HOW TO MELT GOLD
Here are a few basic steps for melting refined gold in graphite crucibles and fused silica crucibles.
Note: These instructions are for refined gold that has been separated from the ore, or the fines and chips jewelers wind up with after repairing or resizing rings, etc. If your gold is still bonded to rock or metal, just out of the earth, you might want to read up on smelting gold first.
1) Gather together the things you will need: the refined gold for melting, a high heat torch or an acetylene torch, a torch igniter, either a graphite crucible or one made of fused silica, borax powder, a stirring rod, crucible tongs, an ingot mold, a tripod stand, a high heat frame, hot gloves, and eye protection.
2) Put a little borax powder into the crucible and completely dust-coat the insides of the crucible.
3) Use the torch to preheat the crucible for a few minutes before placing the gold into the crucible. This will help to keep from cracking the crucible due to thermal shock.
4) Once the crucible is hot, slowly add a little gold and gently bring the torch flame to the outside or bottom of the crucible.
5) Heat the gold with the torch from the bottom or sides of the crucible, not from the top. The ignited gas from the torch may blow light powder, chips or shavings around.
6) Run the torch flame across the top surface of the gold ONLY when it is molten and fluid.
7) Use crucible tongs to grab the hot crucible. DO NOT grab the hot crucible with the hot gloves, they are not made to withstand that kind of heat.
8) Pour the molten gold into an ingot mold, or your own mold. Make certain to form the gold while it is still hot. If the gold begins to cool you will have to re-melt it.
9) Do not set a hot crucible on a cool surface. The crucible will crack.
10) Once the gold is in the mold let it cool and harden.
Quartz stirring rods may be used to collect and remove slag.
What is slag? Slag is a by-product of metal smelting. It is the impurities naturally found in metal ore. Slag floats to the top during the smelting process, and looks like little rocks. When the metal is fully melted a stirring rod is used to skim the slag and remove it from metal.
MELTING TEMPERATURES GOLD ALLOYS
The melting temperature of gold depends on the alloy. The various alloy recipes create variations in gold melting temperatures. Gold is generally mixed with silver and copper plus trace amounts of other metals to form the jewelry alloys. White gold often has nickel or palladium and the melting temperature is higher than for most yellow golds.
Yellow Gold Melting Temperatures:
10k yellow gold - Around 1617° F - 1650° F (881° - 891° C)
14k yellow gold - Around 1524° F - 1606° F (829° - 874° C)
18k yellow gold - Around 1679° F - 1765° F (915° - 963° C)
White Gold Melting Temperatures:
10k white gold - Around 1822° F (994° C)
14k white gold - Around 1737° F (947° C)
14k white gold with palladium - Around 1968° F (1076° C)
18k white gold - Around 1704° F (929° C)
18k white with palladium - Around 2006° F (1097° C)
A propane/air flame burns at 3590° F (1,980° C)
A propane/oxygen flame burns at 4,087° F (2,253° C)
An oxyhydrogen flame burns at 5,072° F (2,800° C)
An acetylene/oxygen flame burns at 6,332° F (3,500° C)
These instructions are general in nature. Your application may vary. Proceed with the utmost of caution, and at your own risk. QTE North America, Inc. assumes no liability derived from the use of any of these products or from following these basic instructions.
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Melting metals is dangerous. ALWAYS wear appropriate safety protection.
(c) QTE North America, Inc.
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