A customer asked me the other day about how to identify stamps when they are attached to a cover. In some cases, a grill or a watermark is the determining factor. However, it’s not always possible to make that determination when the stamp is on a cover. Sometimes a grill can be measured from the front of the stamp. Or watermarking the stamp is possible. But what do you do when you still can’t tell?

Sometimes the stamp needs to be removed from the cover. Then it can easily be inspected, watermarked, and so forth for precise identification.

Before I explain this process, I want to be clear. Removing stamps from a cover for identification purposes and returning them to the cover so that they are intact is not an easy process. I recommend trying this on some inexpensive covers first to get experience doing it. Done incorrectly, you risk destroying the stamp and possibly the cover. Expertizing committees have techniques for examining and identifying stamps on cover that are not accessible by the ordinary collector. For valuable items on cover, I highly recommend sending them to one of the recognized expertizing committees. The few dollars that the certificate costs is worth it compared to the potential of losing lots of money if you do the process wrong.

To remove a stamp from a cover and return it to it’s original spot, you need to sweat the stamp from the cover. Notice, I said sweat, not soak!

This requires a sweat box. In simplistic terms, this is a box that creates high humidity within an enclosed compartment. After exposure to the sweat box, the stamp can be carefully lifted from the cover, retaining some of it’s gum. The stamp can be carefully dried and examined. And with light moisture, it is carefully applied back to the original cover in its original position.

I’m purposely leaving out a lot of details. Removing a stamp from a cover and returning back to it’s original condition is part art and part science. It’s not a technique that can be mastered in a few short descriptions. It takes patience and practice. In many cases, it’s best left to the experts.