Asbestos Millboard

Asbestos millboard is a stiff, gray board made mostly of asbestos fiber with a binder, used for heat and fire protection in ovens, furnaces, kilns, boilers, stoves, laboratory benches and electrical equipment. It is softer and dustier than asbestos-cement board and could be cut, drilled and broken by hand.

Origin

Millboard was made from the late 1800s on, pressed from wet asbestos pulp on board machines in a process similar to papermaking. It was a common industrial and household heat-shield material through the mid-1900s, with use declining in the 1970s and 1980s.

Significance in Asbestos Context

Because millboard was high in asbestos and fairly soft, cutting, sawing, scoring or breaking it to fit released dust, and it shed fibers as it aged and crumbled near heat. Workers who built or repaired furnaces, ovens and kilns, glassworkers, foundry workers, welders, electricians, lab staff and teachers all handled it, as did homeowners who used it behind stoves or heaters. It also appears as a lining in some fire doors and in older appliances. In a claim, millboard exposure is often brief and repeated rather than constant, so a clear account of how often it was cut or handled, and where it came from, helps experts and lawyers. Identifying the maker can be difficult, since the board itself was often unmarked.

Example Sentence

In the school chemistry lab, she cut pieces of asbestos millboard to set under Bunsen burners and hot plates for years.

Related Terms

Asbestos-Cement, Transite, Fire Door, Friable, Asbestos-Containing Material (ACM), Product Identification, Consumer Product Exposure

Notes

• Describe what the board looked like, where it was used, and how you cut or handled it.
• If old millboard remains in a stove, kiln or appliance, do not break or sand it; have it tested.