Gold-Filled: Fancy or Farce
The Federal Trade Commission has banned the sale of anything less than 9Kt. gold, as karat gold. Otherwise you'd be buying 1Kt. 0r .1Kt. gold junk jewelry.
The worst of gold jewelry is electroplated gold, but that depends on the thickness of the plate, which is low to begin with and must be polished, making the gold by weight and volume less. Quite better is so-called 'gold filled,' a source confusion among buyers and of profit among jewelers.To be sold as 'gold-filled,' the gold must be physically applied, and that is done thusly: A one-inch thick gold rectangle of, say, 12Kt. gold of any dimensions, is rolled out thinly, and soldered to the base metal, usually copper, (or nickel) with a thin sheet of about .0025" thick solder. After melting the solder and sealing the gold to the copper you have 'gold filled.' But only on the top! Some work has to be yellow-plated to cover up irregularities at the interface of top and sides, called the 'edge effect.' If you want 1/20 12Kt. (1/40 24 Kt.) 'gold-filled,' commonly called "12/20," you roll a one-inch thick rectangle of 12Kt. gold so it is 1/20 of 12 Kt. gold by weight in proportion to the base of 19/20 parts copper by weight. Gold is heavier than copper, so that proportion can be misleading. The lighter/heavier the base, the thicker/thinner the rolled gold by volume must be. 'Gold-filled' anything is cheap jewelry with some notable redeeming qualities: It looks good, and it makes good chain, because the gold/solder/copper can be wrapped around itself so there is no 'edge effect' to cover up. And now there is 'double gold-filled' with a layer of gold on both top and bottom, but there is still, an 'edge effect' to deal with. As far as pure gold goes, there is little practical application, except in things like .999 fine 'gold leaf ' that woodworkers use to accent carved letters in wooden signs or plaques. It is so soft it is applied by deftly painting it on with an artist's paint brush.
Pure gold is also made into coins for collectors and bricks for alloying with other metals, or for a store of value like Fort Knox at first had 'backing' the dollar. (Economist Paul Samuelson suggests it is now the dollar that backs the gold, not vice versa.)
Finally, the base for any gold content item is copper or nickel, and never brass--that's an alloy itself containing zinc, which is a troublesome metal to do anything with.
The worst of gold jewelry is electroplated gold, but that depends on the thickness of the plate, which is low to begin with and must be polished, making the gold by weight and volume less. Quite better is so-called 'gold filled,' a source confusion among buyers and of profit among jewelers.To be sold as 'gold-filled,' the gold must be physically applied, and that is done thusly: A one-inch thick gold rectangle of, say, 12Kt. gold of any dimensions, is rolled out thinly, and soldered to the base metal, usually copper, (or nickel) with a thin sheet of about .0025" thick solder. After melting the solder and sealing the gold to the copper you have 'gold filled.' But only on the top! Some work has to be yellow-plated to cover up irregularities at the interface of top and sides, called the 'edge effect.' If you want 1/20 12Kt. (1/40 24 Kt.) 'gold-filled,' commonly called "12/20," you roll a one-inch thick rectangle of 12Kt. gold so it is 1/20 of 12 Kt. gold by weight in proportion to the base of 19/20 parts copper by weight. Gold is heavier than copper, so that proportion can be misleading. The lighter/heavier the base, the thicker/thinner the rolled gold by volume must be. 'Gold-filled' anything is cheap jewelry with some notable redeeming qualities: It looks good, and it makes good chain, because the gold/solder/copper can be wrapped around itself so there is no 'edge effect' to cover up. And now there is 'double gold-filled' with a layer of gold on both top and bottom, but there is still, an 'edge effect' to deal with. As far as pure gold goes, there is little practical application, except in things like .999 fine 'gold leaf ' that woodworkers use to accent carved letters in wooden signs or plaques. It is so soft it is applied by deftly painting it on with an artist's paint brush.
Pure gold is also made into coins for collectors and bricks for alloying with other metals, or for a store of value like Fort Knox at first had 'backing' the dollar. (Economist Paul Samuelson suggests it is now the dollar that backs the gold, not vice versa.)
Finally, the base for any gold content item is copper or nickel, and never brass--that's an alloy itself containing zinc, which is a troublesome metal to do anything with.
posted by Tom at 1:15 PM
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