Plaster cloth is a relatively recent innovation in model railroad scenery construction materials. It was originally made as a sterile product that doctors used to make casts after they set broken bones. Sculptors began using plaster cloth in their artistic work, and it didn’t take long for modelers to discover this medium was useful as a scenery base.
Plaster cloth consists of a porous, loosely woven gauze impregnated with a thin layer of dry fast-setting plaster of Paris. The dry material comes in rolls and can easily be cut into manageable pieces with a pair of scissors. Dipping the plaster cloth into a pan of warm water activates the plaster while the gauze holds it together as the wet piece is lifted and applied over a supporting base. This makes the plaster cloth somewhat cleaner to use than the typical toweling dipped in plaster that’s often used to make a scenery base.
There are many sources of plaster cloth. Most model railroad hobby dealers carry the popular Woodland Scenics line of scenery products that includes the firm’s plaster cloth. Walthers also sells similar products made by Faller, Noch, and Scenic Express. Many other brands of the material are sold by most craft hobby stores and art supply shops. These other sources sell the plaster cloth in a variety of different roll sizes, including bulk packages.
Applying the plaster cloth is an easy 2-step process. First, some sort of structure is necessary to support the wet plaster shell as it is applied. Hills can be made of shaped Styrofoam, wood formers covered with screen wire, or strips of cardboard and masking tape. On flat surfaces, wads of newspaper or packing peanuts can be piled up and secured with masking tape to create a hill shape. Once the supporting structure is ready, it’s time to apply the plaster cloth.
Cover the track and turnouts to protect them from drips of plaster. Then unroll the plaster cloth and cut the entire strip into pieces that are roughly square. Dip one piece into a pan of warm water and drape it onto the supporting structure. Repeat the process as needed, overlapping the pieces to gain thickness and strength. Use a wet paintbrush to blend the edges and create a smooth surface, but don’t spend a lot of time on blending, as the plaster sets up quickly. It’s best to build up several layers of gauze over the entire structure and allow it to harden.
The photo above shows a trick that reduces the mess of modifications. Apply pieces of dry plaster cloth wherever any repairs may be needed. If necessary, they can be temporarily pinned in place. Then use a spray bottle filled with warm water and a few drops of detergent to serve as a wetting agent, and saturate the cloth to activate the plaster.
Once the initial shell has hardened it’ll be quite stiff, but many modelers take the extra step of reinforcing it with a top layer of regular molding plaster or U.S. Gypsum Gypsolite rough-coat house plaster. After the reinforcement layer is applied and set hard, it’s a good idea to remove the wadded up newspaper and temporary cardboard supporting structure. Otherwise it will absorb moisture and begin to smell over time. At this point, the hard surface is ready for finishing with the usual rock detailing, ground cover, and foliage.