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[How2] Platinum inlays


#1

I am currently working on a wide ladies ring in 14k y.g. which
the customer requests to be inlaid with platinum in a pattern on
each side. I was told by an experienced jeweler that, because of
the difference in the rates of expansion & contraction, my
relativly thin platinum pieces would crack. Is this the case and
what is recommended to prevent this from happening?

Also, would someone out there please give me their method for
doing this? I am concerned with gaps between the pieces just
what carat/heat range of solder to use and the best method for
finishing. Many thanks in advance; Steve Klepinger


#2

Hello Steve, I don’t know at what thickness your platinum would
would crack, but it would have to be mighty thin. I’m sure that
.3mm is thick enough. Use 14ky hard solder and you’ll do fine.
Use enough solder to fill in around the platinum. The fit of your
platinum piece should be as close as possible. Have fun.
Tom Arnold


#3

Hi Steve,

I have never found cracking to be a problem in platinum inlays
even if they are thin. I would be careful not to make it too
thin, more as a wearability and finishing problem. It sounds like
something where I would try to cast the platinum sections in
place, rather than soldering. That may be much easier. You do
need to make keys for the gold to grab onto and add pins or
design your ring so you are sure the platinum pieces don’t float
around during burnout.

Do you mean the cust wants the platinum on the edge of the ring
when you say each side. Because if you are talking about a
platinum sleeve I have a good way to do that . Maybe you could
elaborate.

Mark P.
WI


#4

Steve, the best way to do this is by-metal casting. You first
fabricate the plat. pieces and polish to showroom finish. Then
sink them into a wax of the band, setting them down about . 25 mm
below the surface of the wax, thereby leaving enough for
polishing of the gold. The plat. wont polish away before the
gold and wont oxidize like gold. Then invest and cast like
normal. If that is not an option the just use a med. melt solder
and scuff the area were the bond is on the plat.,here again
polish the plat. to showroom finish, use small pieces of solder
and don’t worry if a little gets on top of the plat.,it will
polish off without hurting the plat.

good luck, Bob
Hoff Jewelers
St. Paul,Mn.


#5

Oops, Sorry Steve, I forgot to add that I don’t use solder on my
inlays - Rex.


#6

Hello Steve, If I were to do this job I’d cast the platinum
inplace, and for go the solder. True


#7

I just finished 3 bands that had fabricated platinum iridium
sections that were inserted into waxes and cast- works just fine.

Richard D. Hamilton
USA
Fabricated 14k, 18k, and platinum Jewelry
wax carving, modelmaking, jewelry photography
http://www.rick-hamilton.com


#8
   I am currently working on a wide ladies ring in 14k y.g.
which the customer requests to be inlaid with platinum in a
pattern on each side. I was told by an experienced jeweler
that, because of the difference in the rates of expansion &
contraction, my relativly thin platinum pieces would crack.  Is
this the case and what is recommended to prevent this from
happening? 

The platinum won’t crack. The solder seams are what’s at risk.
Generally, if both pieces of metal are well annealed, you won’t
have problems. Besides, if the platinum pieces are just inlays,
they’re relatively small in relation to the gold, and will simply
adjust themselves to it. Like I said, thoroughly anneal the
platinum first. Use the hardest solder you feel comfortable
with for a good color match and minimal solder seam pits.

Peter Rowe


#9

Steve, I’ve been doing platinum and 18ct gold inlays in titanium
( and vice versa) for some years now. I’ve had no trouble with
either metal cracking because of small differences in their
coefficient of expansion. As a matter of fact I find the other
jeweller’s assertion that the platinum would crack a little
startling. Platinum is one of the most forgiving metals I’ve
ever worked with (I’m talking both pure platinum and 5% Cu alloy
here).

As far as inlaying goes, I find that it’s easier to work with
the inlay metal slightly thicker than the host metal; eg. if I
was inlaying into 1.5mm gold host, I’d make my inlay around
1.8mm.

Before I inlay I file a neat chamfer on both sides of the shaped
hole in the host, then fit my inlay piece accurately into the
shape required. With a 4oz steel ball-pein hammer I work the edge
of the inlay over the chamfer and finish with the flat face of
the hammer to close the edge of the inlay tightly onto the host.
Be careful not to whack the centre of the inlay too hard, because
you could distort the shape of the ring. A ring is easy, because
you have the ring mandrel to hammer against, and that takes care
of the under side spread. I sometimes make sure of the
inner-shank spread with my flexible shaft setting hammer-tool.

