Lightweight Hydrocal®* Plaster - 1/2 gal

A plaster that hardens fast and weighs little

Terrain on a layout is built in two goes: first a framework arises from polystyrene, strips of cardboard or wire mesh and only then comes the layer that holds the shape and can be worked. This material is intended precisely for that second phase. Compared with an ordinary building plaster it is lightened, so a large board does not turn into a piece that cannot be carried once it is covered, and at the same time it hardens into a firm shell that will stand trimming with a knife, sanding and the drilling of holes for trees.

Rock castings and how to handle them

The second main use is casting into rubber molds. The mixed mass is poured into a mold, once it has set the casting is tipped out and it is laid onto a slope while still damp, as long as it can be broken off further and pressed into the base. A dry casting is hard and breaks irregularly, which suits a rock that is meant to look fissured, but it is harder to join it to the neighboring piece. The joints between castings are filled with the remainder of the same mass and gone over with a damp brush.

Coloring takes place on a damp surface. Plaster draws in like blotting paper, so thinned paints soak into it and create natural transitions instead of marks. It is always mixed by sprinkling into water, never the other way round, and only as much as can be worked, because once the mass starts to thicken it can no longer be brought back by adding water. The remainder in a container never belongs down a drain, where it sets.

Remains stuck to tools disappear easily as long as they are damp. Anyone mixing in a container of soft plastic will, by flexing its walls after curing, tip the broken-off cake out in one piece and use the container again. Unused powder belongs in a resealable container, because it takes up airborne moisture even closed in a sack and starts to form lumps.