Quote Originally Posted by 76GMC1500
Most paint manufacturers sell a flattening agent. Pick the one that is compatible with your application. I do believe it reduced the UV resistance of the clear, but in the engine compartment that wont be a problem.
Not all flatteners will work in clear. Some leave little white specks. PPG makes a flattener that is recommended for clear. It is DX-365. You can mix a semi gloss or full-flat. The formula for mixing is on the can or product sheet. I've used it in Urethane clear, and it looks great, but I recommend full-flat, for a more even finish.