Like spackle, wood fiber plaster is used to fill cracks and holes prior to staining. It has been, and continues to be widely used by carpenters and others in the construction industry. One such product used by many woodworkers prior to 1978 was RED TOP Wood Fiber Plaster, marketed by the United States Gypsum Company.
Up until the 1980s, the various types of wood fiber plaster that were available for woodworking and finishing projects contained calcified gypsum (a substance similar to chalk), cellulose fibers from actual wood and asbestos. The asbestos – primarily “brown” asbestos, or amosite – was added to increase the tensile strength of the plaster as well as making it flame retardant.
Once applied and allowed to harden and dry, such wood fiber plaster could be sawn, drilled, nailed and sanded just like real wood. The difference is that these activities released millions of microscopic, needle-like fibers that once taken into the lungs would burrow through the lung tissues from the inside emerging into the pleural layers on the surface of the lungs and inner chest wall. During this process, these hard fibers interact with cellular DNA in ways that medical science has yet to determine, causing them to become cancerous and resulting in mesothelioma.
The wood fiber plaster that is manufactured, marketed and used today does not contain asbestos: the most common strengthening agent is synthetic resin. However, asbestos-containing wood fiber plaster may be present in older homes built prior to the mid 1980s. If the walls of the building are in good condition and have a solid coat of paint, it is likely that such plaster embedded in the walls has thoroughly dried and is therefore not friable – meaning that the best course of action is to leave it be.
Unfortunately, there is no reliable way to determine whether or not a damaged wall is releasing asbestos fibers through a visual inspection. It requires the testing of an actual air sample by a professional laboratory.
Those who have been harmed by an asbestos-containing wood fiber plaster product in the past should also know that USG Corporation, formed in 1985, is the parent company of many smaller companies that manufactured such materials. Although USG representatives state that the parent corporation itself never manufactured nor sold these materials directly, it is still important to understand when considering legal action. A corporation that assumes control over a smaller company may also assume that company’s liabilities.