Disc cleaning picMy mate Ross is a fellow movie buff and he lately bought a film he’s been chasing for months through an Italian website, a delightfully quirky and original tale about Beethoven’s ninth symphony called Lezione Ventuno, or Lesson 21. It took some weeks to turn up and he was appalled when, just 15 minutes in, the picture froze, then pixelated. And then the DVD player closed down entirely.

There was nothing for it, he concluded, but to send the disc back and wait patiently for a replacement. Italy being Italy, the replacement was unlikely to arrive anytime soon. If at all.

But I achieved instant hero status by fixing it for him in less than two minutes. He even gave me a free beer. All it needed was a clean.

Ross, like most buyers of DVDs and CDs, had assumed that a brand new disc straight out of the case would be clean, but that’s not my experience at all. I’ve found so many brand new discs wearing all sorts of laser-confusing lint and micro-grit that I now clean every new disc I buy prior to the first playing as a matter of course.

Rented movies are far worse. They’re so frequently pock marked with scratches and finger prints that it’s a wonder they play at all, especially in new generation Blu-ray players which are proving to be rather fastidious beasts.

The message here is that if and when you strike a disc that starts giving problems, try cleaning it first. My experience suggests that nine times out of ten it will fix the problem.

Ah, but this being home entertainment, cleaning an optical disc is of course not as easy as it sounds. Nope, effective cleaning is an art. Do it the wrong way – and almost everyone does it the wrong way – and you can wind up making things worse by damaging the playing surface.

To understand this you must first think like a disc player.

The data path in the disc, a seriously narrow little line of pits and ridges that is read by the player’s laser, spirals around the disc just like the groove in an old LP record, except that while the LP’s groove goes from the outside to the centre, an optical disc’s data stream starts at the centre and works its way to the rim.

Now when optical discs were first designed their creators figured they would pick up dust and scratches, so they built a tolerance into the technology for such things. When the laser strikes a scratch or a speck of dust its error-correction circuitry kicks in and carries it over the problem and back to the data stream, all with no break in the program for you.

But error correction goes only so far and a major break in the data can cause the program to jump, skip, repeat, freeze, pixelate, return to the start or close down entirely. This is a long way of saying that while disc players can usually tolerate a scratch that runs at right angles to the data stream, causing a mere blip in transmission, one that run along it and therefore brings a prolonged break in the data can render the disc unplayable.

This is what you have to think about when you’re cleaning the disc. Clean it in a circular motion, around and around the disc, and you could leave tiny scratches that run in line with the data stream. Disaster.

The way to clean the disc is to move your cleaning cloth from the centre hole straight out to the rim and then back again, gradually moving around the entire playing surface. If you leave any micro scratches they’ll thus be at right angles to the data stream and won’t cause problems. Well, no problems that the player can’t handle anyway.

There are plenty of decent mechanical disc cleaners on the market that clean discs exactly like this. Most are operated with a hand crank and they do an entirely acceptable job, but the best result you’ll get is cleaning by hand using an optical cleaning solution (optometrists and chemists sell it for cleaning glasses) and a lint-free cloth. I got a ripper from Enjo.

Don’t use tissues – they often leave more lint than they remove.

One last point: While you should always ensure that the playing surface of the disc is pristine don’t, repeat do not, clean the label surface. This side of the disc is extremely vulnerable to damage and the underside of the data stream is located just under the label. If you scratch or hole the label you’ll almost certainly render the disc unplayable. Forever. There’s no way to fix it.

So if there’s anything sticky, or stuck onto the label surface the best bet is to leave it there, because any attempt to remove it could well bring the label with it.

If you’re into buying second-hand discs always hold them up to a strong light before handing over the cash. If you can detect any holes in the label at all steer clear.

Published September 2009