Keeping the outside of our windshield clean is a habit most of us picked up when we learned how to drive. Whether you clean your windshield at home, or when you fill up at a gas station, you understand why good visibility is important to your overall driving safety.

But when was the last time you cleaned the inside of your windshield and the other glass surfaces in your car? You may think that these areas don't need cleaning, because they aren't directly exposed to dirt, dust, precipitation, road salt, tar, bird droppings, and squashed insects.

The reality is that the inside of your windshield can get just as dirty as the outside - but from different causes. The things that can build up on the inside of your windshield and other glass surfaces can seriously impair your vision outward - and that is a huge hazard.

Join us for an insider's view of the reasons why the inside of your windshield gets dirty, the tools and materials you need to clean the inside of your windshield properly and safely, step-by-step instructions on how to do it right, some do's and don'ts for cleaning the inside of your windshield, and finally, some tips on how to keep the inside of your windshield in good, clean condition.

Why the inside of your windshield gets dirty

The inside of your windshield can become dirty from many different causes, but there is one source that is the major contributor. It's the various plastic materials that are used to make your vehicle's interior. After the plastics in your door panels, dashboard, console, and seats (if they are covered in vinyl) are assembled at the factory and sealed into your interior, they begin a years-long process of emitting vapors.

These vapors are what new car buyers have come to know and love as "that new car smell." The plastics inside your car will continue to emit these vapors, long after the new car smell is gone. This is known as "off-gassing" and the process steadily deposits a film that adheres to the glass interior surfaces of your car. If it is not regularly cleaned from your glass, this oily, hazy coating builds up and becomes very difficult to see through. It can impair your vision during the day when the sun hits it, and at night when you are facing the glare of oncoming headlights.

Off-gassing leads to streaky windshields and increased glare.

There are some other things that can make the inside of your windshield dirty. They are:

    • Kids' fingerprints on the glass
    • Your dog's saliva and smudged nose prints
    • Cigarette and cigar smoking inside your car
    • Dust and dirt from the air outside your car

Whatever the causes may be, you will improve your outward vision as well as make driving safer by regularly cleaning the inside of your windshield and other auto glass.

The tools and materials you need to clean the inside of your windshield

Having the right tools for the job, before you get started, makes the complete process a lot easier and free from hassles. Here's what you need to get the job done right:

    • A pad for scrubbing that's safe to use on glass (do not use steel wool or other harsh materials)
    • An adequate supply of clean microfiber towels
    • Window cleaners (both foam and spray-on types) made specifically for use on glass (nothing with ammonia, and no all-purpose cleaners)
    • A tool for reaching into and cleaning the corners of your windshield (not necessary, but it makes the job much easier!)

A note about home-made cleaning solutions: There are many recipes out there for glass-cleaning solutions that claim to be better than what you can find on store shelves. Some use vinegar, some use dish washing liquid, some use rubbing alcohol, and some use ammonia. If you want to try any of these, be careful, especially when mixing chemicals together.

There are some other issues to consider. The smell of vinegar will linger, and it will take a while to leave your car. Ammonia (or any window-cleaning product with ammonia in it) is a bad idea because it leaves streaks behind. It can also damage the non-glass materials in your car's interior, such as vinyl, leather, and aftermarket window tinting film.

Items to avoid when cleaning the inside of your windshield

Here are a few things not to use when cleaning the inside of your windshield:

Household towels: The towels from your linen closet should not be used to clean the inside of your windshield - or any other part of your car. They will scratch the surface, and these towels will also leave unsightly lint behind. Use only microfiber towels that you keep separate for car-cleaning duty only. And when you wash them, never use fabric softener or bleach. Dry them on the lowest setting or let them air dry.

Sponges: Using a sponge to clean the inside of your windshield may seem to make sense, but it's a bad idea. Sponges are designed for scrubbing, and they will have an abrasive effect on your glass. Sponges will also pick up and hold tiny bits of dirt and grime, turning themselves into sandpaper. Leave your sponges in the kitchen sink where they belong - keep them far away from your car!

