This gorgeous shell was cast in solid silver from a mussel shell - using a lost wax casting method, then the magic happens! A layer of solid gold is carefully heat-applied to the silver, then an iridescent patina is applied to mimic the outside of the shell.
read on for more details ....
Pronounced - 'cum boo', this is an ancient Korean technique and literally means 'attached gold'.
It is nothing like gold-plating or gilt using gold leaf - this method actually bonds the gold and silver metals permanently together.
Of course, it is all in the preparation. The 24 carat gold foil can be sourced, but is very fine and great care is needed to ensure it is not creased or wasted.
The silver shell itself needs to be prepped, as the gold will only attach to pure metal - not sterling silver. We need to use sterling silver for affordability and durability, and the pure 'fine' silver is coaxed to the surface by repeatedly heating, thereby burning off the copper in the sterling silver. You see the shell is now a fine white color - that's perfect!
The gold bonds at a high temperature and when pressure is added, this causes an electron exchange at the surface between the two metals, creating a permanent diffusion bond.
I use a hot plate to heat the pre-prepared shell, then carefully and gently lay the foil over the area. The tricky bit is to brush it into the curves and crannies of the shell, then burnish it into the bond with an agate tool.
It's hot work as you have to keep the temperature high! and the burnishing needs to be both delicate, so it doesn't scratch or tear, and forceful to ensure good bonding pressure.
Phew!! But the results are magic!
You have to be a witch to stir up this black brew! The theory is simple - silver oxidizes and turns black with the application of liver of sulfur.
First cleanliness and a burnished surface is essential to achieve a permanent finish. Then the clever part is in getting the l.o.s brew just the right temperature, and strength and adding witchy ingredients like salt and ammonia to get exactly the right iridescent shade.
I love that it mimics the natural glistening black of the mussel shell!