· Michael Blair
Streaks are dried cleaning solution and redistributed dirt. They come from working too hot, using too much product, and drying with the wrong material.
Do not clean in direct sun
Solution drying on the glass before it can be removed is the single largest cause of streaking, and a Nashville afternoon on a south-facing window dries it almost immediately.
Work on the shaded side of the house, or early and late in the day.
Less product, better tools
A small amount of detergent in water is enough. Excess product leaves residue that streaks as it dries and attracts dirt afterwards.
A squeegee with a good rubber blade beats any cloth, and the blade needs to be clean and undamaged — a nick leaves a line every pass.
- Never in direct sun
- A few drops of detergent in water is plenty
- Squeegee with a clean, undamaged rubber blade
- Wipe the blade after every stroke
- Microfibre for detailing, never paper towel
Technique
Overlapping strokes with the blade wiped between each. Work top to bottom so runs go onto uncleaned glass rather than finished glass.
Detail the edges with a dry microfibre cloth, which is where the last of the water sits.
When it is not the cleaning
Hard water spotting from sprinklers is mineral deposit and will not wash off with detergent — it needs an acid descaler.
Cloudiness between the panes is a failed seal and cannot be cleaned from either side at all.