When the inlay is tight against the host, finish off with a file
and emery and polish as usual.

I did a sphere of 18ct recently where I did all my inlays in
titanium while the sphere was still in its two hemispheres, and
did all my inlaying against an appropriately sized steel doming
(dapping? - you say dapping, we say doming:)) punch. That was
fun.

Hope this helps, Rex from Oz


#10

Mark:

Could you elaborate on your method of preventing the platinum
inlay pieces from moving in burnout? How can I do this and
maintain a polish on these pieces? Thanks for your help;

Steve


#11

Bob:

Most responces to my question have been the same - bi-metal
casting. I’ve never tried that and I will next time however, I’m
stuck here as I have already cast the piece and am fitting the
inlays. Rex of OZ has a very interesting idea which I’m going to
try. It looks very clever and, with some clarification, will
fill my need nicely. BTW…How do you polish platinum? I’ve been
using a 240 emery on a flat stick and one grade of fairly fast
cutting platinum polish - seems like to old tripoli we used to
use years ago on gold.

Thanks very much;

Steve


#12

Okay Rex:

You say you cut a “campher” in the inlay channel? Exactly what
do you mean? Is that making the channel wider at bottom and
hammering the inlay piece into the recess? Also, how do you
finish the platinum inlay after hammering it? I find it very
difficult as the platinum is so much harder. I like the idea
however, as I have experienced problems with pitting and
distortion when soldering the inlays in. Never looks
satisfactory, and as mentioned before, I never could finish it
properly. I have seen your posts on several topics and appreciate
all your time in helping all who ask. That’s what makes Orchid
work as well as it does.

Many thanks;

Steve


#13

Dear Steve, thanks for your interest. If “chamfer” was
electronically garbled to “campher”, no wonder you were puzzled.

I originally wrote “chamfer” - at least that’s what we call the
small angled surface that’s filed off a corner in Oz. I guess
it’s the equivalent of taking out that little ream of metal from
the tube ends of a hinge before you rivet it, so’s the rivet
won’t work free. Same with the inlay. Think of it as a funny
shaped rivet, and you’ve got the idea.

You are quite right in your second question: the chamfer is
applied to both sides of the host metal and widens the hole top
and bottom. The inlay metal (in your case, platinum) being
slightly thicker, is then able to be hammered and spread to fill
the chamfered angle so that it presses firmly onto and slightly
overlapping the host metal (your 14ct). No solder, just expanded
tight.

Your question about finishing was a good one and I noticed a
couple of recent posts on polishing platinum which covered the
territory better than I could.

How do I finish and polish platinum? Perhaps it would be most
useful if I answered this in context of finishing and polishing
this particular type of inlaying. Because the platinum inlay is
still a little raised above the surface of the 14ct, I file this
down to the level of the host metal, being careful not to file so
much away that I break through the filled chamfer. I do this with
a fairly fine file, sometimes a hand-file, sometimes a needle
file, depending on the size of the piece.

Because platinum is a “grabby” metal, tending to stick in the
file teeth, I usually “pin” the file with a piece of chalk. A
wipe or two with a piece of chalk reduces the tendency of
platinum to stick in the teeth of the file. Now that it’s
satisfactorily filed, I emery with a 1200 grit emery paper.

Platinum is more difficult to polish - I don’t have to tell you
that. However there is a little trick that I have found useful in
the prepolishing finishing stage. Even though I’m already using
quite fine emery paper (1200 grit), I take a scrap of the same
grit paper and rub it vigorously over the surface of my emery
stick that I’m going to use to emery finish the platinum surface.
In other words I rub emery against emery which gives me a much
much smoother grit to emery the platinum with.

Now I’m ready to polish. The purists will probably throw up
their hands in despair, but I simply use tripoli, then green
rouge, then red rouge - just as I do for gold, and silver (and
titanium for that matter). Getting the platinum down to the
finest emeried finish I can seems to solve any problems of
finish.

