The goal is to have perfectly flat clear coat, with no texture, no ripples, no imperfections. To get there, the clear coat must be sanded with hard blocks and aggressive enough sand paper, 600 grit. If perfection is the goal, this is true, no matter how many coats of clear are sprayed.
The question then becomes, how much clear is needed to be able to sand it flat. The answer depends slightly on what clear coat it is, but generally, 4-6 coats will be needed.
The next common question? Is all the clear sprayed at once, or is it sanded and cleared again, a ‘flow coat’. The answer is all at once, and here’s why. When wet sanding clear coat, it cannot be sanded past the layers that were just sprayed, even if it’s more clear coat underneath. If you break through into the first round of clear coat, you will see a dull edge from the previously sanded clear coat. It will look like a bad blend edge.
All this means that no matter what, 4-6 coats of clear are needed, sprayed at one time, in order to have enough material to sand it flat enough. So adding a second round of clear coat only adds extra solvent, extra material, extra time, and a little extra die back from all the additional solvent.
The important part is knowing the clear coat you’re using, and being very particular with it’s flash times, and not piling heavy coats on.
I have always liked using high solids clears. I have usually used Spies Hecker products. I have always been under the impression that if you are spraying high solids clears, going over 3 coats was kind of a bad thing. I honestly never understood why it would be a bad thing if the dry times between coats were utilized correctly. What is your input on that? I was also wondering would using a medium solids clear be better for that amount of coats? Thank you!
Are you using a mil gauge to check how much clear you put on and how much you sand off ? Example if you have three mils of dry clear on a panel and and sand off 0.5 mils you have 2.5 mils left on the panel. You can’t manage what you don’t measure.
I used to believe, like many, spray 5, sand off 2. Coming to an accurate knowledge of the product, you become aware of such things as solvent pop. Good high solids clear, I can’t stress it enough: pay attention to flash times!! Patience..