While nickel based white gold is commonly
used and very well understood, palladium based white is gaining interest
and sales. Some of us sell to the EU or Japan, and some of us have customers
sensitive to or about nickel.
Palladium white gold alloys have some
general characteristics. Aside from gold and palladium, copper and silver
are usually contained in the alloy. Different alloy suppliers will reflect
different conclusions as to the "best" ratio of these metals, and many have
innovations that affect behavior. Many of these innovations are in trace
elements, held here as confidential. The effect of trace elements on color
is usually invisible or designed to push the color whiter.
In this instance we have assembled
some of the older formulas useful as a general color guide. As you might
expect the higher palladium content is reflected in a whiter or perhaps grayer
tone. Ordinarily the palladium content is from five to twenty five percent
of the 14kt. In 18kt we see about 12 percent most often. This is reflected
in the color coordinates of the samples.
The profound benefit of palladium
is its softness for fabrication, setting, or engraving. Another advantage
is the evidence that few if any people show any allergy or sensitivity.
I suggest 12% palladium in 18kt gold, and at least 8% in 14kt and at least
11% in 10kt. In 10 and 14kt more is better, but that brings us to the biggest
problem with palladium.
The primary disadvantage of palladium
is that it can add twenty to fifty dollars per ounce to the cost of casting
grain. This varies by the amount of palladium used and the market. If for
any reason palladium costs escalate dramatically, the added costs will increase
proportionate to the market price, just like gold. Secondarily, some special
handling during high temperature smelting or casting is often required and
added refining costs can play a part.
To estimate the added costs of palladium
per ounce simply multiply the London Market price for Palladium by the expected
percentage contained in the karated gold. $200 market at
12 % Pd is $24 per ounce of alloyed gold in added cost as compared to nickel
white gold.
Palladium gold melts at 2000F or higher.
This can cause problems for ordinary investments. Some casters use a platinum
investment which easily handles the extra high temperatures in nickel or
palladium white golds. I suggest a starting point as 2050F for casting our
palladium white golds. We sell SuperSonic for this purpose.
Palladium does not fill as well as
yellow gold, so sprue accordingly. I suggest big sprues arranged for the
lowest workable flask temperature at casting, hopefully about 900F or even
less.
You must use palladium based solders
on palladium white gold. Otherwise someone sensitive to nickel will get the
symptoms of nickel dermatitis from the solder used to make their ring or
earring. We do have two new palladium solders for palladium gold. Of course
laser weld when you can.
I hope this tech sheet is helpful,
please do call with any questions that may remain.
Daniel Ballard
800-999-7528
Daniel@preciousmetalswest.com
©2007
Keith Weinstein Inc.
WWW.PMWEST.US
