The term coaster is often to used to describe an optical disk that was ruined
while trying to burn, or write to it (often caused by
buffer underruns). However, it's also used to refer to any
malfunctioning, unwanted or defective optical disk (CD
or DVD media). The phrase is one which really caught on, and today you can find
a plethora of CD and DVD burning guides which offer "coaster-free burning tips",
designed to help consumers create a working disk on the first try. Adding to the
terms popularity are Web sites that provide tips and tricks on
"decorating and customizing" your CD coasters.
Coaster-Free Burning with IDE CD Writers: Part 1 Anyone who uses a CD writer has made coasters, or ruined CD-R discs. CD burning is an isochronous, or time-dependent, process because the data to be written must be delivered to the CD writer continuously, from the time the write commences until it is finished.
Family Crafts - CD Coaster You can use any old CDs which have gone bad, but this looks best with plain gold or silver CDs.