2K pot life

[badabec]

Hello, Nisocoat 2 , Lechler and other 2K paints.
Touch dry in 15 minutes, pot life 8 hours.
How comes?
Is it a chemical reaction that requires air as well as hardener?
Just for curiosity really.

 

[brightspark]

dunno it goes like a block of rubber after 24 hours it must have a certain amount of air once its mixed

 

[charlysays]

Hello, Nisocoat 2 , Lechler and other 2K paints.
Touch dry in 15 minutes, pot life 8 hours.
How comes?
Is it a chemical reaction that requires air as well as hardener?
Just for curiosity really.

Good question tbf.
The difference is basically in the solvent levels. No significant cross linking happens for 8 hours with those paints. So they can sit in a pot (retaining most of their solvents) and remain workable for 8 hrs.

So whilst they're touch dry in 15 mins when applied as a thin film which rapidly evaporates the solvents, it's just that, touch dry because the solvents have mostly evaporated, it hasn't even begun cross-linking yet.

If you spread some of the paint out without hardener it'll still be touch dry in 15 mins, it just never goes hard.

 

[badabec]

So whilst they're touch dry in 15 mins when applied as a thin film which rapidly evaporates the solvents, it's just that, touch dry because the solvents have mostly evaporated, it hasn't even begun cross-linking yet.

I asked HMG, charlysays is exactly right.