Editing CD-R (section)

===Data confidentiality===
Since CD-Rs, in general, cannot be logically erased to any degree, the disposal of CD-Rs presents a possible security issue if they contain sensitive/private data. Destroying the data requires physically destroying the disc or data layer. Heating the disc in a microwave oven for 10–15 seconds effectively destroys the data layer by causing arcing in the metal reflective layer, but this same arcing may cause damage or excessive wear to the microwave oven. Many office paper shredders are also designed to shred CDs.

Some recent burners (Plextor, LiteOn) support erase operations on -R media, by "overwriting" the stored data with strong laser power, although the erased area cannot be overwritten with new data.