Dear Donia,
How do I safely pull apart a folded old birth certificate with stuck together pages?
Q. Dear Donia,
A. Dear Debbie,
I hate to be the bearer of bad news, but it is unlikely that you will be able to pull the birth certificate apart. There are different reasons for paper to stick together like you describe. One is that the paper got moldy and is essentially fused together. If the cause is mold, it is unlikely that you will be able to salvage the paper if you try to peel it apart. Another reason is that the birth certificate got wet at some point and the sizing in the paper (frequently gelatin) solubilized, moved to the surface, and then dried. When gelatin solubilized, it essentially becomes a glue and thus the paper is glued together. My suspicion is this is the case here. Unfortunately, you can't reverse this sort of sticking by simply pulling it apart.
If your reason for opening the birth certificate is pure curiosity and not that this is an important family heirloom, you can humidify the document which should help soften the sizing to allow you to gently prise open the document. I have attached some directions for humidifying and flattening your certificate if you want to attempt it. If this is an important document for your family, it would be best to consult a conservator. You will be able to find several in your area by searching the American Institute for Conservation website.
Good luck!