Understanding
Plumb Platinum Solders
90%
or More Pt In a True Solder
Developed
By Precious Metals West
Written by
Daniel Ballard
Soldering,
(as opposed to welding) is using a low temperature material to bond or
fill materials in an item.
What
does Plumb mean in Solders?
As far as actual precious metals content goes, solder is the least
understood material we use! When the precious metals content in the
solder matches or is superior to the jewelry, we call it plumb. Otherwise
we call it repair
grade solder. Different makers of solder do use somewhat different
terminology for low karat solders, but plumb always means at least
matching the precious metal content between the solder and the jewelry.
As we know, platinum jewelry normally runs from 90% to 95.2% Pt. To understand
plumb platinum solder, I must
also talk about gold solders a bit for comparison. When we consider gold jewelry
in the United States, we see gold content run from 41.66% (10KT) to 75% (18kt)
with some exceptions, such as the very rare 91.66% (22kt) and some imported
jewelry that may be as low as 33% gold. You can see that in nearly all instances,
we have a lot of alloy to work with in creating solders for gold compared to
platinum.
For decades now we have been accustomed to gold solders that run in
gold content from 25% to 80% gold. In previous years way back when, we only
had gold solders that had a lower content than the jewelry. One example is
how jewelers used to mix 1 dwt of silver solder with 1 dwt of 14k scrap. This
gave them a 7kt yellow solder with a low flow temperature. In
more recent times we have been able to use cadmium to reduce the flow
temperature of solders. That fairly toxic material allowed high quality
solders to be made in Plumb grade. Other very low melt elements
are used instead of Cadmium. Tin is sometimes used. Indium is a very
common element in the solder trade. In fact indium has been used by
PMWest, my employer and by my employers father (at the old PMR co.
in Buffalo) since the very first days instead of cadmium. For 14kt,
or even 18kt, we have a lot of alloy we can use to get the color, strength
and low characteristics we desire.
The
gold content in gold solders varies a lot from maker to maker.
Unlike jewelry, gold solders may or may not be stamped with the
gold content. Plumb
solders of course are. What we call repair solders in gold and platinum,
the precious metal content is adjusted solely for either melt and color,
or at the wholesale level… price. Then the solder is marked
with either the intended use
like 14ye or stamped with the flow temp like 1100 pt solder.
In this paper I will address the previous conventional platinum
solders as Repair
solders and the new solders as plumb. This is similar
to what we are all used to in gold solders.
A
few rhetorical questions
What
is really in solder? Silver
of course in varying amounts but lots of silver.
What
is really in solder? Lead of course, even though we use
it on copper pipe most often!
What
is really in gold solder? Gold, and most often in the same percentage as
the rest of the jewelry.
What
is really in Platinum solders? A different story.
In what should be called platinum repair solders, a necessary lack
of Platinum causes the addition of substitute metals intended to pull down
he flow temp while providing color and strength. All of us in the platinum
solder trade use substitute metals for flow and or color. Bench jewelers must
be very careful about what brand of solder they use so as to avoid problems.
One gets accustomed to a particular brand of solder, and any change requires
adjustments along the way. All of these shortcomings help the new laser solder
machines look good. In addition to keeping the heat close to the work, a laser
welded joint matches color perfectly. The cost however is still in excess of
$20,000 for each machine. Many jewelers tell me of how they learned to weld
rather than solder platinum due to quality concerns. They want the best finished
result they can get.
Lets
examine the metals we commonly substitute for platinum to make repair solders.
1.
Nickel-Remember all the trouble cause by Nickel in
white gold? We usually work to keep nickel out of jewelry where it
is practical to do so. Europe prefers no nickel at all.
2.
Silver-This is hardly
a metal commonly associated with platinum jewelry, but it provides
important properties to conventional platinum solders.
3.
Palladium-Too high a melt
temperature to help much at all, but it is the very common element
found in higher temperature solders. In recent months cost has become
a big factor with this important element.
4.
Gold-Wrong
color and too high a temperature to solve the flow.
These repair solders do have shortcomings
Poor
color, porosity and some very visible seams just to name a few. This is
often fixed with rhodium plating, but that is another unneeded expense,
and rhodium will wear off with time, which can disappoint the buying public. Due
to the unique nature of platinum, we always had to compromise the platinum
content of the solders.
Sometimes
in the higher temps we find some Platinum but only rarely below 1500C.
