MSDS sheets: An evaporation rate is the rate at which a material will vaporize (evaporate, change from liquid to vapor) compared to the rate of vaporization of a specific known material. This quantity is a ratio, therefore it is unitless. General usage: The mass of material that evaporates from a surface per unit time (examples: 3 grams per square meter per hour, 1 inch per acre per month).
