I Clean Houses For A Living. Streaks Are Not A Cleaner Problem. They’re A Drying Problem.

every october somebody asks me to do their windows before winter, and every october i have the same conversation on the way in. they have tried four glass cleaners. and the glass still dries with streaks in exactly the same places.

i own a cleaning company in western new york and i have done a genuinely stupid number of windows. so here is the thing nobody says in the aisle: a streak is not a cleaning failure. a streak is a drying failure.

glass is nonporous. there is nothing for dirt to soak into. whatever is on it is sitting on top, and almost anything will lift it. which means the product is close to the least important part of this, and the part everybody is spending money on.

what a streak actually is

two things, and they are both about water leaving.

the first is residue. you spray, the liquid starts evaporating immediately, and whatever was dissolved in it gets left behind in the pattern the liquid dried in. that pattern is the streak. it is not dirt you missed. it is the map of how the water went.

the second is that most people use about four times as much product as the job needs. more cleaner does not mean cleaner glass — it means more dissolved stuff left behind, and a film that attracts dust, so the window looks worse in a week than before you started.

which is why the single biggest improvement most people can make is free: stop doing windows in direct sun. on a sunny wall the glass is hot and the liquid is gone before your cloth gets there. you are not cleaning, you are racing evaporation, and evaporation wins. do the sunny side early or late, or on an overcast day, which in october here is most of them.

the order i actually work in

dry first. a dry pass with a cloth takes off dust, cobwebs and the loose film, and if you skip it you are just making mud and then spreading the mud around. this is also where most of the apparent dirt lives.

then product, and not much of it. i use a foaming glass cleaner — foam because it stays where you put it instead of running down into the frame and drying there, which is its own streak two inches from the bottom of every pane.

then the part that does the actual work. flat microfiber cloths, bought out of the automotive aisle rather than the cleaning aisle, because it is the same cloth in packs of fifty instead of packs of six. flat, not waffle-weave: a waffle texture leaves a waffle pattern, and you will stand there wondering why. one cloth damp, one cloth dry, and the dry one is the one that decides what the window looks like.

and if you want one tool that makes it faster rather than better, it is a squeegee. i have not worn this exact one out myself — that is the category talking — but the mechanism is not controversial: a squeegee removes the water in one pass instead of pushing it around, which is the whole problem. overlap each pull by an inch and wipe the blade between pulls, because a squeegee with grit on the blade draws a line down the glass and you will blame the glass.

there is one place paper genuinely wins, and that is a final buff on a small pane where lint does not matter and i do not want another cloth in the wash. the strong cloth-like kind is the only paper towel i buy, because the cheap ones shed fibers onto wet glass and that is a different kind of streak that looks exactly like the first kind.

and newspaper does not work better than a cloth. it worked better than the cloths people had in 1974.

the spots that are not dirt

hard little specks that survive everything — paint flecks, sticker adhesive, overspray from whoever did the trim — are physical objects and need a physical tool. a razor scraper takes them off in seconds, and the rules are: only on glass, only wet, brand new blade, shallow angle, one direction. a dry or dull blade will scratch, and a scratch on glass is permanent. never on a coated pane, never on a mirror.

and if the glass is cloudy in a way that does not improve no matter what you do, go and wet it. if the cloudiness disappears while it is wet and returns as it dries, that is mineral deposit and it comes off. if it stays cloudy while it is wet, the water has etched into the surface and there is nothing left on top to remove. i wrote the whole test out in the post about hard water on glass, because it is the difference between a cleaning job and a window you are going to have to replace eventually, and it takes thirty seconds to find out which one you have.

the frames, which are where the dirt actually is

nobody has ever called me about a dirty window frame and everybody has one. the sill, the track, and the weep holes at the bottom of the track that let water out — those pack with dust, pollen and three years of grit, and then the water that was supposed to drain sits in the track instead. in a wny winter that is where you get condensation, then mildew on the inside of the frame, then a conversation about the wood.

vacuum the track first, then a damp cloth and a general multi-surface cleaner, and poke the weep holes clear with something soft. that is ten minutes per window and it is the part that actually prevents something.

and give the cleaner a minute before you wipe it. that is true of everything in the cabinet and it is the one habit that separates a professional from a person with the same bottle — i went on about it at length in the post about why spraying and wiping is not cleaning.

the outside, and how to not do this again in march

outside glass is a different job because the dirt is weather. rinse first, work bottom to top so the dirty runoff lands on glass you have not done yet, and dry top to bottom.

and then the thing that buys you a season: a water repellent, sold for shower glass and windshields and the same chemistry either way. it is a coating, not a cleaner, so it needs clean dry glass and the cure time on the bottle before anything wet touches it — on dirty glass you have sealed the dirt under a coating. a category pick rather than something i have run for years, and the honest version of the claim is that water sheets off instead of beading and drying in place. fewer spots, not no spots.

one safety line and i mean it. a lot of glass cleaners contain ammonia. ammonia and bleach make chloramine gas. so do not do a window and then a bathroom with the same bucket, and never spray one over the other because the first one did not seem to be working. one chemistry per pass, with water in between.

and the upstairs outside panes: i do those from inside where the window tilts, or i do not do them. a ladder on wet october grass is not a cleaning decision, it is an emergency room decision, and i say that as somebody whose actual job this is.

the whole thing, short

not in the sun. dry pass first. less product than you think. two cloths, one damp and one dry. squeegee if you want it quick. and the frames, which nobody does and which is the half that stops something rotting.

you were never bad at this. you were drying wrong, which is a much easier thing to fix than a personality.

and if your cloths come out of the wash smelling faintly of a basement, that is not the cloths, that is the machine, and it has its own post.

Some of the product links in this post are affiliate links, which means I get a small commission if you buy through them, at no extra cost to you. The glass cleaner, the microfiber, the paper towels, the scraper and the multi-surface cleaner are what I actually buy for work. The squeegee and the water repellent are category picks rather than things I have personally worn out, and I have flagged both of those in the text where they come up.