Sometimes a thing is stored too long.
Dry goods that expire in the pantry, or adhesives that dry out for example.
Yesterday I visited that found box of stationary and found that the many envelopes that I had been hoarding for years had all sealed themselves up over the damp time spent in the shed this winter. About 3 pounds of pristine and pretty envelopes rendered useless by neglect. Now they are recycling.
Live and learn.