![]() |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||
About Bi-Metal
18K Yellow on Sterling Silver - 22K Yellow on Stering Silver To better understand the history, traditional uses, and manufacturing technique of mechanically bonded metals we are including the following paragraphs from pages 16 and 17 of the Handy Book of Precious Metals by Handy & Harman. GOLD FILLEDGold for the millions: The possession of gold in any of its forms was, until recently, a rather exclusive privilege. However, an “accident” in a silversmith’s shop more than 200 years ago set the stage for the popularization of gold, putting it within the reach of millions. This accident led to the development of gold filled, which is an overlay of 10 karat or better bonded by heat and pressure or reinforcing metal. THE ORIGIN OF GOLD FILLED The silversmith was Thomas Bolsover, of Sheffield, England, who, while using a copper coin as a shim to hold a silver knife in a vise, discovered that after several hours of clamping, the copper had fused to the silver. This mechanical bonding process would later be used to fashion fine heirlooms (using minimal amounts of silver bonded to less costly metals) which not only exhibited the beauty of a precious metal, but was also affordable to wide stratum of the population. HOW GOLD FILLED IS MADE Gold filled is produced by fusing a layer of karat gold to a suitable supporting metal (or alloy), using equipment that carefully controls pressure, heat, and time. The bond produced is a permanent one. REQUIREMENTS FOR GOLD FILLEDGold filled products must consist of at least one layer of karat gold. The minimum karat for this layer is 10 karat gold. This must represent at least 1/20th the total metal weight. Rolled gold plate is material consisting of layer or plating of 10 karat gold or better. The proportionate weight of the karat gold may be less than 1/20th (1/30th, 1/40th, or as the case may be). 18K Yellow on Sterling Silver Bi-MetalHALL MARK1/20 18K/Stg GF DESCRIPTION AND USEA layer of 18 karat gold alloy with a rich yellow color is bonded with sterling silver to form a sheet of precious metal with two distinct surfaces. The gold layer is similar to that of most gold filled products and has comparable working characteristics. However, such surface treatments as engraving, scraping, folding, and twisting can be used to accent the two surfaces. COMPOSITION
MELTING POINT
ANNEALING TEMPERATURE1140 °F to 1300 °F SOLDERING On gold surface use: 14K or 18K yellow easy (soft) solder MECHANICAL PROPERTIESSimilar to sterling. DENSITYSpecific gravity (grams per cubic cm): 10.53718Ounces per cubic inch: 5.5516
STOCK SIZES Sheet and circles: 20 and 24 gauge 22K Yellow on Sterling Silver Bi-MetalHALL MARK1/8 22K/Stg GF DESCRIPTION AND USEA layer of high karat gold alloy (22K) with a bright yellow color, close to that of fine gold, is bonded with sterling silver to form a sheet of precious metal with two distinct surfaces for finishing. The gold layer which is two to three times thicker than most gold filled products gives this product more workability than usually associated with gold filled products. Such surface treatments as engraving, scraping. Folding and twisting can be used to accent the two surfaces, as well as burnishing and chasing which are possible because of the heavier layer of gold. COMPOSITION
MELTING POINT
ANNEALING TEMPERATURE1140 °F to 1300 °F SOLDERING On gold surface use: 14K or 18K yellow easy (soft) solder MECHANICAL PROPERTIESSimilar to sterling. DENSITYSpecific gravity (grams per cubic cm): 10.9367Ounces per cubic inch: 5.7621
STOCK SIZES Sheet and circles: 18 and 24 gauge |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Phone: (800) 462-7447 - Fax: (800) 535-3829 - E-Mail: support@hauserandmiller.com |