Most stamps collected have been used as postage. Unlike uncirculated coins, that’s part of what makes them valuable, since they then acquire a history and often interesting cancellation or other marks.
But once they form part of a collection they are most often separated from the envelope or package they were adhered to. The most common method used by amateurs for doing that is soaking. But soaking is equal parts art and technology – done improperly it’s easy to ruin an otherwise valuable stamp.
Adopt the Hippocratic Oath taken by physicians since the days of Ancient Greece: First, above all, do no harm.
Separate out the stamps you intend to collect, then try to find ones with similar ink and material for practice. Until you get the technique down, you’ll want to tread with extreme caution. After you’ve had ample practice, you’ll want to… tread with extreme caution.
Get a medium-sized clear glass bowl. This allows you to see both top and bottom of the stamp. Fill the bowl about half full with warm water. The water should be warm enough to soften the adhesive. Take care, though. Excessively hot water will raise the probability of ink running over the surface of the stamp. It also softens the stamp to the point that tears are almost inevitable.
Trim the stamps of any ‘covers’ (envelops or packaging material, which are sometimes left on to form a larger collectible, if they have unique and valuable features). Leave about 1/4 inch around the stamp so you have an edge to work with as you separate off the stamp.
Using a pair of stamp collector’s tongs is very helpful for some of the following steps. These are different from ordinary tweezers, but those will do in a pinch if they have flat, not serrated, surfaces.
Lift the stamp by the edge of the remaining cover and place it gently on the surface of the water. It may float. If so, that’s helpful since it will help wet the back while leaving the front drier. The goal is to soften the glue enough to separate the stamp from the envelope, while maintaining the stamp in good condition.
If the stamp sinks, don’t worry overmuch. Provided the ink doesn’t run and the stamp doesn’t tear, there won’t be any permanent harm.
Allow the stamp to soak for 5-15 minutes. You’ll need to experiment, since the time can vary depending on the water temperature, the glue used, the age of the stamps, etc.
Also, water varies in mineral content, which will affect the process. It’s best to use distilled water whenever possible. Special soaking solutions exist, but plain water is safe and effective provided the guidelines are followed.
After soaking, pull the stamp gently up and slide it onto the side of the bowl. Work loose the stamp from any part of the envelope still adhering. If the stamp is wet, the usual condition, this is the critical step. Tears are most likely at this stage. Proceed gently.
Place the stamp face down onto a soft, dry cloth and allow to air dry for at least 20 minutes at normal room temperature, then examine and store.