Acoustical Plastering System

Acoustical plastering is often used in commercial interiors in order to achieve a seamless appearance with high noise reduction coefficient (NRC). Due to its low impact resistance, it is typically only used for ceiling and upper wall applications. These plasters can be based on gypsum, portland cement, or finely crushed mineral aggregates such as recycled marble and glass. The aggregates lend porosity to the plaster and allow sound waves to pass through. The sound waves are absorbed by the backing, commonly made from mineral wool, and are converted into heat. Acoustical plaster systems can be used on suspended ceilings or applied directly to a hard substrate with adhesive or screws. The plaster itself may be spray-applied or troweled onto the mineral fiber backing. The backing may be supplied pre-coated with a base coat of plaster to which a finish coat of plaster is applied, or it may be supplied uncoated. Some products include an additional layer of gypsum board between the mineral wool and plaster. 

This Common Product describes an acoustical plaster system composed of a mineral wool backing adhered to a substrate with an adhesive that is supplied as a powder and mixed with water on-site. The plaster component is summarized as a single coat of acoustical plaster based on crushed limestone or marble. Plasters are often applied in multiple coats, with some variability in content between base coats and finish coats, but disclosure documents often report content at the system level, so content in the base and finish layers were combined for simplicity. Additional system components such as primers were beyond the scope of this Common Product, and can add additional hazards not considered here.