A clear windscreen is an essential part of safe motoring, but scratches and chips are a part of life. Is there anything you can do to fix them though? Let’s find out.
Why Scratched Windows Are a Problem
There are plenty of reasons behind scratched windows in your car, from stones and other debris kicked up on the road, to wiper blade scratches when something gets stuck between the rubber and glass. They’re all annoying, but some can cause bigger problems over time.
Windscreen glass is toughened and laminated with vinyl at the factory, so it’s strong enough to withstand heavy impacts, but it’s still prone to gouges and scratches that can distract you when you drive and obscure the view of the road ahead.
The real danger of a scratched windscreen is if the scratch is allowed to become a crack. Once your windscreen is cracked, the structure of it is compromised and can weaken your car during a collision. You might not know it, but your windshield contributes to the structural strength of your car, especially if you roll over.
A crack in your windshield will grow over time and is affected by temperature changes inside and outside of your car. Jumping in your car on a winter’s morning and turning the blowers up to de-mist your screen can transform a tiny crack into a huge one that runs across the entire windscreen in seconds.
A damaged windscreen isn’t just a safety problem either- if the police pull you over with a crack obscuring the driver’s side you could get three points on your licence or a hefty fine. And if you’re involved in an accident you could get the blame for driving a vehicle in a dangerous condition.
Can I Fix It Myself?
If you want to save yourself the time, effort and cost of replacing your whole windscreen, the good news is that there are good kits out there for repairing scratches. But you must be realistic when it comes to repairing anything bigger than a little chip or scratch. There’s a point when replacement is the only sensible solution to a damaged windscreen.
The first thing to look for is if the chip or scratch is in what’s known as a critical area– this is defined as the part of the window that you use for “necessary observations” during driving or if it’s within the sweep of the windscreen wiper blades.
Inside of the critical area, scratches or chips that you can feel with your fingernail and are larger than 10 mm are not suitable for DIY repair. Outside of this critical area, you can try and repair damage up to 40 mm long because it won’t affect your MOT test.
If you’re in doubt, it’s probably best to consult a trusted windscreen repair company, but don’t be put off a home repair if you think the damage isn’t too bad and you’re confident enough to attempt it yourself. Some light scratches can be fixed with specialist polishes, but chips and deeper scratches need an application of glass resin.
If you’re confident you can fix that scratch yourself, you’ll need a few things to get the job done right:
- A microfibre cloth
- Isopropyl alcohol, sometimes sold as surgical spirit
- A piece of dark paper or card
- Masking tape
- A windscreen repair kit, sold online and at good car repair shops
Windscreen repair kits are widely available and aren’t expensive if you shop around. The contents vary but you can expect to find the following items:
- A bottle of glass resin to fill in the scratch or chip
- A sticky seal that acts as a barrier around the damage, for when you pour the resin
- A resin chamber that holds the glass resin in place during application
- A syringe that forces the resin into the crack or scratch
- A sharp pin to remove glass shards or debris from the damaged area
- A razor blade to scrape clean the glass before and after the repair
- A curing strip made of clear plastic
If there’s one thing we think is important if you’re going to attempt a DIY windscreen repair, it’s the preparation stage. Your glass can’t be too clean before using your kit and using a bit of card will help to see the damage more clearly.
Clean your windscreen with a microfibre cloth and isopropyl alcohol thoroughly in a circular motion to remove any dust, grit or oils around the damage. Avoid spraying alcohol into the crack or scratch though as it can react with the glass resin. Always add the cleaning solution to the cloth.
Use your razor blade to carefully scrape the area around the damage to remove any fine dust or dirt. You’ll be surprised at what you can remove but be careful not to scratch it even more!
Use your masking tape to attach a piece of card to the inside of your windscreen where the damage is. The contrast will help to show up the crack or scratch better and make the repair easier to do.
The instructions that come with your windscreen repair kit should be followed carefully, but a general guide to repairing your windscreen will go like this:
- Use your pin to remove any bits of glass from the scratch or chip
- Attach the sticky seal to where the chip is located
- Attach the resin chamber to the seal and pour in some of the glass resin
- Use the syringe to force the resin into the damage
- Allow the resin to cure for 5-6 minutes
- Remove the seal and wipe of any excess resin
- Attach the curing strip and leave in direct sunlight where UV rays will harden the resin
Fixing Long Windscreen Wiper Scratches
If you’ve got a long scratch in your windscreen caused by grit becoming stuck in your windscreen wipers, and you can’t feel the scratch with your fingernail, you might be able to polish it out.
Windscreen polishing kits almost always contain polishing pads and some sort of polishing compound made with cerium oxide, otherwise known as “opticians rouge”. It’s a rare-earth metal that helps grind off the jagged edges of scratches without blurring the surface afterwards.
You’d need to use an electric drill to apply it with enough speed for it to work properly, and getting the right pressure and can be an art in itself, but it’s worth trying out if you’re confident with power tools.
Our top tip is to try and keep the drill as straight as possible when polishing, and to keep it moving to avoid over-polishing one spot and overheating the glass. In extreme cases, overheated glass can delaminate and shatter.
Maintaining Your Windscreen
You can’t prevent stone chips and scratches on your windscreen unless you keep your car locked in a garage and never drive it. But you can do a few things to help avoid unnecessary damage:
- Clean your windscreen wipers regularly to keep them free of grit and dust
- Change your windscreen wipers before they wear out
- Keep your windscreen washer fluid topped up
- Clean your windscreen with a car glass cleaner to remove grit regularly
- Never let your windscreen wipers run on dry glass
- Don’t ignore tiny scratches that can become bigger ones over time