Exposure Through Sanding

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When water is added to the dry mix, it turns into a paste and has the same consistency as ready-mix joint compound (mud). From this point forward, the mud is applied to drywall seams and used in the same fashion.

When two or more sheets of drywall are nailed to studs, a seam or gap is created. In order to fill this gap, mud is applied. This produces a smooth, continuous wall ready to paint. The process of filling the joints is often called "mudding." In this process, as many as three or more layers of joint compound (mud) are applied and sanded.

The first step in the drywall finishing process is to apply mud to the seams. Using a six inch mud knife, the worker lays down a bed of mud and completely fills the seams between two adjoining sheets of drywall.

Before the mud dries, a strip of paper (tape) is laid on top of the wet mud and covered with another thin layer of mud. When this layer is dry, it is sanded and the seam is ready for another layer of joint compound.

Typically, joint compound is sanded by hand with either a hand held sanding block or if the work is conducted overhead, a pole sander. Hand sanding requires the worker to be no further than an arm's length away from the wall, where large amounts of dust are generated when the excess joint compound is removed.

Overhead sanding is equally as dangerous, because gravity causes the asbestos-laden dust to fall down onto the worker's head.

When sheets of drywall are hung, they are nailed to the studs of the wall. To ensure a smooth surface, nails are covered with a layer of mud. Since drywall is relatively soft, this is accomplished by over-driving the nail slightly below the surface of the drywall to create a dimple. The small depression in the drywall is covered with mud and sanded. Similar to finishing seams of drywall, exposure to asbestos from this procedure occurs when the mud is mixed and sanded.

After the first coat of mud dries, three or four additional coats of mud are applied to drywall seams with progressively larger mudding knives.

After the taping phase is finished, three or four additional coats of joint compound are applied with progressively larger mudding knives, and sanded between each coat. Every time the dry joint compound is sanded, more asbestos is released into the breathing zone of the worker.

Each coat of mud is sanded when it dries. Every time the dry joint compound is sanded, more asbestos is released into the breathing zone of the worker.

After three or four coats of joint compound are applied and sanded, the wall is ready for primer and paint.