How to Clean Glass Without Streaks

Everyone Loves Crystal Clear Streak Free Glass

One of the most annoying things about cleaning glass is how to clean the glass without leaving any streaks?  Glass streaks have to be the number one problem people, including professional car detailers struggle with when cleaning glass. 

The way to not get streaks when cleaning windows is actually really simple.  The answer is so simple, once you read my two tips below where I explain the best way to clean windows without leaving streaks or smears, it will all make perfect sense. 

What is a streak?

A streak on glass is simply some unwanted substance that has been smeared over the glass after you have wiped the glass.  It is simply a residue of some form.

Cleaning car glass without streaks comes down to 2 simple tips or best practices.  Besides sharing these 2 tips I will also share how to troubleshoot what the problem is when it comes to glass streaks and how to fix the problem. 

Tip #1 – Use a great glass cleaner

Of course, on its face, this tip not only makes sense but you’re probably thinking, duh, I already knew this.  But knowing this and purchasing a quality or great glass cleaner are two different things.  Most people think glass cleaners are simple products and for the most part, they’re all the same.  But just like there’s a HUGE difference in abrasive technology used in compounds, polishes, and cleaner/waxes, (something I type and talk a lot about in the car detailing world), there’s also a HUGE difference in the quality or chemical make-up of glass cleaners on the market.

Tip #2 – Use LOTS of microfiber towels

This is where most people make their glass cleaning mistake.  Let explain WHY this is just as important if not more important than using a great glass cleaner. 

When cleaning glass, whatever the dirt, smudge or film is on the glass that you’re trying to remove – IF you are successful at removing it – where is it now?  It’s on the towel.  And this is exactly what you wanted – you wanted the substance you’re trying to remove off the glass onto the towel.

And from this point forward – STOP USING THIS TOWEL

If you continue to use this towel – you’re simply going to re-introduce the substance, which can be, dirt, fingerprints, pet slobber, vinyl fog, smoker’s film and/or any other smudges or streaks deposited by whatever has touched the glass in the past. 

And this is the biggest mistake people make including seasoned, professional car detailers.  The problem is called cross-contamination.  This means, taking the offending streak, smear, or film off one section of glass and transferring to a new section of glass.  When you do this, you see streaks and smears and it drives you up the wall.  In essence, you’re not fighting the glass – you’re fighting yourself. 

The answer to the problem is to have plenty of clean, microfiber towels on hand to clean all the glass on the inside and outside of your car so you can avoid cross contamination.

What supplies do you need?

So now that we know what the problem is – below are products and solutions you can put into your new glass cleaning regimen and completely avoid streaks and smears on both the inside and outside glass on your car, truck or sports utility vehicle.

First, you need a great glass cleaner

What makes for a great glass cleaner?  That’s a great question!  A great glass cleaner is formulated to do 2 primary things,

1: Cleans well

In this context, clean means DISSOLVES.  The films, streaks, smears, fingerprints, pet slobber, dirt, etc., that builds up on both the inside and outside of the glass for your car is some form of substance that is either water soluble or water insoluble.  If a film or substance you want to remove is water insoluble, this means the glass cleaner needs some type of solvent so that it can dissolve the water insoluble film or substance. 

Thus, a smart chemist understands this and creates a glass cleaning formula that can dissolve both water soluble and water-insoluble substances at the same time. 

3D is a genuine manufacturer and their staff of in-house chemists, including the owner, create all our formulas at our laboratory in Santa Clarita, California.  Our 3D Glass Cleaner is formulated to clean a wide spectrum of all the common substances found on both the outside and the inside of the glass.  

We also offer our glass cleaner in multiple forms as we cater to the enthusiast car owner, (do-it-yourselfer), professional detailers, car dealerships, commercial car washes and collision shops.  You can purchase a 16-ounce bottle of ready-to-use glass cleaner or if you do volume work, we also offer our class cleaner as a glass cleaner concentrate that you can dilute to suit your needs while saving money by purchasing in bulk. 

2: Evaporate at a controlled rate

When a chemist creates a glass cleaner, they must create a formula that offers a good balance between remaining wet on the surface long enough for you to work the cleaner over a section of glass or an entire window, while at the same time formulate the liquids to evaporate or flash-off the surface so at some point you get to dry glass.

