lo all.

painted up a replacement wing for my customer a few weeks ago (2 infact) and used sikkens lv superior hs clear. had it on the infrared during all the paint to keep it at a temp around 20c, was high builded, then blocked , left over night then base coated (solvent ppg) nd then got 2 coats of the sikkens. after a flash off it got a good day infront of the infrared at about 40c

i have use this exact batch before and never had this following issue, i fitted the wing the other day and wet flatted it all down with p2000 to de-nib. sanded great and it felt nice and hard. came to buff it (used farecla g3 ultra and a new foam) and in certain places whilst polishing the clear has dragged like it had not gone hard

the paint was definitely mixed to the tds like always, but it seems to have not gone off properly. it feels hard to the touch but will mark with a fingernail if you push down.

can clear or hardener go bad over time?

Yes stuff does have a shelf life how old is it?

But I bet problem was temp related, A heat lamp is concentrated heat in one area.
if that was your only source of heat while curing and moving it around while it was curing I could see some areas not having enough heat to fully cure.

If an area dropped below 65f while curing its gonna slow way down if not stop.

no i have a proper spray booth with a large infrared in it, the entire panel was at a decent temp for the entire thing.

the exact same paint (read batch here) i did a red car in i got back in today (customer damaged the door edges on a wall) and his paint is hard as rock.

at most it was a month, maybe 2 between that car and doing the wing.

I wouldn't think a month or two old is enough time to cause any problems unless they hadn't been sealed properly? or they had gotten really cold like below freezing.

It may be possible that it went bad from trapped air in the can?
I have heard of others resealing there cans with inert gas that's heavier than air when they partially use a can just to protect it from going bad when they know its gonna be a while before they use the rest just to prevent air from getting to the contents.
I like to error on side of caution and just go buy fresh activator, throw the old stuff out.

Your sure you mixed it right?