I have had a number of postcards expire recently. I realize that there can be many reasons why this happens, but I was noodling about it the other day and started looking at my glue stick.
I have used glue sticks successfully for years to apply labels for shipping, and have been using them to apply printed postcrossing addresses, especially those that are more complicated.
But somehow, without noticing, I had recently gotten my hands on a glue stick apparently designed for schoolchildren, and when I looked at the cutesy label (think ABC/123) I saw the words “water soluble”. Uh Oh. I live in a rainy climate, and while mail doesn’t necessarily get drenched as it travels the world, I’m sure there is plenty of humidity along with rough handling. I wonder how many of my address labels simply peeled off.
I immediately went out and purchased a professional grade Scotch 3M glue stick marked “permanent” on the label. I’ll have to see if that makes an improvement.
Hopefully your cards will still arrive. I think we’ve all had more cards expiring in the past few months than normal due to a variety of disruptions in international shipping and international mail service. But I applaud you for thinking outside the box for additional culprits.
Years ago, when I was sending wedding invitations out (not postcards), I also glued the typed addresses onto a navy-blue envelope so that it is more visible. Like you @racer7949 , I used elementary grade glue thinking it would be alright. Most of the labels ended up peeling right off in transit and they were eventually “returned to sender” … fortunately. It was lucky also that I sent out a small batch at first (about 10-12 invites?), so after the majority of that small batch was returned, I upped my glue game with UHU.
Nowadays, if I do print out a label (I notice that they are received faster in China if I use their language in the address), I use either label sticker paper, or I print on plain paper and use clear shipping tape to stick it onto the postcard.