Window cleaning has always been a challenge for both detailers and car washes. It’s an area where customers demand perfection, but more often than not, they are dissatisfied with the look of their glass. We all try to provide streak-free and crystal-clear glass, but streaking remains a huge concern. In order to produce perfect windows every time, we need to understand the many variables that cause window streaks, have a good technique, and use quality cleaners and towels to produce perfect windows every time.



Streaks are caused by a number of things. Some are easily controlled. Some are not. Let’s take a look at the causes.

Below: A perfectly clean window will have clarity and gloss — whatever is inside shows up perfectly outside, and vice versa.

Window Cleaner

Many window cleaners contain a combination of ingredients that will clean, but may also cause steaks, including alcohol, ammonia, and detergents.
Depending on how fast or slow these ingredients evaporate, and how highly concentrated they are, streaking problems may occur. The residue from these ingredients sometimes dries and evaporates on the glass before your window towel can remove them. Window cleaners need to be properly diluted; more is not better. The higher the concentration level of the cleaner, the greater the possibility of streaking.

Once you have the correct dilution of window cleaner, and are sure the cleaner is not the source of streaking, other causes can be looked for.

Type of Towel

With so many types of towels available, it is very confusing as to which is best for window cleaning. You need a towel that is absorbent, lint free, and actually helps clean the glass. Many detailers still use terry cloth towels to clean windows, and unfortunately, they are not the best choice. Once terry cloth towels get too wet, they lose absorption, and will only spread the dirt and moisture around until it evaporates on its own, leaving the glass full of streaks. These towels also leave a tremendous amount of lint.

I have been searching for the best available window towel for years, and have yet to find the perfect one. However, your best choice is a microfiber towel with a waffle weave, or a 100percent cotton surgical towel. I use these in combination, which will be discussed later.


Contamination is another source of streaking and may come from a few sources. If you are using your “window” towels for any other purpose, they may be contaminated with other products. I have seen detailers use a towel to wipe excess tire dressing from wheels and use that exact same towel to clean windows — and they wonder why the windows aren’t coming out so well! Many detailers have towels dedicated to window cleaning only, but wash them along with towels that have been used to wipe up excess tire dressing, polish, or wax. All of this residue may contaminate window towels if they are washed together. Window towels need to be washed separately from other towels. It is also a good idea to run them through a second rinse cycle to fully wash away any contamination.


Above: The two towels needed for the job: the surgical or cleaning towel (left)
and the buffing or waffle weave microfiber towel (right).

Insufficient Cleaner

Many detailers simply do not use enough window cleaner.
They think that too much liquid will take too long to clean, or they are afraid to get their window towel too wet. Consequently, they use a small amount of cleaner and let the towel do the rest. The cleaner gets wiped up and dried too quickly, and the dirt is just pushed around the glass and not totally picked up, causing streaking.

Spraying Cleaner on the Towel

Many detailers spray the window cleaner directly on the towel. This is incorrect. By spraying the cleaner on the towel, you are letting the cleaner soak into the towel rather than have it soak into the dirt that is on the glass. Not enough product is used, which results in streaks.


Many detailers simply rush the entire process. They think the glass is fairly clean to begin with, so they give the glass a quick spritz, quickly run the
towel back and forth, and assume they have correctly cleaned the window. Being in a hurry also leads to poor technique, which further enhances the possibility of streaking



Some people think they have magic formulas for window cleaning such as special cleaners or towels. Others subscribe to the theory that you do not need a window cleaning “towel” at all. These folks used to use newspaper to clean windows with very good results. Newspaper is very absorbent and lint free, and is virtually cost-free and plentiful. When a piece gets too saturated, simply grab a new sheet. It seemed to work well. There is a logical reason for this. The newsprint — the ink used on the newspaper — used to be kerosene based. Kerosene is a terrific cleaner. It also does not evaporate very easily, and people used to simply spray some water on a glass surface, wipe it clean with newspaper, and produce streak-free windows. However, the ink in newspaper is no longer kerosene based, so newspaper simply is not as effective as it used to be. Although it is very absorbent, it’s very difficult to hold and get flat surfaces to wipe across the glass. You generally need to “scrunch” the newspaper up in your hand, which makes it very easy to miss certain spots, like corners. These missed spots can be streaks, or dirt and haze that never gets fully cleaned off the surface. Newspaper is not a good choice for a window cleaning “towel.”



Above: A correctly folded towel is flat and fits perfectly in your hand.

Before we talk about the correct towels to use, let’s make sure we know what towels not to use. Paper towels are not a good choice. They are absorbent, but many people continue to use the same piece even after its soaking wet. They also will leave a lot of lint. The same also holds true for napkins, tissues, old T-shirts, handkerchiefs, etc. We need to have the correct towels to do a great job

I use a combination of different towels. We all agree that microfiber is the best choice for cleaning. However, some microfiber towels do not absorb water very well, which is problematic in window cleaning. A regular microfiber towel tends to push the liquid around the glass and never absorbs it. You need a towel that not only will clean, but will also absorb. With that in mind, I use a surgical towel to perform the “cleaning” part of the process, and use a waffle weave microfiber towel as a “final buff,” to ensure any and all residue has been wiped off.


