Do you mean the kind of photos that can be pasted by tearing off the back layer?

Generally, when pasting stickers, it is really easy to become warped if you are not careful.

The reason is basically that the surface of the sticker is not cleaned, or the hand touches the sticker on it when pasting.

Or the surface of the paste is rough.

Countermeasures:

(1) Wipe the pasted surface clean before pasting.

Wrap a circle of scotch tape around your finger first, and then get the sticker, so that some sweat stains on your hands won't stay on the side of the sticker.

The above methods can only be guaranteed for a few years at most. With the aging of photos, air drying and other factors, the glue on photos will fail.

It will eventually fall.

PS: If you want to post it permanently, you can consider the following two points:

Waterproof treatment of photos (one-step molding).

Use foam double-sided adhesive or all-purpose adhesive.