Im trying to get my chasis all finished and i keep having days of 70% humidity and my gut says thats a bit too high for good adhesion. Im using some rattle can self etching primer and krylon rust tough and the cans just say to not spray them in high humidity, but it doesnt give a number.

Is there any paint Guru that can give me a hard number for what is too high of humidity to paint?

thanks for the help

Seventy percent seems a bit high for me. I couldn't give you an actual number, I've just stayed away from painting when it felt at all humid to me.

The pros go to a lot of trouble to get low humidity with their booths.

yeah, the other problem i have is that i live in the south and its only gonna get worse

I didn't know it got less than that, lol :laughing:

I sprayed some flat paint yesterday afternoon. It still wans't dry today 12 hours later.

One thing you can do to help the situation is use a turbine HVLP system. They heat the air to drive out the moisture.

I'm using Por-15 and their Chassis coat(black). The paint store people said that the Por-15 actually gives a better result when "humid". They didn't say anything about the Chassis coat though, which can be applied directly over the Por-15 without a primer coat. Another option for you may be to rent/borrow some de-humidifiers for yor painting area, if it is your garage/shop.

POR-15 is a different animal. Even there, too high humidity will cause it to dry too quickly and you'll run into problems. Urethanes are moisture cured and spraying them in high humidity can cause them to dry between the gun and the object being sprayed.

ive been spraying rattle cans in about 20% in my basement. did my old b2 with a spray gun during the winter in a heated garage so humidity was down there aswell. not much help but figured id chime in