Found a stat that blew my mind about paint curing times

I was reading through some old training manuals from the 90s I found in my shop's back office, and it said painters back then waited up to 72 hours for single-stage urethane to fully cure before buffing. Now I can shoot a basecoat-clearcoat job and wet sand it the same afternoon with modern hardeners. Makes me wonder how many of those old jobs got ruined by rushing the cure time. Does anyone here still work with materials that take more than a day to harden?

2 comments

2 Comments

camerona7927d ago

Ngl that old stat about 72 hour cure times is actually pretty accurate for single stage urethane from that era, but you gotta remember those old hardeners weren't as aggressive as what we got now. The part about wet sanding basecoat-clearcoat same afternoon though, that's not quite right either. Even with modern hardeners, most clearcoats still need at least 4-6 hours before you can safely wet sand without gumming up your paper or leaving haze. Some of those fast hardeners can get you there in 2-3 hours if you force dry at 140 degrees, but it's risky. I still use a few materials like high solids polyurethanes that need overnight before polishing, especially in cooler weather.

ruby_sanchez4526d ago

Funny you mention the high solids polyurethanes needing overnight in cooler weather - do you think that's more about the colder temps slowing down the reaction or just the chemistry of those specific clears being fussy? Cause I swear I've had some that still feel soft the next morning even when the shop's at 70.