The history of adhesives dates back to ancient Egypt. Man's first application of a water remoistenable adhesive to paper made use of naturally occuring water-activated gums. It was in the 1830's that the British Postal Service first put an adhesive on the back of a postage stamp. It was not until 1841 that an envelope appeared which could be sealed without the use of sealing wax. By 1850, envelope-folding machines were in operation.
Remoistenable adhesives are dried adhesive coatings on a substrate. These coatings upon moistening with water develop adhesiveness.
Source: Thesting of Adhesives, TAAPI Monograph Series no. 26