My laptop screen is scratched

The screen on my IBM Thinkpad X31 has a long scratch (about 20mm) one of its bottom corners. The cause? My cat, pawing the screen to chase the mouse pointer as I was working (okay, playing with the cat). The scratch doesn’t appear to be too deep, but it does distort the display beneath it, although this seems to be as a result of some kind of optical effect rather than more serious damage to the screen itself. A friend suggested using toothpaste to buff out the scratch, much like using T-Cut to repair car bodywork, but I’m sceptical. Have you got any better ideas?

Wendy Baddock, Plymouth

The outermost layer of a laptop's TFT screen is made from plastic, which makes repairing scratches tricky. In theory, your friend's suggestion of using toothpaste is sound: toothpaste is a mild abrasive, which is why it's useful for cleaning the surfaces of our teeth. It's far too abrasive to 'buff out' a scratched plastic surface, though, and the large, uneven particles would turn the scratch into a foggy mess.

You can buy products designed to buff scratches out of plastic. Many users rate Displex Display Polish (£3 plus P&P) highly, but you can get the same results with Brasso. Just dab a lint-free cloth on the Brasso wadding (don't use the wadding itself!) and patiently polish out the scratch. Sadly, Displex and Brasso work only on glossy screens, whereas the Thinkpad X31 has a matte finish. Try polishing it and you'll make it worse.

The optical effect you've noticed is the result of a change in the screen's optical qualities. That top layer of plastic is a polarising filter, which means the light passing through the scratched area isn't polarised. One trick is to carefully fill the scratch with petroleum jelly ( Vaseline, or similar). Apply it with a cocktail stick and wipe off the excess with a soft cloth in a swift motion. Petroleum jelly is closer to the refractive index of the screen than air is, so it often does a good job of making the scratch less noticeable.

Laptop screen protectors are available (similar to those available for PDAs), but we were unable to find a supplier in the UK. US supplier Nushield will ship to the UK though. Finally, a piece of chamois leather or soft, lint-free cloth cut to fit over the keyboard will protect the screen if the lid gets pressed down while a laptop is in transit.

Solution 1 Polishing

Brasso is a cheap fix for a lightly scratched glossy screen. Dab a soft, lint-free cloth on to the Brasso wadding, then use the cloth to polish the scratched part of the screen. Brasso is abrasive and, with care and patience, will restore the shine to glossy plastic.

Solution 2 Filling

You can't polish out a deep scratch, but you can reduce its visibility by filling it with petroleum jelly. Clean the screen, then use a cocktail stick to fill the scratch with jelly. Wipe off the excess with one swift motion of a lint-free cloth - any other method may wipe jelly over the screen, or out of the scratch.

Solution 3 Prevention

You can protect a laptop screen while the lid is closed by cutting a rectangle of chamois leather or other soft, lint-free material to fit over the keyboard. Leave it in position when you close the lid, and it will protect the screen from marks and scratches from the keyboard and pointing device.