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Ultimate guide to Clean a Windshield

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If I’m honest, most of us detailers absolutely hate having to clean a windshield. There is no end to the pain and suffering that the window will put you through. Just when you think you’re done, there it is, another streak or foggy blotch. Who doesn’t want that crystal clear view? Free of debris, film, or spots leftover. There is no greater feeling than getting into your car and looking through that streak and smudge-free glass.

You know when you take your sweet ride through the gas station car wash and the dryer doesn’t quite get all of the water spots? Or when your partner puts their bare feet on the window leaving oily toe smudges? Or how about when you just quickly use Windex and a good old-fashioned paper towel only to find debris and remnants, and again, that fog? Yeah, we need to graduate from this level of so-called clean. This guide will help enthusiasts break this cycle and hopefully make your journey of cleaning a windshield a little easier.

What to Expect

Let’s start by setting expectations here. Cleaning windows to perfection is tedious work; there is no way around it. The outside can have water spots and the devil’s juice: tree sap. Of course, there’s the inside, with its inevitable buildup of film and ‘gunk’ that occurs naturally over time. It happens to all of us.

Although window cleaning is tedious and daunting, it doesn’t have to be. This window cleaning guide for dummies answers all your problems. Follow along, and I will steer you into a whole new world where the streaks and buildup no longer fog your vision. I will take you to the land of crystal clear visions.

How to clean the outside of the windshield

For the outside of the windows, I usually run into three things:

  • Plant material (tree sap)
  • water spots,
  • animal-based material (bugs/bird droppings).

You must remove the tree sap before doing anything else to the window.

Water stains on care windshield
Water stains and built-up debris

Tree Sap Removal

I use a solvent such as Kerosene or lighter fluid for tree sap. You can use nail polish remover or acetone, but I find that it evaporates quickly and takes a few passes. The less volatile solvents give you more working time. Rubbing alcohol doesn’t always do the trick either. Of course, there are over-the-counter bug and sap removers that you could use as well. Try not to get it on the paint or plastic for it may damage it.

I highly recommend using the over the counter bug and tar removers first before going to more extreme chemicals such as kerosene or acetone. These will attack the paint depending on dwell time and temperature and paint type. Old school 1K paint will melt with those chemicals. Modern 2k paint is more resilient. Use at your own risk.

Water Spots

For water spots, I find myself using Chemical Guys Water Spot Remover. If you follow the instructions on the bottle, it will usually do the trick. It does have a pungent vinegar smell which makes me think they are using acetic acid to dissolve the alkaline water spot. After using this product, wash the window one last time to remove any leftover chemical residue. Try to not get it on your paint and if you do rinse it off thoroughly. I generally wash the car after doing the windows if the spots were really bad.

For light water spots you can use a vinegar blend and some of the better window cleaners I have used include this in the formulation. Here is an example of a window cleaner with a vinegar blend.

Insects and Bird Droppings

Window cleaner and elbow grease usually gets it off 95% of the time. If it is really bad, you can use a plastic scraper or lay a sopping wet towel over it for a few minutes to soften it up. There is a bug brush which is one of my favorites to run over the front bumper and window during the wash portion. It is a bit un-nerving to use at first but it hasn’t scratched the paint on any of my cars.

Cleaning the windshield

Once you have taken care of any water spots or sap, go ahead and spray a window cleaner on the microfiber and wipe in a circular motion. Flip the towel and wipe one last time to dry any wet spots.

Next, you want to use a clay bar. Spray the window down with water or clay lube and clay the front window. Remember to massage the clay bar and fold to expose fresh clay surfaces. The clay will break loose the contaminates that are fixed.

Using a Clay Bar on Car Windshield
Using a clay bar to remove contaminates

After claying the window, spray the window cleaner on and wipe it up with a new microfiber towel. Flip it and dry with the other side of the towel.

Steel wool on the windshield

Use at your own risk. Some people use 0000-grade steel wool to clean the outside of their windows. Do not use 000 or coarser steel wool; this may scratch your window. Additionally, always test an inconspicuous corner of the window before moving forward with the rest of the window. 0000 steel wool has a Mohs hardness just under glass to remove most things bonded to the glass without scratching it. Always check first, I have heard horror stories of scratched windows. Also you can scratch and scuff the paint and plastic near the window edges, so there is that risk as well.

Sealing and protecting the outside of the windshield

The final step for the outside of the windshield is to use a wax sealant or spray sealant to coat the window. This will improve the water beading off the window in the rain and the performance of the wiper blades. In addition to this, it will make the dirt come off easier next time you go to clean the window.

Using a Sealant on Car Windshield
Finish off with a sealant

How to clean the Inside of the Windshield

Cleaning the inside of the window can be a little easier since you won’t have to deal with sap or water spots. But the dash in the way does not make it very easy. There are tools that can help with this. Start by using a fresh, clean microfiber and wipe the inside of the window. Nothing on the towel, just a dry microfiber cloth. This will remove most of the film from the window and hold it into the rag. You can flip to a fresh side and rerun it to get a little more off. Finally, use a liquid to remove the rest of the contaminants. You can use a window cleaner but be sure to follow it up with another clean damp rag to wipe off the cleaner residue.

Tip to cleaning the tight spaces inside the windshield

A foam block such as a magic eraser can easily get in the tight spaces between the window and the dash. I like to set the foam and wipe the window down. Then follow up with a dry microfiber wrapped around a rigid piece of flat plastic.

clean a windshield
Foam makes it easier to get the inside corners of the window.

Sealing the inside of the window for easy cleaning later

Finally, finish the window by spraying a sealant compatible with glass, wipe it on with a new microfiber, and buff off with another fresh microfiber. This will help remove the remaining streaks and make it easier to wipe down in the future. 

Keep in mind that the cleanliness of your towel will play a significant role in how clean your window is. Tip, if the dash is greased up with a protectant and you drop the towel on it, then wipe the window, it will probably leave streaks. So be careful to not let the towel make contact with anything that could be transferred to the window. I recommend leaving the new microfibers in a clean bag and pulling it out when you are ready to use them.

Looking for a guide on what to use to protect the windshield then check out this guide.

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