USG HYDROCAL Gypsum Cements Sealers and Parting Compounds - Manual (Page 2)

Removal of Gypsum Cast When gypsum cement has set on a properly sealed and separated surface, the model can be removed by one or more of the
following methods:
1. Wedge evenly around surface with wedges or a sharp tool.
2. Use compressed air gently to separate.
3. Suspend piece so the weight of the mold, aided by light tapping, performs the separation.
4. In extreme cases, soak the cast and its pattern in warm water for a short time. Then apply one or more of the above tech-
niques. Careful use of a compressed-air jet at a corner or convenient edge may be necessary to start release.
Casts should always be completely set before removal is attempted. When molds or patterns of most flexible molding com-
pounds are used to form the gypsum cement, no separator is necessary and removal of the set object is simplified. An excep-
tion to this is the glue or gelatin mold, on which a parting compound must be used.
General Recommendations Efflorescence (a crusty appearance on the model surface) may result if models, patterns or molds are made of H YDROCAL ® Brand
A-11, H YDROCAL Brand B-11, U LTRACAL ® -30 or other gypsum cements or plasters and are dried slowly under conditions of mod-
erate or high relative humidity.
To prevent efflorescence, apply one of the following products to the model or mold surface. Use one or more coats.
Valite II —Can be used on a wet surface. Must be thoroughly stirred before using. Available from PSH Industries, 5346 East
Avenue, Countryside, IL 60525.
Patterns and models should be made hollow wherever possible to facilitate drying and minimize possibility of efflorescence.
When aluminum and magnesium patterns and molds are used in conjunction with H
YDROCAL Brand A-11, H YDROCAL Brand
B-11 and H YDROSTONE ® Cement, special care is necessary to prevent a metal-gypsum cement reaction. In these instances the
metal must be carefully painted with a thin coat of cut shellac or clear lacquer and a separator needs to be applied. Failure to
prevent contact between metal and gypsum cement will result in bubbles on the face of the H
YDROCAL cast and a pitted surface
on the metal.
Health and Safety Information
WARNING: When mixed with water, this
material hardens and then slowly
becomes hot. DO NOT attempt to make a
cast enclosing any part of the body using
this material. Failure to follow these
instructions can cause severe burns that
may require surgical removal of affected
tissue. Avoid dust. Dust may cause irrita-
tion to the eyes, skin, nose, throat, or
upper respiratory system. Wear eye and
respiratory protection to avoid irritation.
Product safety information:
(800) 507-8899.
Trademarks:
The following trademarks used herein are
owned by United States Gypsum
Company: E
POXICAL , H YDROCAL , U LTRACAL ,
H YDROSTONE , and USG.
Note
We shall not be liable for incidental and
consequential damages, directly or indi-
rectly sustained, nor for any loss caused
by application of these goods not in
accordance with current printed instruc-
tions or for other than the intended use.
Our liability is expressly limited to
replacement of defective goods. Any
claim shall be deemed waived unless
made in writing to us within thirty (30)
days from date it was or reasonably
should have been discovered.
125 South Franklin Street
P.O. Box 806278
Chicago, IL 60680-4124
A subsidiary of USG Corporation 800 USG.4YOU (874-4968)
http://www.usg.com © 2000, United States Gypsum Company
IG515/rev. 8-00 Printed in U.S.A. United States Gypsum Company