Typically you will see black mold marks on windows that have some sealing problem. Most of the time caulking and repainting the outside of the window will repair this problem. Start by cleaning up the window using a sander. If you find an area that is totally rotted away you may need to replace the entire window however many times using something like Exact Match wood epoxy or even Bondo body filler can be used to fill the rotted areas. It is best to use a hardener on the soft but not rotted wood prior to putting in the epoxy. Once filled it is best to shape and sand before the epoxy hardens all of the way. Shape it as best as you can and sand it flat. This is a really simple to do wood repair.

USE AN EXTERIOR OIL PRIMER!!!! Many stores sell exterior latex based primer. It is a waste of time using this stuff because the paint will peel off in a matter of a year or two in most cases. A good oil primer is not cheep but you don’t want the rest of the windows to rot. Prime and allow it to cure for 24 hours.

Paint with a high quality exterior paint. I prefer using a semi gloss because it stays clean longer.

Now to address the inside of the window. Take a little sand paper and clean up the area with the black mold on it. Use some mold killer and allow it to fully dry. Some black will remain so it’s time to correct the problem using the Exact Match Wood Touch Up system. Fan out the color cards and find the color that closely matches the surrounding wood.  Put a few drops of activator on the card and apply the stain to the damage. The black will be gone and you have permanently repaired the window. If you want you can topcoat the repair with some urethane for an even more durable repair.

This repair can save you thousands of dollars!