Water-activated adhesive

Water-activated adhesive: Stamp gum designed to adhere to envelope paper only if the gum is moistened. All gummed stamps before 1963 used water-activated adhesive.

Water-activated adhesive: Stamp gum which adheres only when it is moistened.
Watermark: A intentional thinning of paper during its manufacture to produce a translucent pattern.

Water-activated Adhesive - Stamp gum that adheres when it is moistened.
Watermark - A deliberate thinning of paper during its manufacture to produce a semitranslucent pattern.

(34¢) Flag over Farm (water-activated adhesive pane of 20)
12/15/00
3449 ...

Christmas stamp, although the experiment was judged a failure and not repeated for many years. Traditional gums remain in use, although differentiated by calling them water-activated. All Israeli postage stamps feature a water-activated adhesive that ...

See also: Adhesive, Stamp, Self-adhesive, Pane, Strip