using cobalt. Thought it improved the castibility (if
that’s a word) of the platinum. Maybe our resident PGI technical
ed. manager can give us some info, if he’s lurking…Jurgen???are
you there?

Sharon


#6
 irridium and its percentage of usage (10%) is unacceptable in
Japan. Why is it unacceptable? 

My freinds said its mainly the fact that its only 90% platinum.
For us in the states its not a factor and apparently the
percentage of usage of the other alloys is less than 10%. I
really need to check into this, I am operating on info from
friends (but fairly knowledgable friends). Mark P.


#7
  The pieces that I made used 10% iridium platinum wire from
Hoover and Strong. The wire was formed into wave shapes and
soldered with 1700 platinum solder (with my new dididium
glasses!). I haven't used the new cobalt alloy to my
knowledge.

hi rick, i’ve been using a #5 welding lens (yes i know, it should
be a #6) over my script lenses when brazing platinum. i would
love to be able to add magnification as well. would your new
dididium glasses help? what are they, i’ver never heard of them?

thanks,

geo fox


#8
   I was under the impression that most cast pieces in
platinum are alloyed using cobalt.  Thought it improved the
castibility (if that's a word) of the platinum. Maybe our
resident PGI technical ed. manager can give us some info, if
he's lurking...Jurgen???are you there?

hi sharon and rick, yu would know if you’ve encountered cobalt
alloy platinum because it oxidises, unlike other platinum
alloys. it is also great to play with the minds of your clients.
you can tell them it’s not platinum because it is attracted to
magnets. jurgen is definitely more qualified to answer your
question than i, but i can’t resist. cobalt/platinum is a great
casting alloy in 90 or 95% purity. it is popular in europe but
not here in the states. it is not reccommended for fabrication.
cobalt/platinum alloys are better to cast with than iridium or
other platinum alloys. i think the reason that it is not readily
available is because one needs to alloy the cobalt and platinum
in a vacuum type crucible not readily available in the u.s.
(according to david fell)

best regards,

geo fox


#9
They said the reason that many are using the others is that
the irridium and its percentage of usage (10%) is unacceptable
in Japan. 

Why is it unacceptable? Penny

Hi Penny,

The international standard for Platinum purity is 950 parts per
thousand or better, with the exception being findings and chain
product, where 800/1000 to 850/1000 is accepted. In the USA there
is an alloy that contains 900 parts Platinum 100 parts Iridium.
This alloy is a very good one, it is used for all applications
of jewelry making, incl casting, forging, fabricating and other
manufacturing . It can, however,not be exported into other
countries, as the Platinum content is not over 950/1000. The most
popular alloys fitting the international bill are Pt950:
950/1000 Platinum, 50/1000 Ruthenium. This alloy is great for
machining wedding bands. It is usually extruded into tubing and
the rings are sliced off and then machined on a lathe or a “swiss
machine”. Pt950: 950/1000 Platinum, 50/1000 Cobalt. This alloy is
ideal for casting. It is very wet and will fill small detail. It
is ferro-magnetic and does slightly oxidize when weldes or
soldered. Pt950: 950/1000 Platinum, 25/1000 Cobalt,25/1000
Copper. Thia alloy has been developed by Engelhard-CLAL and is
suited for casting as well as machining.

There are many different combinations of alloys out there. But
don’t let that confuse you. Just as there are hundreds of
different gold-alloys,it is the purity that counts. Platinum
Guild International USA supports high purity Platinum.

For questions regarding Platinum , please call PGI’s Hotline at
(714)760-8882 PLATINUM GUILD INTERNATIONAL USA Jurgen J. Maerz,
Manager of Technical Education JA Certified Master Jeweler


#10
    ... i would love to be able to add magnification as well.
would your new dididium glasses help? what are they, i'ver
never heard of them? 

Being over 40, I can’t see a thing without magnification. I use
the clip-on magnifiers (2.75x)on my normal glasses rather than an
optivisor and I have found that they work on the welding glasses
also.

Sharon Ziemek


#11

They are the glasses glassblowers and beadmakers wear to protect
their eyes, and are comfortable to wear under an optiviser. I
asked a beadmaker where to get them- they were $140 but the next
jobs went a lot better for having them.

Rick
Richard D. Hamilton

Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography

http://www.rick-hamilton.com
@rick_hamilton


#12
   Being over 40, I can't see a thing without magnification. 
I use the clip-on magnifiers (2.75x)on my normal glasses rather
than an optivisor and I have found that they work on the
welding glasses also.

thanks sharon, i’d forgotten about those. do you have a
particular type that don’t scratch the scripts? this comes from
fellow over 40.

best regards,

geo fox


#13

thanks sharon, i’d forgotten about those. do you have a
particular type that don’t scratch the scripts? this comes from
fellow over 40.

George, I use the Peer magnifiers which do come with little
rubber protectors on the clip, which do wear through very
quickly. The scratched area on my lenses is close enough to the
nose that I don’t notice it. I do occassionally use a polishing
compound for watch crystals (Crystal-Kleer from Grobet) to polish
the scratches that I get on the magnifiers.

I found them in the Frei & Borel catalog (Catalog GHD93R - the
blue book). Hope this helps.

Sharon Ziemek