In these solders we do not find platinum content even closely approaching
the content in the jewelry. I must point out that all of the above applies
to the solders made by PMWest, just like anyone else making solder for
use on platinum.
At
1500C there is typically from 10% to as little as 0% platinum content.
Platinum
solder rarely really deserves the title platinum. As shown before we usually
name a solder by its main ingredient rather than its use. Ever heard of copper
solder?’ Of course not plumbers and electricians use lead solder
for that. I do not mean to imply any deception was ever intended. Platinum,
as we well know from bench work and casting is a very different animal
than gold. Astronomic temperatures cause all kinds of difficulties,
many of which are best solved by solutions published by PGI! I refer
to all those books from previous platinum days.
Rumors
and Concepts
In
late 1998 after presenting a paper for PT day west, I had a meeting with
my boss Keith Weinstein. I wanted to do another paper for PGI. We discussed
a few ideas then I brought up a long shot possibility.
At the time rumor had it that the new Heat treatable S+ platinum
developed by Steven Kretchmer melts below 1700C. perhaps close to 1600C. –This
was the first commercial casting grain with the lower flow temperature. Really,
in common experience there were no platinum alloys with low flow temperatures
at all. Once the fact that this could be done at all was commonly known,
many possibilities emerged and will continue to do so.
The
possibility of using that metal as a solder came straight to mind, but
a solder that is too hard creates problems for finishing, and 1600 is not
a very low temp for a good Pt solder. But
the seed was planted.
I
suggested that if we applied 30 years of solder making knowledge to
the principles found in S+ and published JM alloys, we could
develop plumb
platinum solders. After taking a look at our own solder formulas ideas
took real shape.
Keith’s
reaction was predictable. If this was so easy why was it not done before?
I reminded Keith that even though solders had been out a long time,
S+ was very new . I also realized that very little had been done
for decades due to that fact that platinum had been out of common
use for so very long. Keith then really hit the books. More detail
about the development story can be found in the upcoming Ptday
west 1999 book. That
paper is titled Developing Plumb Platinum Solders. Keith
found the work done by Johnson Matthey, Steven Kretchmer and papers from
PGI to be very helpful. In fact, only personal time constraints kept Steven
from working with us on this new product.
The
Marketplace
My
feeling was that for a viable line of products we needed easy medium and hard grades
of solders. That means three distinct flow temperatures, all as low
as possible. Keith was able to invent one kind of viable alloy that
did what we needed. The obvious thing to do was vary the Pt% for flow
temp purposes. There were many things to evaluate. We discussed a few
formulas. The form the new solder would take would be the familiar
sheet, rolled fairly thin and cut into single dwt pieces. One oddity
of solder mfg is that we must make the product reasonably attractive.
Jewelers expect solders to have a clean almost polished appearance.
This despite the fact that the very same jeweler is going to melt the
solder one chip at a time. With
some sense of what we needed, we called our man at the shop in charge of
rolling mill operations.
When
creating a new product your best people are critical. Robert Lumabao brings
10 years of shop experience to the task. Keith gave the initial test formulas
to Robert, who began with the 95% Pt solder. The picture shows one example
of failure. The other shows Robert at his home away from home.
 |
As
Robert worked his way through some predictable properties emerged. The
higher Pt content material is easier to roll out than the lower. This is
consistent with solder mfg in gold. The metals we use to lower the flow
temperatures of solder can make the ingots very brittle. This is true in
most precious metal solders. With time and effort we were able to roll
out sheet plumb solder.
We
gave the initial test solders to a local trade shop jeweler, who faces
a wide variety of assembly, sizing and repair jobs. His reports were extremely
encouraging. We then began a wider series of tests, all based on real world
circumstances. Many thanks to the local LA jewelers who tested and reported
to us.
A
month or so later, at Kraftwerks 1999, I set up a soldering bench with
some scrap platinum jewelry and the brand new solders. This
was a chance to ask the
experts who were present at Kraftwerks that day to assess the new solder.
Anyone
who wished to try the solder was given the chance. This included myself,
despite a near complete lack of bench experience. Oddly enough, I can
work with this solder in platinum easier than I can work in gold
soldering. Once I got used to the safety goggles, the soldering
is simpler. There is no oxidation or flux to be working around.
The hot color makes it easy to see when the solder flows. My feeling
is that this will allow the less platinum
experienced jeweler to have an easier time soldering.
