How to Use a Clay Bar on Glass Safely

Clay bars are often used on a car’s paint to remove contaminants like tar, tree sap, bugs, water marks and iron fallout, giving the paint a smooth and slick feeling. But is it safe to use a clay bar on glass to give it a deep clean?

In this article, I’ll explain exactly how to use a clay bar on glass safely and effectively to remove the grime that accumulates every time you drive it. So let’s get started.

The Quick Answer

It’s perfectly safe to use a clay bar on glass as long as you use plenty of lubrication such as a clay lubricant spray, or car shampoo and water. Then simply glide the clay bar across the glass in straight line motions, rinse the surface and dry.

Claying your windshield and exterior glass removes contamination like water spots, tree sap and bugs. This improves visibility and makes the windscreen wipers last longer.

Why You Should Use a Clay Bar on Your Windshield

Clay bars are super effective tools at for removing contaminants which settle on your car and bond to the surfaces.

Your car is exposed to various sources of contamination such as bird mess, tree sap, iron fallout, hard water heavy dirt. This is especially a problem if you drive it daily or store it outside.

These contaminants quickly bond to your car’s surface and cannot be removed with routine washing. The only way to get rid of them, is using a decontamination product, like a clay bar.

These sources of contamination are not just a problem on your car’s paint, but on every outer surface, including the glass.

Clay bars are a very easy, safe, and effective way to remove surface contamination and leave your glass looking and feeling squeaky clean. This has several benefits:

  • Your windshield wipers will last longer because they won’t be exposed to as much friction.
  • Cleaner glass = better visibility.
  • Clean glass just looks better!

How to Use a Clay Bar on Glass

So how do you actually use a clay bar on your glass then? Well, the process is basically the same as you would use on your paint. Here are the steps.

  1. Clean the glass using a glass cleaner or car shampoo (without wax).
  2. Make sure the windshield and windows are wet.
  3. Use a clay lubricant spray, or car shampoo to lubricate the surface.
  4. Knead the clay so it’s soft and flat.
  5. Glide the clay across the glass in straight motions making sure the surface is lubricated at all times.
  6. Keep checking the clay for contamination, when you see any dirt, fold it to expose a clean section.

It’s really that simple!

The main thing to remember, is to keep the glass lubricated at all times. You don’t want the clay to grab at the surface, instead it should slide smoothly. So don’t press very hard, light pressure is plenty.

Remember, that clay is abrasive, so if used without lubrication, can easily scratch your car.

This is less of an issue with glass compared to clear coat, because glass is much stronger, but you still need to keep it in mind.

Will a Clay Bar Remove Water Spots from Glass?

Clay is quite effective at safely removing water spots from glass. It usually removes stubborn water spots relatively easily. Just remember to use plenty of lubrication and a clean side of the clay bar. You only need to use light pressure, don’t scrub at the surface.

If the clay bar was unable to remove the water spots from your windshield or windows, then try using a water spot removing glass cleaner, or consider polishing the glass.

How Do You Know If the Glass Needs Claying?

It’s really easy to tell if your car’s windshield or windows need claying. Here’s how.

  1. Put your hand in a plastic sandwich bag.
  2. Make sure the glass is clean and dry.
  3. Glide your hand over the glass.
  4. If it feels rough, then contaminants are bonded to the surface and it needs claying.

It’s a really easy trick to try. Usually your hand isn’t sensitive enough to feel the contaminants, unless they are particularly bad, so the plastic bag trick can come in handy.

Usually, the windshield will need claying much more frequently than the rest of your car’s windows.

The windshield is exposed to much more contamination, since it’s at an angle so contaminants will easily settle on it. Also, it is far more exposed when driving than the rest of the glass.

Usually, I clay my car’s windshield every month in Winter, and every 1-2 months in Summer, depending on how bad the weather has been. The rest of the car’s glass get’s clayed every few months.

It definitely helps with visibility when driving, and it only takes a few minutes so it’s well worth doing!

Deep Cleaning the Windshield

Sometimes claying the windshield isn’t always enough to get it squeaky clean and free from contamination. That’s why I usually deep clean my car’s windshield every couple on months to make sure the visibility isn’t compromised. Here’s how I do it.

Clean the Glass

I’ll first start by washing the car as normal using a mild car shampoo that doesn’t contain any wax. My favourite is Bilt Hamber Auto Wash, you can check out┬áBilt Hamber Auto Wash on Amazon.Then I’ll dry the glass and use a glass cleaner to give it a more thorough clean.

Use a Clay Bar

The next thing I’ll do, is clay the glass using the steps described above. I’m always careful to use plenty of lubrication and keep checking the clay for dirt and folding it if needed.

My favourite clay bar is Bilt Hamber Soft Clay, it’s really well priced, and very effective. Plus you only need to use water as a lubricant to use it safely. Although I use car shampoo as well just as a precaution.

You can check out Bilt Hamber Soft Clay on Amazon.

Polish the Glass

The next thing I’ll do, is dry the glass using a microfiber towel, and then I’ll polish it. I use a dual-action machine polisher and a compound like Meguiar’s Ultimate Compound on a microfiber pad. It’s not designed specifically for glass, but I find it does a great job at getting the glass super clean.

Seal the Glass

The final thing I’ll do, is seal the glass to make the surface very hydrophobic so water beads off. It really helps to improve visibility when driving in the rain, and prevent contaminants bonding the surface.

I use a water-repellent glass cleaner called Vision by Auto-Glanz to do this, but you can use something like RainX or a ceramic coating if you want something more long lasting.

Maintaining the Glass

To maintain the glass between deep cleaning and claying, it’s important to use a glass cleaner and wash the windows weekly using a wax-less car shampoo and water. Then I’ll follow this by topping up the protection using the rain-repellent glass cleaner.

I find this really helps to keep the glass clean and prevents more contaminants bonding to the surface for longer, making the deep clean process a little easier and faster.

Thanks for reading! I hope you’ve found this article helpful. Don’t forget to check out the rest of the blog to learn more about making your car look its best.


I first became interested in car detailing around 3 years ago and learnt all the main techniques on my very first car. I spend a lot of time detailing my current car, and trying to keep my family's cars looking presentable too!

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