Right: Lower the glass a couple of inches and run the folded towel along the dirty upper part of the glass to ensure a perfect window.
Right: You need to get the glass wet with cleaner, but not so wet that it’s running down the glass.
Below: A perfectly folded towel makes it easier to get into every deep corner.
Right: Lower the glass a couple of inches and run the folded towel along the dirty upper part of the glass to ensure a perfect window.
Right: You need to get the glass wet with cleaner, but not so wet that it’s running down the glass.
Below: A perfectly folded towel makes it easier to get into every deep corner.

A surgical towel is 100 percent cotton, lint free, and absorbent, but also has some bite to it, and will dig in and clean the glass. The waffle weave microfiber towel is much more absorbent than regular microfiber, and will absorb any residual moisture and “buff” the glass clean.



The first thing to look for before cleaning windows is any glue residue from old decals or stickers on the glass. Use an older towel to remove the glue and keep your actual window towels clean. You never want any glue on your towels; it will smear all over the glass you are trying to clean.

There are some things that need to be done before you start to clean the glass. You need your towels nearby. You can’t spray the glass, walk around looking for a towel, take a phone call, have a drink, and then clean the glass. It just won’t work.
You need to be ready to go.

Next, the towel needs to be folded correctly to perform its job. Most towels are approximately 16 by 16 inches. If you fold it across twice, you will have an 8×8 towel, which fits perfectly in your hand and will give you a good cushion, be more absorbent, and allow you to easily maneuver the towel around the glass.



My “cleaning” window towel is the surgical towel. My “buffing” window towel is the waffle weave micro fiber that will finish off and “buff” the glass.

My towels are pre-folded and ready to go. I spray the window cleaner directly on the glass to wet and emulsify the dirt and haze that has accumulated. The cleaner should cover almost all of the glass, but not start to run down the surface. Immediately after spraying the glass, I clean it with my “cleaning” window towel. First you want to box out the area and cover all four corners of the glass and really make sure the towel gets into those tight corners. Then you want to overlap your stokes by about 50 percent in either a back and forth or up and down motion and cover the entire surface. You do not want to move in a circular direction because areas may be missed.

If your cleaning towel starts to get too dirty or too wet, open up the folded towel and use a fresher side. There is no need to wipe the window totally dry with this towel. With a little moisture still left on the glass, quickly switch to your “buffing” towel to absorb and buff the remaining moisture. This process may seem like extra work, but it ensures that the glass will be streak free.



Your choice of which window to start with is totally arbitrary, but I do have an opinion and hopefully a logical explanation of where to begin.

I begin with the front windshield. This is a fairly difficult glass to clean on most vehicles because of the very pronounced slope on many of today’s cars. I prefer to start with the most difficult glass first. Plus, I know my towels are fresh and clean and this gives me the best chance at producing a streak free finish. This is the most important piece of glass to clean; the customer is constantly looking out of the front windshield. If you mess this glass up, the customer most certainly will notice and will most likely start to look for other problems.

Next, I do the rear windshield because it’s the second most looked through window, and also a very difficult piece of glass to clean. Many times you will have to contort your body to reach the tight areas in the interior, while also being careful not to hit the glass with your sweaty forearms. We all know the feeling of try-ing to clean a hot and difficult interior on a sweltering summer day. One wrong move with your sweaty arms will mean doing that part of the glass all over again. Take your time and get it right! Don’t rush! Being in a huge hurry is a leading cause of streaks. You must be able to expertly navigate around the third brake light housing and reach the towel as deep into the rear shelf as possible to get that film at the very bottom of the rear windshield.

Once the very challenging front and rear windshields are cleaned, I can now stand back up, get out of the car and clean the side glass. Do not forget to lower the side glass down an inch or two to expose the upper lips of the glass. This generally is a very dirty area. After cleaning the upper lips of all the glass, I will most likely have to throw my “cleaning” towel in the wash basket. It’s now pretty wet and dirty and I do not want to risk re-depositing that dirt back onto the glass. So I simply discard that “cleaning” towel and introduce a new one to clean all the side glass. My “buffing” towel should not get too wet or dirty, and can stay in play.



After all the glass is completed, look for streaks. It is better that you find them rather than the customer. Examine the glass from different angles both inside and out and look for streaks. A perfect window will look like there is no window there at all.

As you can see, window cleaning is a little more involved than it looks. Many customers will base their decision to continue using your services on the cleanliness of their windows. Don’t let this often overlooked problem drive customers away.


Kevin Farrell owns and operates Kleen Car (, a full- service auto-detailing business located in New Milford, NJ. Kevin is also an instructor for a detailing program he developed for, and in conjunction with, BMW of North America. His background includes auto dealership experience and training through DuPont, General Motors, and I-Car.

Kevin Farrell is the owner of Kleen Car Auto Appearance. He can be contacted at 888.302.6400.