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.

Above: Box, atnifreeze/water, Gelatin, Mixture poured into the box

Attendance: Rick , Jim Hiltz, Miles, Jim MacLean Paul

We started work on the mold and casting project.
Small boxes were made to accommodate the piece to be duplicated.
Leo explained that the boxes are made a little larger than the piece and a bottom is nailed on.

(Secure the bottom well: Paul's leaked the Gelatin , which made a mess!)

Shellac is applied to seal the wood.

The Gelatin is made by mixing:

Antifreeze (Ethylene glycol) 1:1 with water and heated in a pan of water. An equal volume of Gelatin is stirred in.
When the mixture is warm, it is poured into the box containing the work piece and let cool

A parting agent is needed- i.e. some sort of material to prevent the object from sticking to the gelatine.
We used wax-brushed on the wooden box before adding the Gelatin

Once the Gel sets the piece can be removed and then the agent you use poured into the gelatine mold
One can use plaster, cement, powdered bronze, epoxy mixed with brass or aluminum.

If it is not used quickly, this mold will shrink as water evaporates.

Rick, Miles, Jim MacLean, Jim Hiltz, Paul, Robert

The members brought in the Wood burl pieces for the CBU exhibit.
They will be displayed for the next month at the Gallery

Leo discussed the art of mold making and we agreed to start a project to make an open mold.
He went over the basic principals involved and demonstrated some to the media to be used: rubber, gelatine, cement

We will each bring in a shape and start the process next workshop