sentence: AZO dye is usually dark blue or blue-ish silver.
sentences_before: There are three types of dye used in CD-R discs. The most common is phthalocyanine, and it is usually light green. It is usually teal or dark green. Verbatim uses phthalocyanine dye on some discs, and AZO dye on others.
sentences_after: The metal layer on the disc is usually made of silver. Archival discs and some professional audio discs use a gold top layer.
concept_name: azo dye
headings: CD-R
categories: Compact Disc