I previously talked about how to separate mint stamps that are stuck together. Of the methods mentioned in that article, soaking and steaming are the two methods most used to remove used stamps from paper. Although, I don’t recommend steaming because of the damage it can do to the stamps. Here again, if the stamp is valuable it might be better to leave it on the paper. Especially any stamp printed in the 1800s.
Soaking in water works for gummed stamps, but will not work for self-adhesive stamps. Removing self-adhesive stamps from paper requires using something else besides water to soften up the adhesive. The best thing that I have found for this purpose is Rosonol lighter fluid. It can be purchased at most any drugs store in the U.S.. Of course, the fluid is highly flammable, so care must be taken when using it.
First, find a container to hold the fluid. I use a watermark tray for this purpose, but you could use a small jar or a plastic container. Next, cut the paper close to the edge of the stamps. Lay a few in the bottom of the container and then squirt the lighter fluid over the top of the stamps until they are soaked. The soaking time varies, but should not take more than 5 or 10 minutes. Now for the messy part. The adhesive will soften, but will not separate from the back of the stamp. Slide the stamp off the paper and proceed to remove the adhesive as follows:
Spread a sheet of newspaper on your work surface and get yourself a pocket or other non-serrated knife. Place the stamp adhesive side up and gently scrape the glue off the stamp. Work from the top edge to the bottom edge of the stamp. When all the adhesive is removed place the stamp face down on a clean sheet of newspaper to dry. When completely dry, the stamps can be flattened by placing them between the pages of a thick heavy book for a day or two.