More Dopping Tips
Stephen W. Attaway, Ph.D.
I want to share some more tips that may improve dopping. I like to use Super Glue for the initial dopping, then I transfer with two-part epoxy. I use a transfer block to hold the dop.
For the transfer, I have found two methods that work well for me. As
Merrill said, mix your epoxies well. Only a small amount of epoxy is needed,
but you will need to use a larger amount to get a good mix.
Be very careful to spread a uniform coat of epoxy around your stone. Epoxy shrinks as it cures. To realize how much force can be generated when epoxy sets, try putting some in a test tube. As the epoxy sets, the polymer will contract and initiate enough stress in the test tube to break it.
When we first began transferring our stones with epoxy, some of the stones would not be aligned correctly. The stones would tip during the transfer, and the girdle would not be level. At first, we thought that our transfer block was at fault, then we tried to blame the dops. We discovered that laying the transfer block on its side caused a small drop of epoxy to form on one side of the stone. The shrinkage of the epoxy was uneven, resulting in the stone being pulled to the side having the most glue. Now, we make sure that the glue is uniform all around the stone.
We all know how water can break things as it freezes. Epoxy can do the same thing. For bigger stones, the shrinkage forces become very large. In some cases, the culet is at risk of being ‘pulled’ off the stone. When transferring large stones, I always try to make sure that the culet is free of epoxy. You can use wax to protect the culet.
To remove the super glue, heat can be used. We place the transfer block in the oven and heat it to 200 degrees F. The heat will decompose the super glue and set the epoxy. Since the epoxy will be rubbery when hot, you must allow both the stone and the transfer block to cool at room temperature before removing it from the oven.
For stones that are heat sensitive, I let the epoxy set at room temperature
overnight. I then coat the epoxy with wax and place the dops in a test
tube half filled with acetone. The acetone is such a strong solvent for
super glue that the stone does not need to be submerged. Just the vapors
will dissolve the super glue in a matter of hours. You will have to be
very careful to make sure that a good coating of wax covers the epoxy,
otherwise it will soften.