The following are some pictures showing how I made some cast glass rocks as part of my work with glass. The pictures are in

reverse order and for several different rocks.

This is an uncleaned rock after the plaster and sand investment was chipped off, the investment was fairly week after firing

so easily chipped off with and old screwdriver

This picture was taken in the kiln straight after the firing was complete, you can see the glass has mostly gone from the funnel

on top of the rock. The glass doesn't flow very well unless there is some pressure behind it so there is a layer about 2mm to 5mm

thick on the side walls of the funnel which did not run down.

The uncleaned rock sitting on top of the investment which was chipped off.

This is the wax rocks and funnels covered with several coats of plaster of paris and playground sand mixed in a 50/50 ratio

placed over the special plaster and silica flower first layer.

I found i couldn't put on about more than a 5mm layer at a time or it might crack when drying.

This is the wax rocks and funnels covered in their first coat of a special plaster and silica sand mixture. This fine silica flower

mix give a very good copy of the was surface due to the fine particles.

The wax funnel can be seen on top of the wax rock here, the rock is hollow to use less wax and reduces the amount of

shrinkage as the wax cools. This funnel will be filled with glass as can be seen in previous pictures and will meld down into

mold cavity below.