Joint compound

In North America, troweling joint mud on gypsum panels is a standard construction technique prior to painting wall and ceiling surfaces.

The compound is a complex combination often including water, limestone, expanded perlite, ethylene-vinyl acetate polymer, attapulgite, and other ingredients.

This type of joint compound is commonly referred to as "hot mud" due to the exothermic reaction that takes place when the powder is mixed with water.

Setting-type joint compounds are plaster of paris based and harden by chemical processes and evaporation rather than solely evaporation, giving it an advantage in filling holes and gaps that would take many days to dry out with shrinkage cracks if using the drying type compound.

[11][12] Drywall systems without penetrations can obtain ASTM C475 fire ratings using conventional joint compound at the seams.

Applying and sanding joint compound is messy work, and finished surfaces, such as floors and air handling ducts, must be covered.

Construction workers mixing or sanding drywall joint compound are often exposed to high concentrations of dusts containing talc, calcite, mica, gypsum, and in some cases, respirable silica;[17] which have been associated with varying degrees of immediate eye, nose, throat, and respiratory tract irritation.

When silica is present in the drywall joint compound, workers may also face an increased risk of silicosis and lung cancer.

In 1977 the Consumer Products Safety Commission banned wall patching (joint) compounds containing asbestos.

[21] For the reasons above and possibly others, constant use of a respirator is recommended by almost all drywall compound manufacturers and is required by some labor authorities.