Ceramic Design Group on sat 13 apr 02
Just to add to this thread and to lessen the confusion:
US Gypsum and Georgia Pacific are the primary manufacturers of plaster
products for the ceramics industry.
My years of experience is with USG products.
There are 2 distinct types of gypsum products that they make:
There is 1. Plaster and there is 2. Gypsum Cements and briefly.......
Pottery plaster #1, Puritan, Moulding Plaster, etc are plasters. They are
designed to be used at higher consistencies, which is the water to plaster
ratio. These have a high degree of absorbancy, larger expansions, and are
used for purposes used as slip casting molds, carving, etc. etc. They are
soft type materials. ( pottery #1- 70 parts water to 100 parts plaster)
Ultracal 30, Hydrocal, Hydrostone, Ceramical, etc. etc. are gypsum cements
and are much harder, have a lower expansion, low absorbency (but can be
saturated) and are used for case molds and Ram Dies (Ceramical) and yes,
Hydrobats. Their surface is much harder and they are mixed with a very low
consistancey. Hydrocal is worked at 50 parts of water to 100 parts plaster.
Ultracal 30 is worked at 30 parts of water to 100 parts of plaster.
I have made literally hundreds of bats from Potter #1 plaster. They will
last a lifetime when properly used. You can make many dozens in a day with
some simple procedures.
I have used plaster the duration of my pottery life. I have no fear of it
and when properly understood and used, is a magnificent material used in
many different aopplication in our shop.
I have seen the Hydrobats at NCECA the past few years. They look well made
and the imbedded rubber grommet that secures it to the wheel head pins is
very well thought out.
Jepson Pottery in Florida has a selection of bat molds, wheel head adapters,
etc. that are derived, it seems to me, from the original Randall system that
consisted of a bucket type head, and beautifully turned cast aluminum alloy
bat molds. Jepsons bat molds are now a heavy duty plastic material. Well
designed. I remember the original Randall molds as being quite costly, but
they made beautifully shaped bats. The shape of the Hydrobats and the Jepson
bat systems are certainly derived from the original Randall system.
They seem to all work, and it just becomes a matter of preference to me
which system you like and can afford. THere are also some square bats out
there from North Star, I think, with a wheel head adapter.
We have used bats from Creative Industry, Amaco Brent, as well as our own
double tempered Masonite disks. In fact, My DT Masonite disks are will over
15+ years old and are aging quite well and we use them all the time. For my
production purposes, the DT Masonite disks are my favorite.
Its a matter of preference and cost.
Jonathan
| |
|
