CD Mastering and Audio Mastering

Let's start with the basics of handling and caring for optical discs. Most of these are common sense but it never hurts to mention them as reminders. Optical discs should be handled by the outer edge or through the center hole. Discs should not be bent or flexed and only write on the clear hub of the disc and use a water based felt-tip permanent marker.

Always keep discs that are not being used in a jewel case or some type of sleeve (paper or plastic). Jewel cases are the preferred method for storage because they are supported at the hub. Never stack discs so that they are touching each other to prevent scratches and to prevent warping due to excess weight. Also store jewel cases vertically (like a book) instead of horizontally which leads to unwanted stacking of CD's.

Lastly if a disc is dirty, dusty or smudged with fingerprints you may be able to clean it before it is permanently damaged. With dust, use a non-abrasive photographic lens tissue, or very soft brush. Fingerprints can possibly be removed by using a DVD/CD cleaning agent or isopropyl alcohol. Use only small quantities and make sure the cleaning motion is from the center of the disc outwards to the edge.

Posted by Brian at 06:33 PM | Permalink

As most of you are well aware of, all optical discs, need a little TLC when it comes to handling. Even the smallest scratch can cause significant amounts of data loss. There are a variety of sources that can lead to the damage of discs. The first one to mention are those lovely little scratches that interfere with the light path that makes it difficult to read optically. These scratches or surface deposits can cause skipping or a track to repeat itself. Even fingerprints can cause surface damage that is irreversible. Certain inks that are typically used for printing on the surface, mostly for labels, can ruin or corrode the plastic or lacquer layer and sometimes even the metal layer. The last thing to keep in mind, which is easy to forget or to even think about, is the effect that humidity and temperature can have which causes degradation. Next week we will give some pointers on how to clean discs and how to protect your optical discs from further damage.

Posted by Brian at 09:48 PM | Permalink

There are several types of discs used to store information that are read optically (hence the term) by a laser. Technically there are only three main types of optical discs that we will be talking about. First are the ROM discs, either CD-ROM or DVD-ROM, where the information on the discs is 'read-only memory' (ROM) and therefore cannot be changed or added to by the end user. The second type of discs are WORM or 'write once-read many' discs, better known as read-write optical discs. The most common type of worm discs are the CD-R's (recordable) discs that can be recorded on only once. The last optical discs to mention are the rewritable discs. The most common forms of the rewritable discs are CD-RW and DVD-RW which are used when information will be revised, edited or updated on a regular basis.

Optical discs are made from a polycarbonate plastic base comprised of 3, 4 or 5 layers which includes a metal layer usually made of aluminum, silver or gold. The data that is stored on the disc is created by making marks or pits using lasers. These pits or marks are then read by a laser through absorbing or reflecting the light. These attributes are most common for the ROM discs. For CD-R's a photosensitive dye layer is added between the polycarbonate and metal layers to capture and store data. The technology for the rewritable discs involves adding a phase-changing film between the polycarbonate and metal layers. This film gets heated by the laser beam which changes its light transmission properties therefore making it possible to erase and rewrite data. Check back in a few days to read part 2 on Optical Discs.

Posted by Brian at 10:16 PM | Permalink