Step-by-step guide to cleaning the inside of your windshield

Have everything ready to go? Before you start, be sure that you are parked in a shaded place where the windshield and other glass surfaces are cool to the touch. Why? Hot glass is uncomfortable to work with. It will also cause your cleaning products to evaporate too quickly. Let's go!

1. Prepare your dashboard

Take some microfiber towels and cover the top of your dashboard. Doing this will keep your glass cleaner from getting onto the dash as you clean the inside of your windshield.

2.  Get your scrubbing pad ready

Take your spray-type glass cleaner and spray some on your scrubber to prime it. Pick a corner of the windshield to start with and hit this area with a few sprays of glass cleaner.

3. Start scrubbing

Using firm, even strokes, scrub firmly but gently, from top to bottom. The film on the inside of your windshield will resist, but your scrubber should be able to break it up and loosen it.

4. Use a microfiber towel to wipe away the residue

When you have broken up the film with your scrubber, your microfiber towel should take the residue right off. Spray some glass cleaner on the towel and wipe it using both horizontal and vertical motion. To be sure that you are using a consistently clean surface of your towel, turn your towel regularly - or switch to new one when it's full of the residue.

5. Time for some buffing

Take a fresh, clean microfiber towel and wipe any remaining residue or glass cleaner away. If you have a reach tool, it can be helpful for getting into tight spots. For additional cleaning power, wrap the towel around the reach tool while using it. Once that you have this first corner clean, repeat the above four steps at each of the remaining corners.

6. Upgrade your shine to the next level

We will now switch from our spray-type glass cleaner to the foam cleaner. Why? The spray worked great for priming the scrubbing pad and our towels, and for getting the film residue off. The foam cleaner gives you more time to work, better control, and a nicer-looking finish. First, spray a line of the foam cleaner from one side of your windshield to the other, about a third of the way down from the top edge.

7. Start at the top and work your way down

Using a microfiber towel or your reach tool, clean the entire surface of the inside of your windshield. Wipe in both directions (horizontal and vertical) and don't miss a spot.

8. Inspect your job carefully

Step outside your vehicle and look through your windshield from several different angles, trying to spot any film residue you may have missed. It may help to move your car so that the sun is shining directly through the windshield. This will highlight any hazy spots remaining. Go back and re-clean any spots you may have missed. Nice job!

The dos and don'ts of cleaning the inside of your windshield

Let's recap some key points about what you should and shouldn't do when cleaning the inside of your windshield:

Use a suitable glass cleaner for your windshield.

You should always:

    • Use good-quality glass-cleaning products made specifically for automotive glass
    • Use a scrubbing pad that won't damage the windshield
    • Use clean, dry microfiber towels for cleaning and drying your windshield
    • Cover your dashboard with microfiber towels to protect it from the cleaning products
    • Switch to a new cleaning towel when the one you're using gets dirty
    • Wipe in horizontal and vertical strokes
    • Continue until your windshield is completely clean and dry

You should never:

    • Use all-purpose cleaners
    • Use glass cleaner with ammonia
    • Use abrasive scouring pads
    • Use household towels
    • Use sponges
    • Wipe in circular strokes

Tips for keeping your windshield clean

The process that produces the off-gassing haze on your windshield works much faster when your car's interior is heated up, or when the sun is shining directly into it. This annoying film is produced even faster when your interior is sealed up tight. To slow down the effects of off-gassing, do what you can to keep your car's interior as cool as possible, such as:

    • When you park, crack your windows (when possible)
    • Place your car in a shady spot (but not under a tree!)
    • Get a sunshade for your windshield
    • Cover your car with a car cover
    • Use a garage or a carport whenever you can

If your windshield is getting dirty from other common causes, you can try these solutions:

    • Stop smoking, or don't allow it in your car
    • Restrain your pets
    • Clean your kids' fingerprints off the glass regularly