February 1998

Precious Metals: Metalsmithing



Hard new alloy Plat/SK promises more lustrous, shiny jewelry that's easier to polish and has a longer lasting finish and - very likely - a lower cost. Plat/SK is expected to go on sale this month


A new harder platinum alloy, trademarked Plat/SK, has been invented by Steven Kretchmer of Steven Kretchmer Designs, Palenville, NY. The alloy should be available this month, distributed through Hoover & Strong, Richmond, VA. It will be available in the distributor's next catalog.

You can sell Plat/SK jewelry as the latest and most exclusive platinum available. This 95.5% pure platinum product is extremely hard in the as-cast condition and can be made harder by subsequent heat treatments. Plat/SK promises several key benefits, say designers who have created jewelry with the alloy.

Left: These rings by Michael Sugarman of Michael Sugarman Designs, Santa Fe, NM, were created with the Plat/SK alloy.

Right: Michael Good Designs Inc. of Rockport, ME, used Plat/SK to create this mini-icicle pendant.



The metal is beautiful, says Kretchmer. Consumers will be attracted to the mirror finish designers and manufacturers can create with the alloy, he says. Manufacturers will notice Plat/SK is crisper and dryer than other alloys.

Plat/SK is easier to polish and, once polished, retains its finish longer. The ease of polishing will save manufacturers about 20% in labor costs, says Jean-Francois Albert of JFA Designs, Irvine, CA. Albert tested Plat/SK and has incorporated it into his bridal line. As manufacturers begin to work with Plat/SK, Kretchmer hopes they'll pass the labor-cost savings on to consumers.

Jewelry makers can design lighter, thinner pieces using less of the alloy. Because the alloy is harder than other platinum alloys, lighter jewelry made from it will suffer no loss of durability, nor will it dent or bend. It's springy and slides smoothly upon itself for clasps and other mechanical parts. Other platinum alloys grab and drag.


Plat/SK Launch

Plat/SK is a derivative of the alloy Kretchmer developed for his well-known tension settings. Kretchmer was granted two patents by the U.S. Patent Office for the alloys and heat treatment process he uses in his tension settings, properly called "metal compression-spring gemstone mountings." The designer has a patent pending for the Plat/SK alloy as well.

Hoover & Strong hopes to have the alloy available this month in two grades. One grade is more useful for casting, while the other lends itself to forming or milling. (Milled products are great for fabricating, stamping and anticlastic forming.)

Along with Albert, Michael Sugarman, Michael Good and Richard Messina have tested Plat/SK; designers Eddie Sakamoto, Diana Vincent, Whitney Boin and Michael Bondanza were experimenting with it at press time.

Consumers will learn about Plat/SK from Platinum Guild International. PGI plans to promote Plat/SK as one of the highest purity platinum alloys available. "PGI only promotes high-quality platinum," says Lisa Labrado of PGI. Promotions are still being worked out, she says. Seminars on how to sell this new platinum alloy are will be available from PGI.


Bench Plus

Bench jewelers will see differences when working with Plat/SK instead of other alloys, say those who've already experimented with it:

  • Plat/SK is harder than iridium, ruthenium and cobalt platinum alloys. Standard platinum alloys drag, stick and damage tools. Plat/SK machines better with less tool wear, say Hoover & Strong machinists and manufacturers who've worked with the alloy.
  • Plat/SK polishes like 18k gold, though the polish won't deteriorate like it can on gold. "This cuts anywhere from a third to half off the finishing time," says Sugarman.
  • Soldering lines can be less visible from polishing.
  • You'll be able to make thin, hollow pieces that won't dent or bend. With regular platinum, these types of pieces are fragile.
  • Plat/SK is good for clasps, pin stems and other objects that need to be springy. Parts for catches and clasps from previous alloys drag and grab.
  • Plat/SK doesn't spring back when passing from elastic range to plastic range.


A Few Cautions

As with any new development, there are a couple of disadvantages, says Sugarman:

  • During heat treatment or soldering fabrication, Plat/SK develops a slight patina. This patina can be removed with an acid dip or slight polishing. Kretchmer is working to refine the alloy and eliminate this problem.
  • There's potential for fracturing. As a metal becomes harder, it grows less malleable - and the potential for fracture under "stressful deformation" (also known as bending) increases. Manufacturers can resolve this problem by annealing the metal more often.


- by Lorraine M. Suermann

Copyright © 1998 by Bond Communications.


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