colorful house with red front door
Photo: Nikreates/Alamy
Q: The door or the painter could be to blame for a splotchy finish

A: Q: Last year I purchased a wonderful fiberglass door, but my husband painted it with old paint and the result is blotchy and looks terrible. How can we remove the paint and then repaint the door so it looks the way it should?

—Ruth Ficker, Jerseyville, IlL.

John Dee replies: It might be the paint, or it might be the painter's technique. Here's the test: Sand a section with 120-grit sandpaper. If the paint powders, there's nothing wrong with it. The blotchiness is probably from lap marks where one area of the door has more paint on it than another. The remedy is to sand the rest of the door lightly and repaint it. But this time, paint each individual panel first, taking care to wipe the excess off the rails and stiles. Then paint each rail, followed by each stile. This method will enable you to keep a wet edge and avoid lap marks.

If the paint rolls up when you sand it or seems gummy, then the paint is at fault and you'll have to remove it entirely with a chemical stripper. Because stripper will eat into the surface of the fiberglass if it sits for too long, you want to leave it on just long enough to loosen the paint, then immediately scrape it off with a putty knife. Repeat if necessary. On doors with a textured finish, a small nylon brush or a Scotch-Brite pad will get at the paint in the tiny recesses. Neutralize any remaining stripper residue by rubbing the door with a Scotch-Brite pad dipped in denatured alcohol, then wipe with a rag (and more alcohol if necessary) until the rag comes away clean. Allow at least two hours for the door to dry, sand it lightly, and paint it, this time with fresh paint.

(John Dee, a painting contractor in Concord, Mass., has demonstrated his fine finishing techniques on several episodes of This Old House.)
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