Zonolite Spra-Insulation / MK-1 / MK-2 / Spraytex / Spra-Text / Z-Tex

Manufacturer: W.R. Grace & Co. Product Category: Spray-Applied Fireproofing Years Produced: 1958–1973 Asbestos Type: Chrysotile Trust Fund: W.R. Grace & Co. Asbestos PI Trust

Product Description

Between 1958 and 1973, W.R. Grace & Co. manufactured and marketed a family of spray-applied fireproofing and insulation products under several closely related trade names: Zonolite Spra-Insulation, MK-1, MK-2, Spraytex, Spra-Text, and Z-Tex. Although these products were sold under different labels at different points during the fifteen-year production period, they shared a common purpose and a common composition: they were designed to be mixed with water and sprayed directly onto structural steel, concrete decking, and other building substrates to provide fire resistance and thermal insulation.

These products were used extensively in commercial and industrial construction during the postwar building boom, appearing in office towers, manufacturing facilities, warehouses, schools, hospitals, and government buildings across the United States. W.R. Grace promoted them as efficient, cost-effective alternatives to traditional enclosure methods of fireproofing, and contractors adopted them widely because spray application was faster and less labor-intensive than wrapping or encasing structural members by hand.

W.R. Grace was one of the dominant players in the spray-fireproofing market during this era. The Zonolite product line in particular drew on the company’s broader involvement with vermiculite mining and processing, including operations at the now-notorious Libby, Montana, mine — though the chrysotile content in the Spra-Insulation family of products represented a distinct and separately documented hazard.

Asbestos Content

All products in this group — Zonolite Spra-Insulation, MK-1, MK-2, Spraytex, Spra-Text, and Z-Tex — contained chrysotile asbestos as a functional ingredient. Chrysotile, sometimes called “white asbestos,” is a serpentine-form mineral fiber that was widely used in construction materials because of its flexibility, tensile strength, and resistance to heat and flame.

In spray-fireproofing products of this type, chrysotile served as a binder and reinforcing component that helped the sprayed material adhere to surfaces, resist mechanical disturbance, and maintain its structural integrity under high-temperature conditions. The asbestos content in similar spray-applied fireproofing products of the period was typically significant by weight, making these materials among the more heavily loaded asbestos-containing products used in construction.

The AHERA (Asbestos Hazard Emergency Response Act) regulatory framework specifically addresses spray-applied surfacing materials of this type as a category of asbestos-containing material (ACM) requiring professional inspection, management, and abatement in buildings where they are present. Applied surfaces from this product family that remain in older buildings today are subject to AHERA requirements and, depending on their condition, may require encapsulation or removal by licensed abatement contractors.

How Workers Were Exposed

Workers in the industrial and construction trades were exposed to asbestos fibers from these W.R. Grace spray-fireproofing products through multiple pathways over the production years of 1958 to 1973.

During Application: The spray-application process was among the most hazardous exposure scenarios associated with these products. Workers who mixed the dry product with water and operated spray equipment worked in close proximity to the point of application, where airborne fiber concentrations could reach levels far exceeding what is now understood to be safe. Spray nozzle operators, hose handlers, and finishing workers were all in the immediate exposure zone.

Bystander and Adjacent Trade Exposure: Fireproofing application in active construction sites meant that ironworkers, electricians, plumbers, sheet metal workers, and other tradespeople working in the same areas were exposed to airborne fibers even when they were not directly handling the product. Overspray, air circulation, and the general dusty environment of construction sites distributed fibers beyond the immediate application area.

Disturbance and Maintenance: Once applied, these spray-fireproofing materials remained in buildings for decades. Subsequent trades who cut, drilled, sanded, or otherwise disturbed the cured coating during renovation, repair, or demolition work faced secondary exposures that could be equally hazardous. Maintenance workers, electricians running new conduit, and demolition crews have all been documented as exposed populations.

Industrial Facility Workers: Industrial workers generally who were employed in facilities where these products had been applied were also subject to ongoing exposure if the installed material was in poor condition, friable, or subject to mechanical disturbance in the normal course of operations.

OSHA’s current permissible exposure limit (PEL) for asbestos is 0.1 fibers per cubic centimeter of air as an eight-hour time-weighted average, with an excursion limit of 1.0 f/cc over a 30-minute period. These regulatory thresholds did not exist during most or all of the production period for these products, and workers of that era had no regulatory protection and little or no warning from the manufacturer about the hazards they faced.