Another tip re inlay: If it’s a relatively small inlay, I simply
burnish it with a freshly polished needle (again, polished with
tripoli, green rouge, red rouge) after emerying, before finally
polishing with - you guessed it - tripoli, green rouge, red
rouge.

Steve, I really respect what you guys know about technique and
design. I hope I haven’t oversimplified or too-obviously spelt
out stuff that you may already know and do. Hope this helps. Let
me know if I can clarify further, Regards, Rex from Oz.


#14
 method of preventing the platinum inlay pieces from moving in
burnout?  How can I do this and maintain a polish on these
pieces? 

Hi Steve,

Ideally you want you design to have edges of the platinum
sections exposed so your investment has something to grab onto,
(just like you need keys for the gold to bond with). If not, if
its flush, you can solder on little wires that protude into
investment. I will bend them into little loops on the ends to
make them more rigid during burnout. You are right that this
won’t maintain the polish on the whole platinum section. After
casting I will cut off the pins then rubber wheel the area where
the pin was attached and and use a pink silicon wheel and then
carefully polish the area. Sometimes I use little hard felt
wheels with the different platinum polishing compounds so I dont
disturb the surrounding gold. This takes a little bit of work.
But its less work than soldering in inlays and you have a perfect
seam around the platinum sections, without any solder.

If you do go with the soldering method, its much easier to heat
your platinum sections up a little and push them onto the wax
right where you want them. You may need to temporarily solder on
little pins so you can pull the little guys out again. After
casting they should fit right in and you can then solder, I try
to use hard but may back down if its making the gold sweat. You
are faced with the same clean-up problems with either method. It
is really hard to solder these in and have a perfect seam,
without getting any solder on the platinum. I would clean-up and
polish the same as above, if you are caredul with the rubber
wheels you can keep everything perfectly flat, I like the big
blue ones.

I am still not quite sure exactly what you are trying to do, you
said inlay platinum on the edges of the ring. If its one
continuous piece I would use a different method. I hope you
customer loves it.

Good Luck,
Mark P.


#15

Dear Rex:

Thanks so much for the clarification of your previous post on
platinum inlays. Please don’t be concerned that you’ve
oversimplified your explination as it can’t possibly be too
simply explained to me! I’m bacicly a repaiman seeking new
knowledge in fabrication methods. Long frustrated in the daily
grind of repairing and wishing to be more creative. Still trying
to find my “style” in design. Again, I greatly appreciate the
helpful from you and many others on Orchid hard won
from years of experience.

Be well;

Steve


#16

Dear Mark:

Actually, the piece I’m working on now will have an actual
geometric design inlayed in platinum on both sides. I’ve gone
and cast the ring in 14k yellow already and made the inlays
otherwise, I might use the bi-metal casting method. The design
is in the center of ea. side and since I’ve gone this far, I’ll
simply solder them in and hope for the best. As previously
mentioned, Rex from OZ sent me instructions on hammering inlays
into the piece w/o using solder and I think I’ll try that next.
As usual, I suspect it would depend on the circumstances which
vary with each job.

Thanks again for your kind reply.

Steve


#17

Hi Steve, Yes, there used to be a white diamond Tripoli that was
plat. Specific but I cant find it eney more. Geswien has a
polishing kit but you have to clean in between steps, being very
vigilant about separating the buffs and keeping them clean. I
use Zip lock baggies to keep each step separate. Plat
contaminates so easily,Jergan said “All other metals are like
lead to plat.” meaning the way lead contaminates gold is the same
way plat. is contaminated by other metals, especially cobalt
aloy (its magnetic).

If you make a mechanical bond as well as casting it together it
will help also. Such as a small wire or tab underneath. Good
luck,

Bob
Hoff Jewelers
St. Paul, MN.
Land of ten thousand taxes, twenty thousand lakes that are frozen over 9 mo. a
yr., And giant mosquitos.


#18

Just great! Not only do we have to worry about plat/gold
contamination, but even the alloy used w/the plat. Always used
to be plat/irr and now we see cobalt (a la Stuller) and this new
plat “S” by Kretchmer from Hoover & Strong. And just how are we
to keep everything seperate when doing repairs on often unknown
alloys??? Almost like dealing with synthetic gems! Sigh Oh
well, I guess I should be happy that things are progressing so
fast, keeps the job fresh.

Steve