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24 karat gold has been considered = too soft to=20 manufacture jewelry that will withstand everyday wear. = However,=20 PureGold=92s microalloyed 24K gold has greatly improved = hardness and=20 strength when properly carried through the manufacturing = process.=20 This enables the production of jewelry that can carry a 24K = hallmark=20 in almost all countries of the world and yet retains its = finish and=20 structure in everyday wear. Fabricating a piece of jewelry from PureGold = begins with=20 planning the piece from start to finish. The ability of the=20 microalloyed gold to increase in hardness with cold work = allows one=20 to design the hardness of each part of the piece being made. = The=20 increase in hardness with cold work and intermediate age = hardening=20 steps is shown in the graph. For the maximum hardness to be reached, plan a = reduction=20 in wire diameter or sheet thickness of 90%. A decrease in = cross=20 sectional area in whatever shaped piece of metal you are = working=20 generates a cold worked hardness and, if you desire less = than the=20 maximum hardness, you can generate whatever hardness you = want as=20 illustrated in the figure below. The need for work hardening should be anticipated = in the=20 design stages of making a piece. The amount of cold work = required=20 will vary by the type of item being made. A pin back, for = example,=20 will require significant cold work to achieve maximum = strength. A=20 bezel, on the other hand, should be tailored to the hardness = of the=20 stone that is being set. A fragile stone, such as an opal or = a=20 tanzanite, requires a fully annealed bezel that is worked as = little=20 as possible to retain maximum softness, so the stone is not = damaged=20 during setting. In contrast to most gold alloys, PureGold does = not=20 require annealing when cold working the metal. It does not = become=20 brittle even with a 99% reduction in cross sectional area. = However,=20 should you desire to soften the metal, heating at 600 = degrees=20 Celsius (1112 degrees Fahrenheit) for 20 minutes followed by = quenching will anneal the metal. Assembling components can be the most critical = step in=20 completing a fabricated piece since this step requires = applying some=20 heat to the cold-worked components. As shown in the figure = below, a=20 cold-worked , age hardened piece loses some of its hardness = upon=20 heating. We produce a 22K solder that will join the metal = at 425=20 degrees Celsius (797 degrees Fahrenheit). This low melting = solder=20 does not significantly decrease the cold worked hardness of = the=20 pieces to be joined and, can be carried out at the beginning = of the=20 age hardening process. The hallmarking laws in the U.S. allow an article = to be=20 stamped 24K if the gold content is at least 0.997 gold and = there are=20 no solder joints. For a fabricated piece with solder joints, = the law=20 requires a purity of 0.993 gold for a 24K stamp to be = applied.=20 Therefore, when designing a piece to be made from PureGold, = keep the=20 number of solder joints to a minimum. The following = illustrates how=20 one can calculate the amount of solder allowed in = manufacturing a=20 piece.
Once a piece has been fabricated, it must be age = hardened=20 in order to obtain the maximum level of hardness and = durability. Age=20 hardening requires heating the piece to 250 degrees Celsius = (482=20 degrees Fahrenheit), holding it at this temperature for = three hours,=20 and then air cooling. When using an oven for the soldering=20 operation, the age hardening step can be carried out = immediately=20 after soldering by dropping the temperature and following = the same=20 procedure. Age hardening does not result in oxidation or=20 discoloration. Finishing a piece made from 24 karat microalloy = differs=20 somewhat from finishing a 14 karat piece. If you treat it = like a 14=20 karat piece, you won=92t get a smooth surface; the process = is the=20 same, but the number of steps is greater. In fact, polishing = 24=20 karat microalloys is similar to polishing platinum. = A fine finish is obtained by proceeding through=20
progressively finer abrasives =96 200 grit, 400 grit, 600 =
grit, 800=20
grit and 1200 grit =96 before a final rough polish. When =
applying the=20
rough polish, use a light touch. Applying too much pressure=20
generates heat and does little to polish the metal. In fact, =
it=20
allows the surface of the metal to soften somewhat and does =
very=20
little polishing. Like platinum, microalloys respond well to =
cross=20
buffing. If you desire a matte finish, the graded papers =
available=20
in 2,000 grit, 4,000 grit, 6,000 grit and 8,000 grit allow =
you to=20
add varying degrees of fineness to the finished product.=20
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