Smears and streaks on windows are mainly caused by watermarks and areas where cleaning solution has remained on the surface – this is down to excess moisture not being absorbed when wiped away. Window cleaning products will say that they are streak-free, but it is not that simple.
Use a Z-shaped motion on your glass panes
'Take a microfiber cloth and wipe in a Z-shaped motion to stop the smears and get every little,' they say. However, for more stubborn marks, you may need to dilute a mild detergent into the water.
Excessive Cleaning Solution
Whether you have purchased a premixed glass cleaner, or you are using your own soapy mixture, too much cleaning solution will cause streaky windows. It is a common misconception that the more cleaning solution you use, the cleaner the glass will be but with windows this is not the case.
Almost all windows have an insulated glass unit (IGU) inside of them. An IGU doubles the R-value of a glass window, increasing its energy efficiency. Foggy windows occur when the seal around the IGU begins to deteriorate. Over time, the seal around your insulated windows will begin to decline.
One of the most common reasons for glass to become foggy or cloudy is water damage. This can be from a leaky window, condensation, or even humidity in the air.
An easy-to-find product that you may already have in your cabinets, the acidic composition of white vinegar works efficiently to break down the film that can accumulate on your windows. For a basic vinegar cleaning solution, we recommend mixing one part distilled vinegar to 10 parts warm water in a spray bottle.
Outdoor wind can kick up dirt and dust, causing it to become airborne. This dirt and dust can then cling to window exteriors and makes them appear dirty.
Instead of using standard cleaning products, get a bucket of water and mix it with dishwashing detergent or vinegar. Apply this cleaning solution to the glass using a long window scrubber. Grab a squeegee and pull its blade over the glass in a reverse “S” pattern.
In a spray bottle, combine ¼ cup of white vinegar with ½ teaspoon of liquid dish soap. Dilute the solution with 2 cups of water, then shake the bottle vigorously to mix the components. If you don't have white vinegar on hand, you can substitute it with lemon juice.
If you wake up and find condensation on your bedroom windows, a great way to clear away the condensation is by mixing a home-made solution. Simply mix two cups of water and two cups of white vinegar, then add a couple of drops of washing up liquid.
You can use Windex® Ammonia-Free Glass Cleaner on your vehicle's tinted windows, mirrors, glass, chrome, stainless steel, plastic, and vinyl surfaces. For a streak-free shine, clean car windows when the surface is cool and out of direct sunlight whenever possible.
If the windows are particularly grimy use four or five drops of dishwashing liquid in a bucket of warm water. If you're happy with the result you can dry the windows, if you would like some extra sparkle, rinse the windows by adding two or three cups of vinegar to clean water.
So, whether you're out of your usual glass cleaner or you're just looking for a cheaper option, white vinegar can work wonders on your windows and mirrors. Mix it up with warm water (again, soft or distilled H20 for best results) at a 50/50 ratio.
This has to do with the evaporation rate—if your cleaning solution evaporates before you have time to wipe it off, it will leave a mark. Alcohol- and ammonia-based cleaners evaporate more quickly than vinegar, but any window cleaner can leave streaks if it isn't removed fast enough.
Ditch the Paper Towels
Paper towels may be a convenient drying cloth (they are disposable, they're cheap and they get the job done), but they tend to leave lint streaks across your windows and doors. If you want truly sparkling windows, opt for a microfiber cloth, chamois, or even newspaper to dry your windows.
Window cleaning spray (either a natural or commercial cleaner); or a bucket of hot, soapy water (washing up liquid is best). A clean, soft cloth (an old T-shirt or cotton sheet is fine) or scrunched-up newspaper, for polishing windows and making them sparkle. A big sponge, to apply the soapy water.
Frankly put, fogging happens when the seal between the two panes of glass wears down or fails totally. Once the seal fails, moisture is allowed to seep into the space between the two pieces of glass. In order to clean the fog, you will first have to remove the seal and then clean each piece of glass.
But condensation between the panes of glass means your windows are effectively broken and need to be fixed or, more likely, replaced, as fog is one of the many window problems that can indicate it's time for replacement.
Use vinegar
Mix two tablespoons of white vinegar to one cup of water and, either using a spray bottle or a paper towel, apply the solution to the glass. The acid within the vinegar will break down any cloudiness. It will also give a more sparkling finish to the glass.
Spray a stronger mix of 1:1 water and vinegar (or Windex, or glass cleaner) at your window, so that the solution covers most of the glass. (I found Windex to work better, but if you have pets—or kids—who frequently lick outdoor windows, vinegar may be the best route for you.)
Vinegar is great for cleaning glass, but because it's acidic, it can't be used on every surface.
Paper towels are typically treated for absorbency, which makes them ideal for spills, but awful for glass cleaning. Instead, substitute your paper towels for something more practical, like actual cloth. Lint-free cotton cloths, like microfiber cloths are great options for glass cleaners.