Wipe clean with a squeegee (Picture Window)
Starting at the top left, pull the squeegee over the soapy pane in a reverse-S pattern (left-handers would start at the top right). At the end of each stroke, wipe the squeegee’s blade clean with a lint-free rag. Cloth diapers or old linen napkins are perfect for this task.
Dry off remaining drips (Picture Window)
Remove any water remaining on the edges of the glass with a damp, wrung-dry chamois, which soaks up wetness without leaving streaks. Dry the windowsill with a rag.
Customize the squeegee (Multipane)
To clean a divided-light window, you need a squeegee that fits the panes. Weingard uses a hacksaw to cut one to size. He trims the metal channel ¼ inch narrower than the window pane, then files the cut edges smooth. With a utility knife, he cuts the rubber blade to the pane’s full width and fits it into the channel so that it projects 1/8 inch at each end.
Scrub the panes (Multipane)
A handheld sponge or hog-bristle brush works best on multipane windows. Weingard prefers natural sponges. “They’re firmer and more absorbent than synthetics,” he says. Using the same solution of a
squirt of liquid soap in water, he rubs each pane from left to right, top to bottom, working the sponge edges or brush bristles into the corners to loosen dirt.
Wipe clean with a squeegee (Multipane)
Pull the squeegee down each pane in a single stroke from top to bottom. After each stroke, clean the blade with a rag so it doesn’t leave streaks. (If the squeegee squeaks a lot, add a bit more soap to the water.) As above, remove any streaks on the glass with a chamois, and dry the muntins and sill with a rag.
Get rid of stubborn spots
Over time, hard-water runoff from masonry or rain falling through metal window screens leaves stubborn mineral stains on glass that normal washing can’t erase. So after a regular cleaning, Weingard wets the glass and gently “supercleans” it either with fine 000 steel wool (if the panes are small) or with Barkeeper’s Friend, which contains oxalic acid. (Other brands of powder may scratch the glass or fail to remove stains.) He mixes the powder into a paste on a wet towel, rubs away the stains, then rinses and squeegees the glass twice to remove the residue. Even with that treatment, the staining generally comes back in about six months.
To get rid of stains for good, Weingard recommends the application of 3 Star Barrier Glass Surface Protectant, a clear polymer coating. “After the stains are gone, you just put the coating on with a strip applicator and squeegee it off,” he says. Protection against staining is permanent, as long as the polymer is reapplied after each regular cleaning.
Originally posted at: https://www.thisoldhouse.com/how-to/how-to-clean-windows-pro