How to Acquire Stamps : Page 152
Certain other stamps are printed in fugitive colors andwill "run" if soaked in water. Some early U. S. postagedue stamps are so affected. If you note the water in whichyou have placed your stamps begins to take color examinethe lot and discover just which stamps are leaching color.Remove them.
Stamps of High Value
By and large the soaking process described in the fore-going will not hurt even the most valuable stamp. Justmake sure it is not printed in fugitive ink or on chalkysurface paper.
If you have doubts or are timid about "taking a chance"there are various gadgets for removing individual stampsfrom paper. They are available from most all dealers andcome in a variety of trade names.