Product Review: Pyrok

What does the abbreviation “NRC” mean to you? To acousticians it usually means Noise Reduction Coefficient, a single number rating for the absorptive characteristics of a specific material AND mounting condition at four frequencies within the range of speech. It is not, as its name implies, the difference in sound levels between two conditions or between rooms. The NRC is important in designing spaces for improved acoustic environments that enable people to better concentrate on their tasks.

Ratings range from 0.00 (a very thick concrete wall) to 1.00 which is equal to an open window. The higher the rating, the more absorbent the material/mounting condition. Some common building materials have the following NRC ratings:

-Gypsum wall board (0.05)
-1 inch thick acoustical panels (0.75-0.80)
-“El cheapo” ceiling tile (0.50)
-The ceiling tile we typically call for (0.95)

Pyrok Acoustement is an acoustical plaster spray applied by licensed applicators. It is available in three different product types: two for interior applications that vary in durability and absorption (0.50 NRC at half-inch thick application to 0.65 NRC at one-inch thick application) and one for wet, humid or acidic conditions (0.60 NRC at one-inch thick application).

We think well of this lesser known “green” product because of its high acoustical performance and ability to adhere to a variety of substrates including drywall, concrete, cement, and metal. It also adds a decorative appearance with a spray texture or a semi-smooth, troweled finish. Available in 12 custom color tints, it can also be painted with spray-applied, water-based paint. We used this product in the lobby of Thorburn Associates’ new offices in Raleigh-Durham. If you’re in the area, we invite you to stop by for a look and listen. More info: