A plaster trowel is a tool specifically designed to apply plaster, a substance composed of gypsum and lime, to a surface. Plaster provides a durable coating over such materials as wood, stone or brick which can then be painted over. Using a plastering towel to apply plaster yourself saves the cost of paying a service to do the work. Plastering trowels are not difficult to use, but they require a certain technique and must be kept moistened while in use.
Place a tarp or plastic sheet on the floor around the area you intend to plaster. The covering will catch any spills and make cleanup easier.
Locate an object or area with a flat abrasive surface. Rub the plaster trowel's edges, mimicking the motion used when applying plaster, against the surface. This technique will prep the trowel for actual plastering use.
Wet down the trowel blade with a wet rag. Prepare the veneer plaster or other plaster compound according to the manufacturer's directions in a bucket. Transfer some of the plaster onto a hawk. Use the plastering trowel to scoop up the plaster out of the hawk.
Hold the plaster trowel so it is positioned on the same side of the shoulder of the arm you are using to hold the trowel. Apply the plaster in a 3/8-inch-thick layer on the surface with the plaster trowel. Use a technique that mimics the back-and-forth motion of a paint brush to apply the plaster. Allow the coat 24 hours to dry.
Prepare a new batch of plaster and prep the plaster trowel using the steps outlined above. Apply the plaster to the surface, starting by positioning the plaster trowel perpendicular to the surface and then slowly lowering the trowel until it is flat against the surface as you move forward. Repeat this technique until the surface is covered with plaster. Allow the second coat 24 hours to dry.
Always keep the plaster trowel, including the blade and handle, clean when not in use. Wipe it off with a clean cloth if left unused for a few minutes or longer.
Refrain from leaving the plaster trowel positioned on its side. The exposed edges of the plaster trowel can cause injury if someone comes into contact with it.