Attendance: Rick Jim Hiltz, Jim Maclean, Paul, Miles, Robert


Work continued on the mold project.

Paul  and Jimmy Maclean had a mold blank ready. The Gelatin did shrink as Leo predicted.

A compound of Medussa cement and fine stone was mixed with a few dollops of Concrete bond and then small amounts of water added to produce a thick product.  It is important to add small amounts of water gradually as too much water will spoil the mixture. This was poured into the mold and let set. The settling can be aided by using a sander under the mold box, tapping the box down on a solid base and then screeding the surface to get it smooth: the same process as when making a concrete slab.

Tip: the slower that concrete cures ( i.e. the slower that the water evaporates) the harder the finished product. Leo instructed us to wrap the pieces in plastic to slow the curing.

Leo says that , in place of Gelatin, one can use silicone to make the mold-the same silicone one uses for bathtub sealing. It hardens well and does not shrink.

Use Isopropanol as a parting agent. Coat the materials with this to ease separation of the pieces.
This is Rubbing alcohol : C3H8O is the chemical formula (Can also be written as : (CH3)2 CHOH)
http://www.ivyroses.com/Chemistry/Organic/Naming-Alcohols.php

Powdered brass, copper, aluminum can be used for the mold instead of concrete. Epoxy works as well.

Leo produced several examples of small items of art  that were done from these powdered metals.

We agreed to meet Friday evening at the Art exhibit at UCB.