TDK has produced a scratch proof DVD coating and is making big claims for its ability to protect disks from day-to-day wear.

Anybody hearing whistles, clicks and repeated track segments from scratched CDs will know what this means, and that's before you consider the image breakup that comes from damaged DVDs. The coating has to protect the surface of optical disks but let the reading laserbeam shine through and receive its reflections unaltered.

Even higher-capacity DVDs are coming, with higher-capacity still Blu-ray and HD-DVD fighting it out for the post-DVD standard. The consequences of scratches in the disks' coatings become more severe in terms of data loss as the same size scratch spoils more and more data.

TDK has invented a new polymer coating. Disks using it are called Armor Plated and TDK is already selling 8cm Armor Plated DVDs for DVD camcorders. It says they are the 'most damage-resistant recordable DVD disks available.' The polymer coating includes protection against ultra violet ray damage, three times better than existing coatings, according to TDK. The company says that it provides '100x greater scratch resistance than standard DVD media' according to its lab tests.

The new coating is less than 0.1mm thick. In a filing with the US patent office it appears that the coating is spun onto the disk in two layers. One layer protects against scratches and the second against contaminating fluids. A second generation coating technology will be used to protect Blu-ray disks.

The coating has a very hard surface which makes it much more resistant to contamination by dirt, fluids and fingerprints, as well as impacts from hard and sharp objects - such as fingernails, table edges and all the other hard edges a dropped DVD can encounter. DVDs left out of their cases will be much better able to survive food and drink spills. The disks' recording layer is protected from these contaminants and so the disk will be much less likely to exhibit write/read errors, jitter and playback dropouts.

The coating also repels dust because it is anti-static. Notmal DVDs release 50 percent of an electrostatic charge after 15 hours. The TDK-coated disks release 50 percent in 50 minutes. So they attract far less dust.

It sounds as if this coating could be useful for graffiti-ridden surfaces too, like bus and train windows and painted surfaces.

A TDK product manager, Rich Martino, said , "We'ev even tried to scratch them with steel wool pads and write on them with permanent ink markers - and the disks wouldn't scratch, while the marker ink came right off." An independent tester reported that marker ink need nail polisher remover to get it off; also that Brillo pads could mark the disks if enough muscle was used.

In practice, disks coated with this TDK polymer will be able to withstand the normal wear and tear of DVD player and case insertion and removal much better than standard DVDs.

With Blu-ray disks the 25GB recording layer is closer to the surface than with the rival 25GB-a-layer HD-DVD format. So Blu-ray can use a stronger protective coating. HD-DVD disks are only going to be as resistant to damage as current DVDs.

Following on from TDK's coating advance HP has said it will produce PCs equipped with Blu-ray disks next year. Dell is also a fellow Blu-ray supporter alongside HP. THe Blu-ray consortium has endorsed the coating.

Although DVD rental life is only 12-15 cycles due to scratch accumulation rendering the disks unsatisfactory TDK is concentrating on the Blu-ray market.

TDK estimates street prices for DVD-R Armor Plated disks will be $5.99 (£3.75 at straight conversion rate). Average prices for ordinary DVD-Rs are around $1 so you have to pay for the better protection.