From ‘The Times’- 8th November 1843
Persons who found a difficulty in attaching the adhesive stamps firmly to their letters, are recommended to wet the letter, in preference to applying the moisture directly to the gum; as the latter plan involves some danger of washing the gum off the stamp. Further, it is advisable to wet the face of the stamp slightly, in order to prevent the stamp from curling up at its edges, which, without this precaution, it has a tendency to do; for when the gum imbibes the moisture it immediately expands, and thereby renders the gummed side of the stamp somewhat the longest, but by wetting the printed side also the two sides are equalized. Or the stamp may be dipped wholly into water instead of wetting the letter, provided the surlus water be shaken off immediately. When the stamp is put on it should be pressed gently with a piece of clean blotting paper.