This all-purpose sealant can be used to fix cracks, seal windows, and fill joint gaps. Good caulking compounds are weatherproof, heatproof, waterproof and durable. Caulk has the same texture of toothpaste and is applied with a caulking gun or masonry knife to ensure a strong bond. Before 1970, manufacturers of caulk would use asbestos because it acted as a fire retardant. Ovens, fireplaces, boilers, pipe joints, ducts, brickwork, and exteriors are common places where caulk containing asbestos may be found. In its liquid form, this material is not dangerous. However, once it dries, the caulk becomes vulnerable to cracking and chipping.
Some caulks actually contain almost 100% asbestos, but most were made up of about 25% of the dangerous mineral. In fact, chrysotile was the only asbestos allow in caulking compound after 1970. Chrysotile has curly fibers to increase malleability and many other types of asbestos have sharp, needle-like fibers. This meant that chrysotile was less friable, or able to be broken down by hand, and therefore less likely to release its fibers into the air. However, there is no type of asbestos that is completely safe.
The asbestos fibers can’t be released unless the caulking gets damaged. This can happen with age, water, impact, sanding, scraping, or an attempt to remove the caulk. If you think that the caulk in your house may contain asbestos, leave it alone, especially if it is in good condition. If it is not, talk to a professional for removal. Scraping or chipping the caulk sends tiny particles of the substance into the air, and without proper protection, these dangerous particles can easily be inhaled into the lungs, which can cause severe respiratory problems.