We painted our porch. Noted some dull areas a few days later. We applied a second coat of black paint. It rained that night and now that area has turned milky white. How do I fix this?
Moisture was trapped in the paint, causing "hazing." This may fix itself, if given the opportunity to dry out. If, within a week of dry weather, the milky-ness hasn't gone away, simply repaint. If you used an oil based paint, be sure to lightly sand & wipe away the dust with a rag dampened with mineral spirits. If a water based paint, clean the area to remove any dust or dirt.