If humidity is too high (80% +), it will adversely affect the curing and adhesion process. A couple of things can be done to minimize these effects. One is to provide air circulation or an air flow that vents the air away from the coated surface. This may assist in reducing the humidity but may also circulate particles and debris that may become embedded in the wet paint. Secondly, apply Rust Bullet with a brush. A brush application tends to trap less air and moisture and is therefore the best application method in a high humidity zone. Apply additional, thinner coats rather than fewer, thicker coats. This will help eliminate the formation of bubbles or blisters on the coating surface which can occur if the solvents cannot be expelled. The formation of humidity bubbles or blisters can result in poor adhesion, which in turn, may need re-sanding and a touch up.