Use a microfiber towels to wipe glass

When it comes to cleaning glass, people have tried all types of cleaning cloths and even unconventional materials to crack the secret to streak-free glass.  Conventional materials include cotton towels, t-shirts, and cloth rags.  Unconventional materials include things like old newspapers and paper towels.  All of these things will work but none of them will ever work as well as the miracle cloths called microfiber towels.

Why do microfiber towels work so well compared to other options?

It’s all in the name and the two different dynamics involved with the physical make-up of this type of cloth.  

The name – microfiber

As the name implies, the fibers that make-up microfiber are microscopic in size.  This means you have hundreds of more tiny fibers moving over the surface as compared to traditional fibers.  More fibers mean more surface area to grab and hold onto the dirt, oily films, and other substances you’re trying to remove off the glass.

Two dynamic characteristics of microfiber

The fibers that make-up microfiber excel at two things, adsorbing and absorbing. 

Adsorbing means to wick onto itself.

Absorbing means to wick into itself.

Other fibers do this too, but not to the effectiveness and thoroughness that microfiber does then when rubbed over glass. 

Which type of microfiber towels work best?

In real simple terms, there are two types of microfiber towels, fluffy towels, and flat weave towels.  Yes, I know there’s a lot more to all the hundreds of variations of microfiber towels on the market, but I wrote – in real simple terms.  When it comes to cleaning glass windows and avoiding streaks, not only do you want a microfiber towel that pulls or wipes streaks and other substances off the glass, but you also don’t want a towel that leaves itself and by this, I mean you don’t want a towel that leave LINT behind on the glass.  This can be just as annoying as glass streaks. 

So, a microfiber towel with a flat weave, or a short, closed nap or loop works best for cleaning glass.  Microfiber towels that are fluffy, especially microfiber towels with a long, open strand of fiber inherently are more prone to leave lint behind.  So, choose a microfiber towel with a flat weave or short pile, closed loop design. 

How often should you clean your car windows

There is no standard answer except to clean your car’s windows anytime they need it.  The outside glass gets washed anytime you wash your car as well as a type of natural wash when it rains.  As for the inside, this is solely at your discretion.  A good rule of thumb is to clean the inside glass windows at least once a year, more often if needed.  People with brand new cars or people that smoke tend to need to clean the inside glass more often for two reasons, Vinyl Fog, and Smoker’s Film. 

Vinyl Fog

Vinyl Fog is the oily residue that builds up all surfaces on the inside of a new car including the glass when all the NEW vinyl, plastic, rubber and other artificially manufactured parts, fabrics, foam, insulation, etc. outgas or give off fumes.  The thing about vinyl fog is that you only see it on the glass but think about it?  When all these new components outgas the fumes are touching all of the inside of the car, not just the glass.  It's just your eyes only see it on the glass.

Smoker's Film

Smoker's Film is the oily residue in the smoke exhaled by the smoker that coats everything with an oily film.  The smoke from cigarettes contains carcinogens.  My guess is the smoker's film created by the build-up of cigarette smoke also contains carcinogens.  When cleaning smoker’s film off of window glass it might be a good idea to wear protective nitrile gloves.

Wash your windows inside and out starting with the outside glass first

When it comes to cleaning your glass and removing streaks or preventing streaks, here’s a good best practice, wash or clean the outside glass FIRST and then clean the inside glass second. 

Here’s why.  It’s easier to clean the outside glass, this is the first and simple reason why to clean the outside glass first.  The other great reason is because it’s easier to clean the outside glass it’s easier to ensure they are streak-free.  When you know the outside of the glass is clean and streak free, it makes it easier to troubleshoot where the problem is if there are streaks on the glass after cleaning the inside. 

Prep your car first

While glass is extremely hard, (I teach two kinds of glass polishing in my car detailing classes, topical and sub-surface glass polishing, so I know a thing or two about glass), it can still be accidentally scratched if there’s some form of hard, sharp abrasive contaminants on the glass.  

To prep your car for glass cleaning, it’s a good idea to wash the outside first as this is where any accumulation of contamination is the most likely to occur.   The most common causes of contamination that can cause scratches in glass are air-blown beach sand.  

I live along the Florida coast and have also lived along the Oregon coast.  Beach sand can easily become air-borne in the wind and deposited onto the tops of your wiper blades.  Then when you turn the wipers on, usually in the morning to clear morning due, the beach sand that has accumulated on the tops of the wiper blades is dragged over the glass where it leaves wiper marks or scratches.  

