(RCSD) Looking Back #214 - Gum

Gum

Referred to in the early history of philately as
'cement', gum is the mucilage applied to the
backs of adhesive postage stamps, and has
as its basis crystalline gum arabic.

The raw materials vary in colour from the
finest 'water-white' to a deep orange, and
these variations in colour are sometimes
the only clue to the different printings of an
issue which has been frequently reprinted.

A perfect mint stamp is one with all its
original gum (o.g.) as issued by the post
office; an old stamp with full gum is referred
to as 'o.g.' -- original gum -- one to which no
addition of fresh mucilage has been made.

In hot weather or under a strong light
contraction of the gum can often cause mint
stamps to curl. In extreme cases
considerable damage can be done in this way.

A temporary cure can be effected by
breathing gently on the back of the stamp.
Many modern stamp adhesives are dextrines,
or of similar character, while some U.S.A.
issues had an extract of cassava root
(tapioca) as an adhesive.

[See : Do You Like Tapioca? Past Notes #145]


- R. J. Sutton 6th edition revised by K. W. Anthony
The Stamp Collector's Encyclopaedia
Published 1966