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

Clay bars can be used on glass, including the windshield. Make sure to wash the glass using car shampoo first and then use plenty of lubrication in the form of a clay lubricant spray, or car shampoo to glide the clay bar across the glass in straight line motions, then 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.

Looking for some of the best decontamination products? Make sure you check out my recommended products page for all my current top picks.

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.
  7. Rinse and dry the glass as normal.

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.

Make sure you check out my guide to the best clay bar lubricants to make sure you choose the right option to minimise any marring and swirls that may be inflicted by the clay.

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

Will a Clay Bar Remove Water Spots from Glass?

Clay is reasonably 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 dedicated water spot remover spray, 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.

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.

Wash the Glass

I’ll first start by washing the car as normal using a mild car shampoo that doesn’t contain any wax. Then I’ll rinse the shampoo away.

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.

Rinse and Dry the Glass

This ensures all the contaminants have been flushed away and that the surface is ready for the next step.

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 either a dual-action machine polisher with a foam pad, or a hand foam polishing pad and a glass polish like CarPro Ceriglass to make sure the glass is completely clean before applying protection.

Coat the Glass

The final thing I’ll do, is apply a coating 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.

Two of my favourite glass coatings are the Pyramid Car Care Carbon Glass Coating and Soft99 Ultra Glaco Coating.

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-free car shampoo and water. Then I’ll follow this by topping up the protection every few weeks using a rain-repellent glass cleaner such a Soft99 Glaco De 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.



Heather is a professional car detailer & valeter based in Cheshire and the owner of Auto Care HQ. A familiar face in the car detailing community, she has written over 200 car detailing guides on and has produced over 165 videos on the Auto Care HQ YouTube channel.

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