Enamel on platinum?

Jewelry Discussion
1

A client wants a small charm in platinum with enamel in a small
recessed area in the center. Any would be appreciated,
Lucy, my studio partner, has never enameled on platinum, but was told
it is difficult because of expansion issues.

Rick

2

Rick, you might want to ask Tom Ellis at Thompson Enamel about the
feasibility of doing an enamel on platinum. Thompson has a web
site, and you can email your question to him. You are right to be
concerned about expansion problems. Alma

3

Rick

Quote from “Thompson Enamel Workbook” page 9: "Several references
indicate platinum cannot be enamelled because it has a terrific
expansion. Actually it has a very low expansion. In general, metals
with high melting points have low expansions and metals with low
melting points have high expansions. The same is true for glass.
Glasses with high softening points generally have low expansions, and
glasses with low softening points generally have high expansions.

Both Thompson’s Medium-Temperature - Low Expansion enamels fired at
1450 deg. F and their High -Temperature - Medium Expansion enamels
fired at 1600 deg. F work well on platinum."

Link here to eNAMEL Online Newsletter feature article on U.S.
goldsmith-jeweller Gallen Benson and some of his work incorporating
cloisonne enamels on platinum.

http://users.netconnect.com.au/~enews_01/eNAMEL_vol1_no4_January_2002.html

cheers
Al Heywood

4

HI!

It won’t stick, when I make plique-'a-jour I use platinum foil for
backing the first filling of the enamel and then can just pull it
off the enamel after firing. This is the way that dental labs to
porcelain crowns. I learned this from my dentist husband. Pat
DIACCA Topp www.DIACCA.com

5

Hi Rick and Lucy,

don’t believe all you hear about enamel on platinum causing expansion
problems. I have been doing a lot of enamelling on platinum and have
had no trouble at all with coefficient of expansion. As a matter of
fact the very work I am doing on platinum is being done because
platinum is so inert under glass. There is more expansion and
contraction in the glass than there is in the platinum. I don’t know
what the so-called experts would say to this. All I know is this is
what I do and it works. (Have you ever noticed how so many more
"experts" tell you you can’t do things than tell you that you can?)

One unusual characteristic of enamelling on platinum is that the
enamel can be easily dislodged from platinum because the enamel does
not readily adhere to platinum especially if the platinum is highly
polished. I exploit this characteristic when building 'plique-a-jour
pieces. I pre-enamel smaller components on platinum shim then simply
peel the thin platinum sheet from the underside of my plique-a-jour
piece. It’s a bit like peeling foil off a toffee. I then re-enamel
all my components together for (I think) quite unusual 'plique-a-jour
effects.

To get back to your immediate task, the only suggestion I would make
is that you texture the surface of the platinum to be enamelled. This
will ensure that the enamel adheres when it is fired. Make sure any
solder joins are high melting point because your enamel will fuse
around 600 to 700 degrees centigrade.

I don’t know exactly the nature of your task, but if the platinum
charm is only small in the middle of an existing piece of jewellery,
you may be able to work with relatively thin platinum and fuse the
enamel by torch from behind. It’s just a suggestion… Kind regards,
Rex Steele Merten

6

Maybe fusing some 22k or fine gold to the platinum and enameling onto
that? The cavity that we are enameling is not very big, roughly
triangular, maybe 9x6 mm and about .75mm deep.

Rick Hamilton

7

Paladium foil is used as a substitute for platinum foil to form
porcelain crowns in the dental lab. There is no reason for it not to
work with your applications in jewelry. Porcelain is fired to the
platinum/paladium foil and it is removed after the crown is completed
by peeling it away from the procelain. Like “unwrapping toffee”.

8 
    A client wants a small charm in platinum with enamel in a
small recessed area in the center. Any would be
appreciated, Lucy, my studio partner, has never enameled on
platinum, but was told it is difficult because of expansion issues.
Rick

Rick re your comment above. There was a discussion about this topic in
the archives, so if you can, check it (them?) out.

I was mistaken at the time in believing that enameling on platinum
could not be done. Apparently it can. If I recall the enamel was used
to fill in a groove.

David