Other causes of scratches on the outside glass are like beach sand only in the form of industrial pollution that becomes airborne and deposited on your glass.  I’ve worked in machine shops where welding and grinding of steel and other metal takes place and the metal dust created from grinding can and does become airborne.  So, if you live or work and park your car in an industrial work area, this can be a real issue. 

For the inside scratching the glass is not normally a problem because the kind of contamination that can cause scratches doesn’t normally get on the glass on the inside of a car.  The most common cause of scratches on inside glass happens to older cars as the window slide brackets wear out enabling the glass to drag against the inner door wall structures.  

Tips and techniques for cleaning your car’s glass

1: Swap to a fresh, clean dry microfiber towel often

As shared at the beginning of this article, the two most important factors for avoiding window streaks on the glass on your car is to use a quality glass cleaner and use lots of towels instead of one or two towels.  The reason is because after removing any fingerprints, vinyl fog, smoker’s film etc., off the glass and onto the towel – if you continue to use the towel, you’ll simply move the contamination off one window and put it on the next window.  In essence – you’re fighting yourself.  So don’t do this, use plenty of towels.

2: Clean the outside of the glass first.

As stated above, the outside glass is simply easier to clean and this is key to ensure glass is streak-free on both sides.  Thus, after cleaning both the outside and the inside glass, if there are any streaks, it’s easier to determine which side of the glass has the streaks, (usually the inside), and thus remove the streaks by working on the correct side of the glass thus you avoid wasting time.

3: Sit in the passenger seat when cleaning the inside of the windshield

Due to the steering wheel being in the way of you reaching the inside of the windshield, it’s physically easier for you to clean both sides of the glass by sitting in the passenger side and then reaching over to the driver’s side area of glass than visa-versa.  Also be careful not to accidentally bump the rearview mirror potentially causing harm.

4: When cleaning the inside – spray the glass cleaner on the towel

To avoid getting glass cleaner overspray onto nearby surfaces like the dash and inside pillars, instead of spraying the glass cleaner directly onto the inside of glass spray the glass cleaner onto the microfiber towel instead.  This avoids glass cleaner overspray on nearby non-glass surfaces, which avoids any extra clean-up and just as important, removes the risk of staining other surfaces that could be more delicate and easily stained.  For example, a lot of cars are now incorporating microsuede into the interior.  My own car has microsuede on the pillars on the sides of the windshield glass and also the headliner.

5: Make your finishing wipes side-to-side on the outside of the windshield

This is a technique professional detailers use to determine which side of the glass has streaks – if any.  If you’re finishing wipes on the outside are side-to-side and the finishing wipes on the inside are up-and-down, then if you see a streak running up and down the glass you know it’s on the inside and not the outside.

6: Make your finishing wipes up-and-down on the inside of the windshield

Some people wonder why to use up-and-down wiping motion on the inside instead of the outside and the reason why is because when you’re inside a tight, awkward, and cramped interior compartment, it’s a LOT more difficult to move your hand over the entire width of the windshield.  It’s a LOT easier to move your hand over the entire height of the windshield starting on the driver’s side and finishing on the passenger side.

7: Roll the windows down to clean the window lip

Over time, the lip or edge of glass at the top of a window that rolls up and down can get an accumulation or build-up of the gasket material bonded or impacted onto this area of glass.  When cleaning windows that roll down, be sure to put the window halfway down and clean this section of glass.

8: Clean the tops of the window gaskets where the top of the window glass seats

To avoid having the top edge or lip of side windows get a stain of gasket material build-up, with the windows down, gently clean the inside of the window gasket at the top of the window frame with a microfiber towel and an all-purpose-cleaner.

9: Avoid window cleaners with ammonia

Many household glass cleaners contain a small amount of ammonia for a host of good reasons for household use but should be avoided for use on automotive glass.  Besides having a foul odor, ammonia could potentially stain delicate surfaces found on the inside of a car like the leather, vinyl, and plastic surfaces. 

 Ammonia stains window tint

While I’ve never seen any verified documentation that yes, glass cleaners with ammonia can stain window tinting film, why take a chance?  Stick with glass cleaners that state they are ammonia-free and safe for tinted windows. 

