Red Top Cover Coat Finish Plaster / Red Top Firecode Plaster / Structolite Plaster

Manufacturer: United States Gypsum Company (USG) Years Produced: 1940–1977 Asbestos Type: Chrysotile

Product Description

Red Top Cover Coat Finish Plaster, Red Top Firecode Plaster, and Structolite Plaster were gypsum-based building materials manufactured by United States Gypsum Company (USG), one of the largest and most widely recognized producers of construction materials in North America. These products were distributed under the “Red Top” brand name, a well-established USG product line, alongside the Structolite designation for a lightweight base-coat plaster formulation.

These plasters served distinct but related purposes in mid-twentieth century construction. Red Top Cover Coat Finish Plaster was applied as a smooth, durable finish layer over base coats on interior walls and ceilings. Red Top Firecode Plaster was engineered specifically for fire-resistive assemblies, commonly used in commercial buildings, hospitals, schools, and multi-unit residential structures where building codes mandated fire-rated construction. Structolite Plaster, a perlite-aggregate base coat, was used beneath finish plasters to provide bulk, insulation, and a surface suitable for finish coats to bond to.

All three products were staples of the plastering trade during their decades of production. They were sold in paper bags and distributed nationally through building supply dealers and gypsum specialty distributors. These materials were used extensively from the post-World War II construction boom through the mid-1970s, appearing in both residential and large-scale commercial and institutional projects across the United States.

Asbestos Content

Litigation records document that Red Top Cover Coat Finish Plaster, Red Top Firecode Plaster, and Structolite Plaster contained chrysotile asbestos as a formulation component during portions of their production years spanning approximately 1940 through 1977. Chrysotile, often referred to as white asbestos, is a serpentine fiber that was widely incorporated into gypsum plaster products during this era for its reinforcing properties, its ability to improve workability, and its contribution to fire-resistance ratings.

Plaintiffs alleged that USG incorporated asbestos into these plaster formulations without adequate warning to the workers who regularly mixed, applied, and sanded these products. Internal industry documentation, as developed through discovery in asbestos litigation, has been cited to demonstrate that manufacturers including USG had access to information regarding the health hazards of asbestos fiber inhalation well before warnings were placed on product packaging or before reformulation occurred.

The Firecode designation is particularly significant from a liability standpoint, as plaintiffs alleged that fire-resistive plasters often contained elevated proportions of asbestos relative to standard finish plasters, given asbestos fiber’s well-documented heat-resistant properties. Structolite’s perlite-aggregate base coat formulation was also alleged to have incorporated chrysotile during this period, exposing workers during mixing and application to airborne fiber release.

How Workers Were Exposed

Workers most directly affected by these products were those involved in the plastering trades and construction generally. Plasterers, lathers, drywall finishers, and general laborers working on job sites where these USG products were in use faced repeated and often prolonged occupational exposures to airborne asbestos fibers.

The nature of plaster application created significant opportunities for fiber release. Dry plaster products were typically sold in powdered or semi-powdered form requiring on-site mixing with water. The act of opening bags, pouring product, and mixing generated substantial dust, and chrysotile fibers became airborne during this process. Application itself — troweling, floating, and feathering plaster across wall and ceiling surfaces — could further disturb fiber-containing material. Sanding or abrading dried plaster coats during finishing or repair work is documented as among the most fiber-releasing activities associated with asbestos-containing plasters.

Litigation records document that industrial workers generally, including those in construction, renovation, and building maintenance occupations, experienced bystander and direct exposure. Workers in adjacent trades — electricians, pipefitters, painters, and general laborers — working in the same enclosed spaces as plasterers were also alleged to have been exposed to asbestos fibers released by these products without being the direct applicators.

Ventilation on construction sites during the mid-twentieth century was frequently inadequate, and respiratory protection for plastering trades workers was rarely provided or required prior to the development of modern occupational health standards. OSHA’s first permissible exposure limits for asbestos were not promulgated until 1971, and even those early standards were revised significantly downward in subsequent decades as understanding of chrysotile’s carcinogenic potential developed. Workers using Red Top and Structolite products during the 1940s through the early 1970s therefore had little or no regulatory protection during much of the period these products were in active use.