I coated two valve covers and they came out nice with a ceramic look to them. However there was a little spot I missed. I put a second coat on them but when I say a second coat I mean I just misted them but hit the spot I missed good. When they came out of the oven they had a dull look to them. Does anyone know if it was because I was cheap with the powder and should have hit the whole thing heavier or is there another possibility? They were dull and patchy looking. Would it be alright to give them a third heavy coat?