How to Paint Double-Hung Windows
If someone’s painted the upper sash of a double-hung window shut or the pulley/counterweight system needs repair, consider correcting the problem before you start painting. Inevitably, these repairs will damage the finish, so now is the best time to take care of the situation. When you’re ready to paint, follow these steps:
Reverse the positions of the lower, inner sash and the upper sash.
Leave both sashes slightly open.
Using an angled 1-1/2 inch sash brush, paint the lower exposed portion of the outer sash.
Use a brush with very little paint on it to coat the vertical, outside edges of the sash. The dry-brush technique prevents paint from running into the crack between the sash and the stops, where it may cause the window to stick.
After the paint dries, return the upper and lower sashes to their normal positions, but don’t close them completely.
Move the sash as soon as possible to break any paint bond in these cracks before it dries completely. If, despite your best efforts, the sash sticks, use a serrated tool known as a paint zipper or the tip of a utility knife to cut through the paint that binds the stop to the sash.
Paint the remaining portion of the outer sash and the entire inner sash.
Don’t paint the outside sloped portion of the window (the sill). This area is an exterior surface, and you must paint it with an exterior paint, typically while painting window exteriors.
Switch to a wider 2-1⁄2-inch angled sash brush to paint the casing.
As you’re painting around the glass, lay the paint on in the middle of the area you’re painting rather than starting in a corner. Then, with less paint on the brush, work from the corners out, dipping your brush into the paint you initially laid down as necessary.
Cut in the casing where it meets the wall. Then do the stops and paint the stool.
The stops form the inner edge of the channel for the inner sash.
After the sash has dried, paint the channels.
Slide the sash all the way up to paint the bottom half of the channels and, when the paint dries, slide the sash all the way down to paint the upper half. If unpainted metal weather-stripping lines the channels, don’t paint the stripping.