A flammability rating of 1 means that glycerin must be preheated before it can ignite. It must be thoroughly heated and must be very hot to catch on fire. Although it does have such a low flammability rating, it is still a combustible liquid and can become ignited under the right conditions.
Despite the fact that is both combustible and flammable, glycerin is not known to be harmful to humans. It is water soluble and is not difficult to eliminate if it were to get on clothing or skin. Although it is not harmful in its own state, glycerin can cause irritation to skin and eyes and can be fatal if ingested when mixed with other chemicals.
Glycerin belongs to the reactivity groups of alcohols and polyols. It is a clear, amber or brown colored liquid that remains stable even under ignition conditions. Although it is not often known to react to other substances, other liquids similar to it with the same classification have been known to react with cellulose-based absorbents. Glycerin has many different names, including glycl alcohol, glycerol, propanetriol and osmoglyn, which are all made up of the same components as glycerin.Learn more about Atoms & Molecules