Most products used for paint finishing discourage them being used in the sun. Why? Is it that sun has a magic that will change the molecules in the product or is it because the surface temperature might be too hot. I’m in a situation where my work involves a vehicle that can’t be moved, but doesn’t get warm from the sun, less than 100 degrees, until about 9AM this time of the year which allows a couple hours work time before switching sides. This OK? TIA