Jonathan Kaplan on sat 7 aug 99
In plaster work, separators are referred to as parting compounds. These
materials can be used to separate plaster from plaster, rubber from
plaster, etc. etc. and are integral in moldmaking.
There are also sealers, that can be used to seal a model made of pourous
materials such as wood or plaster.
There are many types of available parting compounds. I've used most of them
ranging from Fels Naptha soap, Murphys Oil Soap, etc etc. One needs to be
careful about left residue on the plaster, especially when susequent
castings might be taken. Never ever use Vaseline.
The best all around parting compound is PUP, or Polyurethane Parting
Compound, available from Permaflex Mold Company (614) 252 8034 (800) 736
6653. Many master mold makers including myself have used this material for
years.
Sometimes, there are areas in a casting mold that don't release well, are
slow to release, or need some help. This situation can be easily rectified
by dusting the mold surface with talc. Take an old sock, fill it halfway
with talc, put a rubber band around the open end, and pounce the sock
releasing a fine almost invisible layer of talc on the offending surface.
This is an old moldmakers trick that has been around for ages.
I've fired all sorts of kilns with all sorts of shelf configurations. We
use 3 posts per shelf and over lap the two posts on the outer edges with
the next shelf. This results in a huge firing area. We use 14" x 28"
shelves in both our production gas car kiln and production electric kiln.
Our current shelves are from Spinx (Holland) and Acme Marls(England) and
are still flat after many many years of hard work. In our round type
electric kilns, we use the same posting configuration. BTW, we have always
placed a small wad of EPK/Alumina Hydratre mixture wadding on top of each
most to level each course of shelves. My observation is that the shelves
are more prone to staying flat whereas the posts begin to round and rock
earlier than the shelves. The wadding makes everything more rigid.
Also, in all the years of making pots, I have never washed my shelves. We
do have about six that are washed that we use for classes, but the
remainder of our shelves have been unwashed for years. I have also found
that the cordierite shelves we use have stayed flat longer then their
comparable sized Silicon Carbide shelves. I have not used the
re-crystalized SiC shelves, the thin ones, so I can't comment. Our first
load of Spinx shelves were purchased in the 1982 are are still flat and
still in use.
Plate setters are available in many sizes and configurations and sold by
many supply houses. We use Gimson/Diamond/Norton VB setters in many
diameters and heights. These are incredibly useful for our tableware
production. We use them both in the electrics and gas kilns.
Foundry Hill Creme is indeed from Spinks Clay in Paris Tenn, and is a
wonderful airfloated light firing ball clay. Many years ago it was known as
Gizmo. We use FHC and OM-4 for each other. I like FHC because the LOI is
less. Spinks also has a clay data book that they will send you with all
sorts of info, including a nice piece of their efforts not only as miner os
clay but as partners with the reclaiming of the mined areas. Not to sound
overly warm and fuzzy, but this is very important and I am glad that there
are many companies like Spinks that work in partnership with the Earth.
Hope you are all having a great summer!!!
Jonathan
Jonathan Kaplan, president
Ceramic Design Group LTd/Production Services
PO Box 775112
Steamboat Springs, CO 80477
(970) 879-9139 voice and fax
http://www.sni.net/ceramicdesign
UPS: 1280 13th St. Unit13
Steamboat Springs, CO 80487
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