I can across a can of Alumahyde II that I bought at least 8, probably 10 years ago. It was still in the sealed plastic bag so I am sure I never used it.
I planned to paint a magazine to see if the paint was still good. Prepped everything per directions, but dang, nozzle is clogged! Must have slow-leaked at some point through the years.
No worry, I have spare nozzles and cleanout nozzles. Ran a cleanout nozzle and then threw a fresh fan pattern nozzle on and sprayed on the paint.
Let it air-dry a bit, and then baked in the grill on lowest heat for a full day, and then let it sit in the hot garden shed for about a week.
Paint is perfect. Hard as a rock, looks great, no complaints at all.
So if you are wondering about the shelf life of Alumahyde, I can vouch for it.