Some months back, one Kars4Kids spouse asked if we knew how to get the filmy gunk off the inside of his windshield. He’d tried all sorts of cleaning fluids and cleaning techniques and nothing worked. Also, he couldn’t figure out how his window got all filmed up in the first place and wondered what we knew about that.

He came to the right place. After all, we are the car people, right?

Right.

So about that gunk on your windshield, what it is, is gasses that are released from all the plastics in your car as it heats up. According to Meteorologist Jan Null, of No Heatstroke:

The atmosphere and the windows of a car are relatively “transparent” to the sun’s shortwave radiation and are warmed little. However this shortwave energy does heat objects that it strikes. For example, a dark dashboard, steering wheel or seat temperatures often are in the range of 180 to over 200 degrees F.

These objects (e.g., dashboard, steering wheel, childseat) heat the adjacent air by conduction and convection and also give off longwave radiation which is very efficient at warming the air trapped inside a vehicle.

Null writes about this stuff to warn people about the dangers of leaving children in cars, something we’ve tried to warn about, too. But while not as important as alerting people to the risk factors for hot car deaths, the heat that builds up inside your car can film up your windshield, and make visibility difficult. That too is a danger to you, your passengers, and other people on the road.

So we’re going to tell you how to clean it. It’s a TNT (tried and true) method. Just don’t take any shortcuts, and you’ll be amazed at how well it works. Your windshield will be as clear as, well, glass.

Interior Windshield Cleaning Method:

1. Begin by making sure your car is in the shade and that it’s a relatively cool day. First thing in the morning is a good time to do this, before the car has a chance to heat up.
2. Fill a bucket with warm water and enough liquid dish soap to make it sudsy.
3. Take a sponge, dip it in the sudsy water, squeeze it out, and go over the inside of your windshield, dipping it into the bucket, and squeezing it out, after every few passes.
4. Now this is the important part: rinse the windshield twice, with clear, fresh water. Rinse it really well.
5. Rub the glass dry with a clean towel. Old towels are the most absorbent and highly recommended for cleaning jobs.
6. If you still see streaks, you didn’t do a good job, and there is still plastic residue on your windshield. Repeat steps 3, 4, and 5.