Christian
Tse was very helpful. He tried the solder at the bench I set up, and
helped determine flow temperatures. When I needed pictures of the
solder being tested, he graciously invited me to his studio. Once
I arrived and set up my camera, he soldered a couple of pieces
of bar stock that had been cast. In the end, the joint was strong,
and cleaner than the rest of the host material. Unfortunately,
the casting was not as nice as we might have hoped. As we examined
the polished solder joint under magnification, we saw pinholes
all across the surface EXCEPT for the joint itself. The joint color
was a naked eye match.
Jurgen
was very helpful (of course). He
was another of the first to try the new solder at Kraftwerks 99. We
sent samples to a variety of designers and jewelers who work in platinum.
Those who found the time, and were kind enough to call reported favorably
on the solder.
How
to use the Solder
With
time and testing we established approximate flow temperatures and found
where we must be careful with how we use the solders.
As
was suspected, this solder requires no flux. The very high purity seems
to take care of any problems in the alloy as far as oxidation goes. We
found this solder must not be used like one uses gold solder. By that I
mean that this solder is fairly viscous, unlike gold easy flow solders.
The new platinum solder stays close to the joint.
All
reports of discoloration have been heard from jewelers who pick
this solder up as a molten ball with a titanium or tungsten pick.
This would imply that those metals either alloy into or somehow
discolor the solder. We
are not claiming a perfect color match, just a much improved color,
particularly at lower flows.
All
this really means is that you must use some other way to place the solder
at the joint. One trick is that red hot platinum is sticky by nature. Flux
can disturb the surface finish, so is not suitable for keeping solder in
place. With sizing there is no problem as long as you have enough tension
in the joint to hold the slice of solder. One important advantage to the
new solder is the superior color match at the lower flows. This allows
one to melt the solder all the way through a shank without fear of melting
the ring shank itself.
The
color is extremely close. When we examine the color of the seam carefully,
the color can show on large areas where the polished area is large or where
we have satin type finishes. However, the color is as close or closer than
anything else in the solder market, particularly at 1500C. or lower. The
only way to truly match color is to match ingredients, which would make
solder impossible to make.
The
present available formulations are as follows
PT-E is 90% Pt, and 10%
alloy, and flows in the 1300C
range-Our easy flow solder. As the name implies this is our
easy flow solder that is plumb (same content as the intended
jewelry) to all the 90%Pt/10% Ir or Ru or whatever. Its color is closest
to 90/10 of course.
PT-M
is 92.5% platinum. The way to increase the flow temperature was to
increase the platinum. This material flows in the 1400C range.
This is our medium
flow
solder. Its color works with any kind of platinum jewelry, but is only truly
plumb to 90/10 jewelry.
PT-H
is 95% platinum. The highest flow among the new solders, it flows at
1500C or a bit less. We call it the hard flow solder, despite the fact that
its flow temperature is hundreds below the flow of ordinary casting platinum.
It is
plumb or better to all platinum jewelry. An ironic twist to this formula….
It may be a bit whiter than 90/10 jewelry. In certain items this can
be an issue.
Easy,
Medium, and Hard is one way to look at the solders. Another is to simply
go by the Pt content and match whatever you are working on. That is ideal
for color, and works fine when you only need one flow to do a repair. This
solder is the closest color match simply due to matching the platinum content. .
Scientific testing may show that our flow temps are a bit off. The tests
we find most valuable are those performed by jewelers at their benches.
After all, those are reality based. Scientific tests have huge value, but
can be misleading to apply at the bench. Many theoretical advances in metallurgy
have not worked as well as indicated by the tests.
A
word about the alloy Keith decided on … This alloy contains Indium, Copper,
and
LF. LF is the designation for an element that can be found
in the patent application. As this time we are Patent Pending so we
are not specifically naming that element in this paper. Keith has decades
of experience working with Indium.
The physical strength of this solder is very high. Like any solder the strength
depends on the quality of the surfaces and the technique used by the jeweler. Again,
our tests were performed on actual jewelry which was abused in
typical consumer fashion. I suspect that furnace assembly can
be accomplished with the easy flow. That would be an advantage for
those who stamp and assemble platinum settings for diamonds. I refer
to those peg base heads we use in wedding
sets. One will notice the solder sheets themselves are quite hard and springy.
