Precautions when Handling CD-R
Let's think about the disc structure and recording mechanism for CD-R before taking any precautions.

CD-Audio and CD-ROM(both named CD below), and CD-R have little difference in their structure. On one side of a 1.2mm thick transparent plastic disc substrate, a recording layer is formed with the reflective layer and the outermost protective layer. Ordinary CD and CD-R disc structures have labels printed on top of the protective layer. The total thickness of the protective layer plus the reflective layer is only about 5μm(:5/1000mm), immediately below which lies a recording layer. It is very important to avoid scratches and smudges not only on the plastic substrate side (CD-R has green, yellow and blue dyes on this side, named below as the "recording side") but also on the protective layer side (usually called the "label side").

The major difference between these two discs lies in their recording layers. The CD has their recording pits formed during the molding process as embossments, while the CD-R has their recording marks laser-written onto a thin uniform dye recording layer only by the CD-R drive. CD-R drives naturally use a laser beam to record the blank CD-R discs (unrecorded discs are often called "blank discs"), therefore, more special care is required to handle the blank CD-R than to handle the recorded CD-R. Recorded CD-R discs can be handled with basically the same care as that required for CD.

Based on what has been described above on CD-R structure and recording mechanism, more concrete details of precautions on handling CD-R will follow below.

Operation and Storage Environments
The disc should never be exposed to high temperature humidity nor to low temperature and low humidity. Avoid exposure and to direct sunlight.
Although environments we face in daily life pose no serious problems for the operation and storage of CD-R, air-conditioning of the sites is preferable, of which temperature of 15-25°C and a relative humidity of 40-60% are recommended. (The illustration, left, shows 15-25°C and of 40-60% R.H. as "recommended CD-R storage environment.")
Precautions before Recording
Avoid smudging the recording side (substrate side)
Avoid touching or getting dust or fingerprints on the recording side of the CD-R as much as possible. Should the disc get smudged by accident, it should be cleaned prior to recording, preferably using a camera cleaning blower, so as to avoid scratching the surface and spreading the smudges on the substrate side.

Use a CD cleaning kit when cleaning is necessary. Carefully read the manual, before you start cleaning. Wipe the surface radially, in the direction from the center of the disc to the outer rim. Never wipe concentrically, along the mark tracks, since such wiping may drastically damage the function to record the digital signals in sequence due to the concentric scratching. Avoid using the cleaner liquid for record discs (conventional mechanical ones) or other cleaning agents. Use only CD cleaning liquids.
Take care not to spatter your saliva onto the CD-R disc when "breathing on them", when a camera cleaning blower is not available.

Avoid Bending and Dew Condensation
When the site temperature and humidity change abruptly, the equilibrium between the atmospheric humidity and the humidity inside plastic substrates of CD-R (and of CD as well) is broken, sometimes causing a slight bending of the discs and a little dew condensation on the surface. If this occurs, leave the discs near the writer for a while before using them so that they can reach equilibrium in the new environment.
Take Precautions After Recording ( not only Before Recording )
Avoid Scratching on the Label Side
As described earlier, the recording layer lies only about 5μm deep from the surface of the disc, which makes the recording layer vulnerable to scratches on the label side. Any scratches on the protective layer(:label side surface) may cause detachment of the protective and reflective layers, resulting in malfunction, this is because the recording layer is sandwiched between the reflective layer and the substrate. When writing letters on the label side, an oil-based felt-tipped pen should be used. Do not use a ball-point pen or other writing instruments with a hard tip. For safety, instant letterings or titles, already written, should not be erased.
Do not Attach Seals to the Label Side
Do not attach seals to the disc, which may cause, not only eccentric rotation, or crooked rotation in a disc changer unit, but may also have a harmful influence on the recording layer.
Do not Detach Already Existing Seals or Labels
Do not detach existing seals. Such an action could adversely affect the protective and/or reflective layers, since they may suffer detachment in the worst case, resulting in loss of the data.