A: This isn’t a plaster so much as a system, the ingredients for which can be assembled from various manufacturers. It consists of a gypsum plaster modified (hence the abbreviation M. G., for Modified Gypsum) by the addition or plastics. The system involves mixing precise amounts of several products, including Hydrocal FGR-95 from USG or alternatively, Densite HS from Geogia Pacific—both are gypsum-based cements; dry melamine resin powder; a hardener—I think it is ammonium sulphate; and a liquid polymer-Forton VF-812. These various ingredients are the base to which aggregates, fiberglass, colorants and metallic powders may be added; which latter, though expensive, give the effect of metal rather well. For complete instructions refer to the suppliers.

One word of warning—the dry melamine resin powder is extremely hydroscopic; it will form hard lumps on exposure to atmospheric humidity, don’t leave it open, and screen the mix to remove lumps that may have formed. It makes a rather syrupy mix that is sticky when wet and tenacious when dry, although it takes a couple of days to set properly. It is usually most economical to get the gypsum material from your local USG distributor, and send away for the other ingredients.