DIY: Plastic window repair - Step by step

Get rid of pesky scratches and marks with this quick and easy project!

Words by Ian Pedley

Our drive is a bit tight and, reversing the caravan in, I must have touched one of the concrete fence posts with the offside rear window, putting a six-inch set of deep scratches along the middle of it. I’ve been too upset to mention it earlier.

Browsing through the local Halfords, I came across a promising-looking repair kit from Autoglym. The kit is actually for renovating road-blasted plastic headlights, but I thought I’d give it a go on my poor window. The kit costs around £27 and contains everything you need to carry out a perfect repair on a plastic window.

Following the kit instructions carefully, I took my time with my first effort, but I reckon you could repair a badly scratched window in about 30 minutes tops with a bit of practice. No pressure!

This would also include removing any surface scratches caused by those inevitable tree branches. I reckon the kit would be good for another five similar-sized windows, i.e. the whole caravan.

The unit illustrated is a Dometic side window and a good tip when using the coarser grit is keep checking the surface temperature of the window. If too much heat is allowed to build up this can damage the window, so don’t let it get hot.

Have a look at my before and after pictures to see the results.

Tools and materials

• Autoglym Headlight
• Restoration kit (£27 from Halfords)
• A cordless drill
• Pozidriv and Torx screwdrivers (to remove the window from the vehicle and dismantle the catches and stays)
• Water spray bottle
• Eye protection
• Soft base cloth for the bench
• Soapy water and a clean cloth

Top tip

There’s a great video (by Autoglym) that tells you exactly how to do it. Watch it below. 

Step-by-step guide to repairing a plastic window

1. These were the offending nasty scratches the concrete fence post had inflicted on my poor caravan.

2. To make the Dometic window easier to repair it needs to be removed. Start on the inside by unscrewing the Torx screws holding on the catches and stays.

3. Outside, lift the window up to expose the end cap screw – this needs to be removed by using a Pozidriv screwdriver.

4. After undoing this screw, the whole window can be slid out along its sliding hinge and removed from the vehicle more easily.

5. Slide the window out of the top channel until the whole unit is freed – put it down on a soft cloth on your workbench to protect it.

6. The repair kit has everything you need in it, including suitable liquid, a drill pad base, various grades of abrasive paper, a foam pad and a microfibre cloth.

7. I started with the coarse 800 grit disc fitted to the rotary pad and concentrated on the scratched area. I took it easy and monitored any heat build-up.

8. I did this until I couldn’t feel the scratches and then switched to the 1500 grit discs and repeated the process. I gradually worked through to the fine 2000 grit abrasive disc.

9. Once this felt smooth, I then switched to the finest 3000 grit abrasive pads. The final stage is to give the whole window a good buffing with the liquid polish.

10. The results speak for themselves – good as new! If you’re not happy with the end result, simply repeat the process until you are happy.