Forton MG Plaster

Q: What is this Forton MG plaster you mentioned, and where do you get it?

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.

by Andrew Werby