Step 3: The Slurry

The next step involves making a strong silica based shell around the wax sprue. After coating the wax with floor wax, I dip the whole sprue into the silica based slurry and then coat it with a silica based sand. The first 3 dips are coated with a very fine sand so that the details and texture of my piece are molded. The next 5 dips use a coarse sand so that the shell is strong. The last dip uses no sand. Each dip requires 6-8 hours to dry before it can be dipped again. The shell is hard, brittle, and has the negative mold of my piece.
In the middle picture, the sprue has only one dip completed. In the other two pictures, the same sprue has been dipped all 9 times.