What caused my Old photo album cover to be sticky?

A sticky photo album cover can be caused by several factors, including the breakdown of adhesives used in the album, exposure to heat or humidity, or the presence of moisture that attracts dust and grime. Over time, the materials in the cover can degrade, leading to a tacky surface. Additionally, if the album was stored improperly, such as in a damp or warm environment, it may have accelerated this deterioration.