That is because they get so work hardened during manufacture. The solder will
not polish out leaving a seam. In rare instances, like
when the newly soldered joint cools very slowly, some ridging can
be found. Lightly abrading the ridge, then lightly burnishing around
and on the joint, followed with normal polishing can easily address
this. Another approach is to heat the item to annealing temperature
and quench. All of the flows indicated are determined by comparison
melts, not scientific analysis. This would be unusual among our large
competitors. The equipment that precisely determines true flow temperatures
is quite expensive and rare. However, time and again real world testing
has proved the validity of new products.
Plumb
solder works well on all common platinum alloys. That includes Iridium,
ruthenium, palladium, cobalt and copper. A possible exception may be
the new lower flow temperature platinum ’s such as Hoover & Strongs S+.
By the way just like plumb platinum solder, S+ is
a trademark product. Due to the low melt of these casting and fabricating
metals, the usual spread between the host platinum and our solder is
reduced. By the way, I want to point out that all high temp solders
have a potential problem with some platinum alloys-Simply based on
the relatively low melt temperature.
Polishing platinum is a renowned challenge. A common frustration with repair
platinum solder is the tendency to polish out and leave a seam. Plumb solder
more closely matches the rest of the item.
Cautions
and Disclaimers
As
an individual and as a professional I encourage all who use solders to
do so only with proper ventilation. Safety can not be overemphasized. Arrange
your work in such a way as to breathe the cleanest air you can. Where
I live, in Los Angeles, the solder may actually improve
the air quality.
I
also want to caution jewelers who size and repair jewelry made with
the low flow
Heat treatable platinum’s. You
may be in for a nasty surprise one day. What I fear is the fact that
ordinary
platinum repair solders that flow well below the melt of HT
platinum do not have the best color match, and may very well polish
out of heat treated platinum. Yet if one tries to use 1700 repair solder
(a much improved color match) on a platinum alloy that melts at 1600,
well we can hope that no delicate ears are present, and one has a mold
of the style in work for a recast. Consult
the makers of these alloys when practical to do so.
Material
Safety...
When
we examine the material safety issue with the plumb solders, we
can be assured that none of the elements used are known to be a
serious health risk when used as directed. The LF element we use has a vapor release temperature well
above the temperatures during indicated usage. This minimizes the vapor
concern. Toxicology investigations show a low order of toxicity. The LF material
Causes readily reversible changes which disappear after end of exposure. The TLV or threshold
limit value is not established. In a typical shop, this is among
the least threatening materials we work with. The indium we use in
the solder is well understood to be a valid replacement for cadmium,
and is found in many gold and silver solders, and even some other alloys.
Safety
Issues
•
Eye protection is needed just like any Pt solder.
Always
protect your eyes, do not allow the day to day routine to dull your safety
awareness.
•
Always use good respiration or ventilation when melting solders.
Our lungs are not tolerant of vaporized metals.
While the ingredients of our solder may not be particularly hazardous when
used as directed, jewelry solders cannot be researched like common consumer
products. Ventilate as appropriate to your shop.
•
Like all PMWest products-This solder is cadmium free. Our
experience with alternatives teaches us to be careful regardless of
the ingredients used. But, many solders from other makers do include
cadmium, with its well documented hazards.
Remain
aware that these temperatures can be dangerous if anything goes wrong with
the torch or metal handling.
Looking Ahead
We
have not yet developed a plumb platinum solder that flows at 1200 or
less. So,
oxidation of the cobalt in certain alloys will still be an issue. Except
at the joint of course. With some further technical assistance
from friends in the trade we will establish precise flow temperatures,
and more detailed physical information. However we believe this revolutionary
alloy can be used in 75% to 87% platinum solder (below plumb content
unfortunately)
for far lower flow temperatures, while still maintaining a very favorable
color and behavior. The reason we have not yet tested these is that
we have been unable to get the lower platinum solders to roll out.
This is where we need some help. I ask that those who share our interest
in plumb platinum solder, or who can improve the state of the art work
with us. In
this vein I want to mention that we have a huge commitment to platinum
research at PMWest. Our research with platinum includes the newest
rapid fire investments, room temperature flask casting, and even diamond in
wax
platinum casting. Considering our small size as a company (9 employees)
we are stretched a bit thin. We welcome any input on improving this new product.
After all we only began testing less than 10 months ago.
Thanks
to MJSA, PGI, and Jurgen for putting on this premier symposium.
