Will a Clay Bar Remove Water Spots on Glass?

A clay bar will remove water spots on glass if they’re sitting on the surface, but it won’t remove any that have etched into the glass. The easiest way to tell is to clay the glass first. If the water spots come off, they were sitting on the surface. If you can still see or feel them after claying, more claying won’t take them off.

What Water Spots on Glass Are

Water spots are mostly calcium and magnesium mineral deposits left behind on the glass when hard water dries. Hard water is water that’s high in those minerals. In many areas, it’s what comes out of the tap, the hose, and the sprinklers.

Rain leaves water spots on glass too, because of the dust and pollution it carries and anything it picks up as it runs off a roof or a tree.

There are two types of water spots:

• On top: The minerals are sitting on the surface of the glass. A wash removes the lighter ones, and a clay bar lifts the rest.
• Etched in: The minerals have eaten into the glass itself. Clay can’t reach these, and only polishing takes them off.

Etching happens when the sun bakes the minerals on until they eat into the glass, and the longer they sit, the worse they get. Once water spots are etched in, washing won’t take them off, and the glass stays streaky no matter how many times it’s wiped.

How to Tell If Clay Will Work

First, think about how long the water spots have been there. If it’s the first time you’ve noticed them, clay will usually take them off. If the glass has had that spotty, streaky look for weeks or longer, they’re most likely etched.

Also check the glass in the sun or under a light. Etched glass isn’t noticeable in the shade, but once light hits it, it’s much more obvious.

How to Clay Bar Your Windshield and Car Windows

1. Clean the glass: Work in the shade with the glass cool to the touch. Clean it with a glass cleaner and a microfiber towel to remove loose dirt before claying.
2. Lube the section: Spray plenty of clay lube on the section of glass you’re working on. A rinseless wash solution or wash foam works too.

3. Clay the section: Glide a mild clay bar across the section side to side, without pressing down hard or going in circles.

4. Wipe and check: Wipe the section with a clean microfiber towel and run your hand over it. If it’s smooth, move on to the next section. If it’s still rough, fold the clay to a clean side and clay it again.
5. Clean the glass again: Once the glass is done, clean it with a glass cleaner to remove any leftover lube.

At any point, if the clay drops on the ground, throw it out. It picks up sand and small rocks that can scratch the glass.

What to Do When the Clay Doesn’t Take the Water Spots Off

Start with the gentlest option, and if it doesn’t work, move on to the next one.

1. Diluted white vinegar: Vinegar breaks down minerals that are bonded too firmly for the clay to lift, but it won’t fix etching. Mix white vinegar and water 1:1 in a spray bottle. Out of direct sun, spray it onto the glass and a microfiber towel, wipe it over the water spots, then rinse the glass with water.
2. Acid water spot remover: These are acid-based and made to dissolve minerals, so they’re very strong. Test the remover on a small section first, wear gloves, and keep it off the paint and trim. Put it on a damp microfiber towel instead of spraying the glass, wipe it over the water spots for a minute or two, then rinse it off. Don’t let it dry on the glass, or it can leave the glass permanently cloudy.
3. Glass polish by hand: Apply a generous amount of glass polish to a microfiber towel. Rub it into the glass with firm pressure, one small section at a time, then wipe it off and check the glass.
4. Glass polish by machine: This step is more advanced and is best left to a professional detailer. Tape off the trim around the glass and test a small section first. Then work the glass polish in with a machine polisher and a glass polishing pad. Start the machine at a low speed and increase it as you go. Wipe it off and check the glass.
5. Replacement: Some etching goes too deep to polish out. When that happens, the glass needs to be replaced.

Protecting Your Glass

Right after claying is the best time to protect your car’s glass. Once it’s clean, put on a glass sealant, a ceramic glass coating, or a rain repellent. These products are hydrophobic, which means they repel water. Water beads up and rolls off the windshield instead of sitting on the glass, which makes it much harder for water spots to form.

Keeping Water Spots Off Your Glass

• Dry it right away: Don’t let water air dry on the glass.
• Park in the garage: It keeps the car away from sprinklers and out of the rain and sun.
• Wash with deionized water: If you wash at home, a deionized water system takes the minerals out of the water, so it’s less likely to leave hard water spots.

FAQs

Does a clay bar remove water spots on paint?

Yes, if they’re sitting on the surface of the clear coat. Clay can’t remove water spots that have etched into the paint, and those have to be polished out, the same as on glass.

Can water spots be permanent on glass?

Not usually. A glass polish removes etched water spots, and only very deep etching means replacing the glass.

How often should you clay your windshield?

Only when it needs it. Claying glass isn’t regular maintenance like washing your car. Use a clay bar when you notice water spots or streaking, or when the glass feels rough to the touch.

Will a clay towel or clay mitt remove water spots?

Yes, if the water spots are sitting on the surface. Like a clay bar, they can’t fix etched water spots.

Can you use soapy water as clay lube on glass?

Yes, as long as you use plenty of it.

Will a clay bar remove scratches from a windshield?

No. A clay bar can’t remove scratches. Depending on how deep they are, the scratches either have to be polished out or the glass has to be replaced.

Final Thoughts

A clay bar is the first step for water spots on glass. It removes the ones sitting on the surface. If any water spots are still there after claying, they’re most likely etched in and will need to be polished out.

If you’d rather have us handle it, contact us at Grandeur Autos in Calgary, and we’ll clay your glass and tell you exactly what it needs.