1) Weigh metals carefully in the proportions listing in gold alloying tables (the larger the amount prepared, the more accurate the karat the resulting gold alloy will be).
2) Pickle all metals to make sure they are all thoroughly cleaned.
3) Mix the metals, except the gold, in a crucible fluxed with borax.
4) Melt the metals with a reducing flame (starting with the highest melting point metal). Do not bring the metal to a boil. Stir constantly with a carbon stirring rod.
5) Keep the metal molten and add the fine gold.
6) Pour the molten gold alloy into an ingot mold or depression formed in a charcoal block.If the resulting gold alloy is brittle when later worked, this will indicate impurities. Streaks of color will indicate that the alloy was not mixed properly and may have to be remelting and remixed with a carbon stirring rod.
Formula for Raising to a Karat
((K1 - K2) x W) / (24 - K1) = Amount of pure gold to add
1) Weigh the gold you want to raise ( W ).
2) Subtract the starting karat ( K2 ) from the desired karat ( K1 ).
3) Multiply the result of step 2 by the starting weight, W.
4) Subtract the desired karat ( K1 ) from 24 (for 24 karat).
5) Divide the result of step 3 by the result of step 4.
6) You now have the amount of 24K gold you need to add to your original karat gold to raise it.Ex. How much 24K gold do you have to add to 7 grams of 10K gold to raise it to 14K?((14 - 10) x 7) / (24 - 14) = 2.8 grams of 24K gold.
Formula for Lowering to a Karat
((W x K1) - (W x K2)) / K2 = amount of alloy you need to add to lower the karat of gold.
1) Weigh the gold to be lowered ( W ).
2) Multiply this weight, W by its karat ( K1 ).
3) Multiply the starting weight, W by the desired karat ( K2 ).
4) Subtract the result of step 3 from the result of step 2.
5) Divide the result of step 4 by the desired karat ( K2 ).
6) You now know how much alloy to add to your gold to lower its karat.Ex. How much alloy do you need to add to 6 grams of 18K to make it 10K?((6 x 18) - (6 x 10)) / 10 = 4.8 grams of alloy.