Well, these particular ones I didn't do, but I use Pure Citrus Orange Air freshener. I know it sounds weird, but it works. I spray a little bit on the back (envelope side), wait a few seconds, then pull off the paper. Then I put on a little more, and scrape off the glue with a credit card. (Lay the stamp face down on a smooth surface, like plexiglass). It's messy, but it works. more information can be found at: https://sites.google.com/site/myrtlebeachstampclub/stamp-tips
Thanks for the info. Sounds like quite a procedure. Somebody told me Bestine works well too--it's a contact cement remover. But I can't find any. I'll have to look for the Pure Citrus.