Is contact cement flammable when dry?
It will burn but not flash like new cement. The most flammable perts of the cement evaporate quickly.
To my understanding, NO. Here is a definition copied from the second link provided in the Source box below, OK? Liquids with a flash point less than 60.5 or 37.8 °C (141 or 100 °F)—depending upon the standard being applied—are considered flammable, while liquids with a flash point above those temperatures are considered combustible.[1] By this definition, a gob of dried contact cement is probably combustible, but certainly, not flammable. I've heard of low grade diesel, not needing a Flammable placard in shipment. Wood, for a quick example, is combustible. I think you could easily test this to your satisfaction with little butane torch. If your gob of dried glue, don't quickly ignite, it's only combustible.
Contact cement is a mixture of the actual bonding agent (the cement) and a solvent. The cement itself has a flammability rating similar to wood. It will burn as will wood but it is not a fire hazard like a low molecular weight solvent. The solvent is mixed w the cement to enable the installer to spread a thin film of the cement on the items to be cemented together. The solvent evaporates leaving the sticky cement which provides the adhesion. The solvent is flammable, in about the same range as is paint thinner or gasoline. However, once it has been evaporated and the vapors diluted the fire issue is gone. It is much like painting with a solvent borne paint; the solvent (often called paint thinner) is flammable. Once the solvent has evaporated away and diluted, the flammable issue is gone. You probably note that the directions tell you to have adequate ventilation. This is designed to dilute the solvent fumes and get them outside where they dilute further and decompose. This is critical.