Besides these reasons, a well-formulated automotive glass cleaner is more than sufficient for cleaning glass without the need for ammonia. 

10: Clean windows out of direct sunlight

Just like you don’t want to wash your car in direct sunlight, for the same reasons you don’t want to clean your car’s glass in direct sunlight.  Sunlight brings with it heat and the sun rays and the heat they create cause liquids, for example car wash solution and glass cleaner, to dry prematurely leaving a film on the surface.  When possible, clean your car’s glass out of direct sunlight, for example in the shade or inside your garage.

12: Don’t forget missed areas of glass

Side mirrors

Review mirror

Vanity mirrors

Glass display screens

Sunroof and Panoramic glass roofs

Exterior camera lenses

13: Only wash glass towels with other glass towels

When a microfiber towel is brand new it has maximum adsorption and absorption, and this makes cleaning glass streak-free easier and faster.  If you wash your glass microfiber towels with other towels, for example the towels you use to remove car wax, because car wax is water insoluble, it’s more difficult to wash the wax out of and off the towel.  This makes the towel less absorbent and adsorbent, and this means using these towels in the future will make getting glass crystal clear and streak-free more difficult and time consuming.

14: Use a dedicated microfiber laundry detergent

The reason everyone LOVE microfiber is because it’s so soft and plush.  The way you maintain this softness and plushness is to use a microfiber towel laundry soap that is formulated to clean without making your microfiber towels crunch or hard.  I’ve been in the car detailing business for over 30 years and one of the things I’ve noticed is how popular the 3D Towel Klean is among a very very diverse demographic market – that says something about the performance of the product. 

Here at 3d in Stuart, Florida we wash all our microfiber towels using 3D Towel Klean and they remain soft and plush over repeated use and washing.  For an in-depth how-to article on how to wash your microfiber towels, check out my article below.

How To Wash Microfiber Towels & Mitts Correctly

Additional Information: 

Heavy duty glass cleaning

Sometimes you can have a build-up of some form of contamination on the outside of the glass that a liquid glass cleaner simply will not remove.  For cases like these, you want to use a glass-safe polish and polish the glass to remove the film. 

Water spots – Traffic Film – Drizzle stains

The water in our world is polluted.  Doesn’t matter where you live or if you use city water or well water, there are dissolved minerals and other forms of chemical pollution in our water supplies.  Over time, this dissolved contamination builds-up on the outside of your car’s glass and no amount of any brand of liquid glass cleaner will remove the film.

Glass Polishing

There are two kinds of glass polishing, 

  • Topical Glass Polishing
  • Sub-surface Glass Polishing

    1: Topical Glass Polishing

    This type of glass polishing is where you remove water spots, traffic film, also called road film, drizzle stains and other forms of surface contamination off the surface of the glass.  For the most part, any compound or polish that is clearcoat safe is also glass safe and will remove the contamination off the glass.  3D offers multiple options for compounds and polishes, and they can all be safely used to hand or machine polish glass.

    2: Sub-surface Glass Polishing

    This type of glass polishing can only be done by machine using rayon glass polishing pads and a special Rare Earth Mineral called Cerium Oxide.  3D is launching a brand-new Cerium Oxide Glass Polish that works exceedingly well compared to other brands.  I have personally tested this new glass polish formula and helped to dial-in how it performs and I’m happy to say it works better than any other cerium oxide-based glass polish I’ve ever used.  Stay tuned for a future article on how to remove wiper marks, water spot etchings, pits, swirls, and scratches here on the 3D website.  

    If put the two tips I’ve shared in this article into practice, you can completely avoid glass streaks and glass smears on both the inside and outside of your car’s windshield, and side glass windows, plus sunroofs, side mirrors and things like the vanity mirrors inside your car.  These tips will also help you to have streak-free glass on the inside and outside of your home, including glass windows and mirrors and glass cabinets.  Same hold true for RV’s, Boats and really… anything with glass.

    Final thoughts…

    If you have any questions or need help with any of your detailing projects, shoot me an email, I’m always happy to help. 


    Mike Phillips

    Reviews (1 comment)

    • Elaina D'Agostino On

      Thanks for the advice about using glass-safe polish to remove contamination that liquid cleaners can’t remove. There are pigeons outside the shop, and they can dirty the exterior part of the glass we will install. Knowing how to clean it will help us so much in the future.

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