Something Old – Something New

Tom Weishaar

 

1.  Every now and then I turn into a sucker.  Recently, a very nice young lady came into our store with a pile of old jewelry and a sad story.  The girl said she had very little money, but she did have a bunch of old broken jewelry that had been collected from her relatives.  She wanted to have the gold melted down and made into wedding bands so that she and her fiancée could get married.  There are times to make money and there are times to help people.  I thought you might like to follow along as something borrowed is turned into something new.

 

2.  There are many rules to follow when reworking old metal.  One of the most important ones is to always cut out any sections of metal that contain solder.  Solder will cause your new gold to become brittle and will lower the purity of your work.  I always take great care to separate out any sections that have solder in them.  Also, I never combine white and yellow gold.  These pieces of unusable metal were put into my scrap can to be sent to the refiner.

 

3.  I could cast the new rings, but I enjoy fabricating much more.  My first task is to heat both my ingot mold and ceramic crucible.  The ingot mold needs to be very hot when the molten gold is poured into it.  A cold mold will cause the metal to freeze instantly.  This will cause a very tight, small, grain structure that will be brittle and crack when I forge it.  I like my ingot mold to be between 600° to 750° when I pour the gold into it.  I know jewelers who like to heat their ingot molds in a kiln, but I prefer my torch. 

 

4.  As I mentioned, the crucible should also be preheated.  You can’t tell from this picture, but the crucible is glowing red hot.  The reason for this is that gold becomes an oxygen absorber when it’s being heated.  You want to minimize the amount of time that the gold takes to melt, so you shouldn’t waste time by trying to heat a cold crucible along with the metal.  In this picture I am spooning on a thick layer of borax.  The borax will absorb the free oxygen during the melt and protect the fragile gold.

 

5.  The flame in the picture is a neutral flame.  A neutral flame is characterized by the deep blue color at the torch that becomes light blue at its cone, the tip.  Away from the torch the flame is full and feathery.  This type of flame is said to be balanced and will consume all of the oxygen coming through the torch.  It actually protects the molten metal from oxygen attack. For just a second, I have moved the flame away from the metal so that you can see that it is clean and shiny.  It is surrounded by a pool of liquid borax.  If a slag or debris film is present then I would pour off the contaminated borax and apply a new, clean layer.  This would be repeated until the metal shows clean.

 

6.   When the metal is fully liquid I will pour off as much of the borax as I can, then pour the gold into the ingot mold.  The metal should be poured through the flame and the flame is kept on the metal after the pour.  Over a period of a minute I gradually reduce the oxygen until the flame is straight gas, then I shut down the torch.  By slowly cooling the metal I am trying to set up a medium size grain structure that will make the gold easier to forge.

 

7.  My gold ingot has spent the last hour in a pickle pot and then an ultrasonic cleaner.  Here I’m brushing the ingot with a scotch-bright pad to make sure it is clean and free from any borax deposits.  I do not want to roll out my metal until it is clean.  If I rolled dirty metal then I would be forcing contaminates down into the metal.

 

 

Something Old - Something New continued