Why Do Hinges Not Stick To Some Stamps?

I use Lighthouse hinges and they worked fine, but I have aquired a lot of 40-50 stamps and many can't be hinged. Simply drops off.
Whats wrong?

Probably bad or maybe old hinges?

Peter

I have had this problem also and some specific stamps don't take a hinge at all. I can't name an example off the top of my head though, but in my case it would mostly international early 20th century.

I use following workaround: take a full hinge (unfolded) and put it across whole back of stamp. Let it dry and then attach another regular (folded) hinge to hinge. I can't explain why this would work except surface attaching to stamp is much larger.

Could the hinge have been folded the wrong way? I don't believe both sides have a water activated adhesive. I occasionally have had this happen, folded the hinge the other way and it stuck right away.

Regarding the previous post, if the hinge doesn't stick to the stamp why does the unfolded full hinge stick?

I'm curious about that packet of 40-50 stamps. Do they have some kind of common thread? For example, country, era, issue, etc?