Table Of Contents
Quick Facts About Asbestos Mastics & Construction
  • Years Produced:
    Early 1900s – 1980s
  • Places Used:
    Ships, homes, offices, boilers, furnaces, steel mills, factories
  • Toxicity:
  • Asbestos Use Banned:
  • Friable:

How Were Asbestos Mastics Used in Construction?

Mastic is paste-like cement that is used as an adhesive, sealant and joint-filler. Gunning mix is a type of paste applied to metals, plastics, wood or masonry as a repair compound. It may also be used to smooth pitting, rough surfaces or irregularities that may occur on equipment linings. This mix is usually applied using a caulk gun or similar pump gun, which was also known as an asbestos gun.

Square floor tile with asbestos and trowel marks
Black asbestos mastic is revealed behind an asbestos floor tile.

Construction mastic is used in residential homes or commercial buildings under floor tiles, ceiling tiles, acoustical tiles, roofing, walls and windows. Gunning mix is used to fill in gaps or spaces on the surfaces of steel furnace linings, hulls, storage tanks, sonar domes and pump casings. These products were also called asbestos paste.

After the use of asbestos declined because of health concerns in the 1980s, American companies began using alternatives to asbestos in their construction mastic and gunning mix products. Other countries may still manufacture these materials with asbestos, and there are no permanent regulations preventing them from entering the U.S.

Square ceiling tiles moved to reveal asbestos mastic underneath
Asbestos mastic was also used to secure ceiling tiles.

The U.S. Environmental Protection Agency is currently reviewing new uses of asbestos and placed a temporary ban in 2019 on the manufacture and importation of certain asbestos products, including adhesives such as mastics and gunning mix. It is unknown how long it will take the agency to conduct the review.

Occupations that are at risk of exposure from mastics and gunning mixes include:

  • Steel mill workers
  • Power plant employees
  • Engineers
  • U.S. veterans
  • Shipbuilders
  • Maintenance workers
  • Carpenters
  • Flooring installers

Construction workers who install, remove, repair or perform other maintenance work may have been exposed to asbestos in mastics and gunning mixes. Workers in the factories that produced these products faced occupational asbestos exposure daily.

According to a 2022 report by the European Commission, over 70,000 workers died in 2019 from past exposure to asbestos.

Companies Connected to Asbestos Mastics

Companies that manufactured construction mastics and gunning mix include:

  • Amchem, Inc. (Benjamin Foster Company)
  • Harbison-Walker Refractories Company
  • Insul-Mastic Corporation of America
  • North American Refractories Company
  • 3M (Minnesota Mining and Manufacturing Company)
  • Owens Corning Fiberglas Corporation
  • Johns Manville

Some brands of these products include:

  • Castable Mix 204
  • H-W Lightweight Castable #10
  • NARCO Aerogun
  • NARCO Lite Castable
  • NARCO Lite Gunning Mix
  • Owens Corning Type II Mastic
  • Steelplant Castable B

Diseases Asbestos Mastics Can Cause

The National Emission Standards for Hazardous Air Pollutants considers construction mastic a Category I non-friable asbestos-containing material. This classification indicates that mastic contains 1% or more asbestos and may emit asbestos fibers if disturbed.

When working with asbestos-containing mastic and gunning mix, fibers are released if the material is ground, drilled, cut or abraded. Renovation and demolition projects also damage these materials, which can lead to asbestos exposure.

Gunning mix was often made with vermiculite and aluminum. The vermiculite used in gunning mix may be contaminated with asbestos. Before the mix is made into a paste, it comes in powder form and is packaged in bags. Asbestos fibers in opened bags can easily become airborne when gunning mix is being measured and mixed.

Asbestos in mastics and gunning mix is known to cause the following diseases:

  • Mesothelioma
  • Lung cancer
  • Ovarian cancer
  • Laryngeal cancer
  • Asbestosis
  • Benign pleural conditions, including pleural plaques

If you are diagnosed with an asbestos-related disease you should find a doctor specializing in your diagnosis. Specialists work at some of the nation’s best cancer centers, where they can connect you with innovative treatments and clinical trials.

Compensation for Exposure to Asbestos in Mastics

Lawsuits filed against manufacturers of mastics and gunning mix revealed they hid the dangers of their asbestos products. For example, internal documents from Johns Manville became public through lawsuits and showed the company withheld medical evidence from workers with lung disease. To protect their interests, they decided not to tell the workers who had signs of developing asbestos-related diseases.

As a result of asbestos exposure from mastics and gunning mixes, many personal injury lawsuits and wrongful death lawsuits have been filed against manufacturers of these products.

  • In the 1990s, two engineers and a worker filed lawsuits against North American Refractories Company, the maker of NARCO Lite Gunning Mix. The plaintiffs were exposed to high levels of asbestos dust when products were mixed. Witnesses testified that several NARCO products, including the gunning mix, released a high level of asbestos dust. No workers were wearing respiratory protection. As a result of the asbestos exposure, the engineers developed mesothelioma and the worker developed asbestosis. The jury found North American Refractories Company liable and awarded $7 million to the plaintiffs.

Asbestos litigation forced NARCO into bankruptcy. When it emerged from bankruptcy in 2008, the North American Refractories Company Asbestos Personal Injury Settlement Trust was created to pay future asbestos claims. The trust was funded with $6.32 billion.

An experienced mesothelioma attorney can review your case and let you know if you qualify to file a lawsuit in addition to filing claims with asbestos trust funds. Other sources of compensation include VA claims, Social Security Disability, workers’ compensation and treatment and travel grants.

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Abatement and History of Asbestos Mastics in Construction

Some states allow homeowners to abate mastic and gunning mix that is whole and intact, but this is not advised unless the homeowner is fully prepared to take all legal and safety precautions, which vary by locality. Mastic and gunning mix that has been applied to insulation board or lagging should be removed by a certified asbestos abatement contractor.

While some states allow homeowners to abate intact mastics and gunning mix themselves, most states require homeowners to use professional, trained contractors when removing asbestos products. The U.S. Environmental Protection Agency also recommends that only licensed, trained professionals abate asbestos materials. Asbestos abatement professionals also prevent homeowners from paying hefty fines if they break federal or state asbestos abatement regulations.

Homeowners can use the following guidelines to ensure professionals are adhering to laws and regulations when removing asbestos-containing mastics and gunning mixes.

Hired asbestos abatement professionals should:

  • Remove all furniture or personal items from the room
  • Cover nearby objects with sheeting and seal off the space to avoid contamination
  • Wear proper safety equipment (HEPA respirator, coveralls, gloves, shoe protectors and eye protection)
  • Scrape off mastic that has been softened by heating or applying a solvent material
  • Avoid creating dust or scattering pieces of mastic (wetting the material reduces dust)
  • Wipe down surfaces and clean the area with a HEPA vacuum
  • Seal debris in polythene bags and dispose of the materials in an asbestos-approved waste location

Many different mastics were produced for use during World War II. Adding synthetic rubber and other fibers to these mixes made them stronger and more flexible. Asbestos was added to these adhesives to make them resistant to extreme temperatures and chemicals. Adhesives like mastic and gunning mix have been used for hundreds of years, but the use of modern construction mastics and gunning mix containing asbestos began in the early 1900s.

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