So, you’ve saved a few hundred envelopes with stamps or purchased a stamp mixture. Now how do you get them off that paper? It may sound odd to first timers but you simply let them soak in cool to room temperature water for 5-10 minutes. But first, be certain that the envelope itself isn’t a First Day Cover or have some other historical or personal significance. If it does, it’s better to archive the whole envelope. While so much is made of safe handling, it seems plain wrong to dump your stamps in water. While very few stamps have ink that runs after being doused, current US stamps do not.
Once you’re sure you wish to remove the stamps from their paper select a container large enough to give your stamps plenty of room to soak. Selecting too small a container or using too little water will make the gum (or glue) concentration in the water damage your stamps. So, use plenty of cool to room temperature water. Once the stamps have soaked for 5 to 10 minutes, carefully remove them, one by one, from the water and peel the paper from the stamp. Then place the stamp face down on a blotter or newspaper. When using newspaper, use only news print with low-rub ink. If your hands are black after reading the paper, it’s not low rub.
Once all your stamps have shed their paper and face down on the blotter, give them time to dry. When they have dried, they’re ready to be placed in an album, stock card, or other enclosure.
— James the Web guy