Blech
My father was a philatelist, a stamp collector. In addition to his collection, I've inherited countless numbers of stamps that we can use for regular postage. I've used up all his stamps that are self-adhesive. Now I'm into the stamps you have to lick.
Bleccchhhh!
I'm surprised anything got mailed before self-adhesive stamps. Licking them is disgusting. A barbarous, barbarous activity.
K-
I'd hate to be wasteful but I wouldn't use those stamps. Maybe if they were garlic-flavored......
Try just using a damp sponge. There used to be little water wheels also. I don't think the office supply stores carry these anymore though since everything is self adhesive now or electronic. Since going online with payments, I only need stamps for rebates, cards and Christmas.