Some of the most common and widely used separators are as follows: Do not react destructively with the plaster or gypsum cement surface, or with the pattern. Spread easily and uniformly in a thin, continuous insoluble film.Ĥ. Satisfactory separation agents must provide the following functions:Ģ. Or model and apply several coats of a clear lacquer. After wood filler has set overnight, apply a coat ofĪ clear acrylic sealer and allow to dry. Apply a heavy coat and let it dull down then wipe off excess byĪcross the grain. Grain of the wood, but should be reduced to a satisfactoryīrushing consistency with the recommended thinner. A paste wood filler can be used to fill the Mahogany patterns or models require special treatment because gypsum cement casts may adhere to undercuts caused by multiple Apply second coat after first coat has thoroughlyĭried.Where a plaster or gypsum cement pattern is used, apply lacquer immediately after set. Lacquer thinner so that the model or pattern readily absorbs the firstĬoat. Correct procedure is to reduce lacquer with Two coats of lacquer provide more resistance to moisture than shellac. Patterns of metal, glass, plastic and other impervious materials normally do not require sealing.Ī quick-drying lacquer applied by brush or spray gun is an excellent sealer for wood, plaster and gypsum-cement patterns and master models. Gypsum cement patterns also require sealing to prevent them from absorbing water from the plaster mix and causing the mix to adhere to the gypsumĬement pattern. Sealing is particularly essential for wood patterns to prevent dampness from causing the wood to swell, resulting in release difficulty. They also permit removal of plaster or gypsum cement from the surface of the pattern or model upon which it “sets up.” Porous model materials require sealing prior to application of the parting compound.Īll porous models, patterns and molds must be sealed before the parting agent is applied. Parting compounds (also called “separators” or “releasers”) are needed to prevent adhesion of plaster or gypsum cement to patterns or models. Or B-11 cements, but higher wet and dry strength is Setting expansion is somewhat greater than with A-11 On “short side” and has a tendency to tear. When formed under a template it is slightly A neutral gypsum cement having a normal set of 25
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