How to Clean Windows Without Streaks

Streaks nearly always come from one of four things: too much cleaner, a towel that sheds lint or pushes dirt around, dirty water, or glass that dries before you’ve finished with it. That last one is the Colorado problem. Humidity on the Front Range stays low most of the year, and a pane in full sun at altitude warms up quickly, so cleaner can dry into a film in the few seconds between spraying and wiping.

Fixing it is mostly technique. You don’t need a special product.

Why spray and paper towels streak

When you spray a window and wipe it with paper towels, you spread a thin layer of cleaner and loosened dirt across the glass and leave it to dry, and it doesn’t dry evenly. Paper towels shed lint, and many spray cleaners leave a residue of their own. The window looks fine straight on, then the afternoon sun hits it at an angle and every swirl shows.

Window cleaners take the water off the glass instead of waiting for it to dry, and a squeegee is how they do it.

What you need

• A bucket of warm water with a few drops of plain dish soap. Too much soap is the biggest single cause of streaks, so keep it to a few drops.
• A scrubber (also called a strip washer) or a clean sponge.
• A squeegee with a sharp, undamaged rubber blade. A 12 or 14 inch one covers most house windows.
• Two or three lint-free cloths. Microfiber works, and so does a chamois, which is what we use.
• An old towel for the sill.

Step by step

1. Pick the shade. Do the sunny side of the house in the morning or evening, or wait for cloud. This matters more here than in most places.
2. Brush or wipe the dust off the frame and sill first, so you aren’t washing grit onto the glass.
3. Wet the whole pane with the scrubber, enough that it stays wet while you work. If patches start drying, wet them again.
4. Wipe a dry strip about an inch wide along the top edge with your cloth. It gives the squeegee a clean place to start.
5. Pull the squeegee across or down the glass in one smooth stroke, overlapping the last stroke by an inch or two. Hold the blade at a steady angle with light, even pressure.
6. Wipe the rubber with a cloth after every stroke. Water left on the blade gets dragged into the next pass.
7. Run a dry corner of the cloth along the sides and bottom, where the squeegee leaves a thin line of water, then dry the sill.

Stick to glass you can reach from the ground or a short, stable step ladder. A squeegee isn’t worth a fall. For the outside of the house, including tilt-in sashes and poles for the upstairs panes, see how to clean outside windows.

Reading the streaks that are left

What the streak looks like tells you what went wrong.

• A haze across the whole pane means too much soap, or old residue from spray cleaners. Wash it again with less soap.
• Lines at the edge of each stroke point to a worn or nicked blade, or strokes that don’t overlap. Replacement rubber is cheap.
• A drip line along the bottom means the edges weren’t dried. Go back over them with a dry cloth.
• Swirls come from a cloth that was damp or dirty. Switch to a fresh one.
• Cloudy spots that won’t wipe away aren’t streaks. They’re usually mineral deposits, and hard water spots need a different approach.
• If you can’t get rid of a streak no matter how many times you wipe, it may be on the other side of the glass. A quick wipe on each side will tell you which.

Inside glass

Interior panes are easier. There’s less dirt and no sun beating on them, and for most of them a lightly damp microfiber followed by a dry one is enough, without the bucket. Handprints and dog nose smudges on low panes come off with the same soapy water. Lay a towel over wood sills and floors first, since a squeegee sends the water somewhere.

When to hand it off

Tall panes, second-story glass and great-room walls that need a long ladder are where doing it yourself turns into a safety question. That glass is a lot of what we do. Every pane is cleaned by hand with a squeegee and chamois, inside and out, with the sills and screens included. Send the quote form for a straight price, and see what moves that price if you’re comparing.