Aluminium: Aluminium is used to make the reflective layer of a CD-ROM. It is a thin layer of metal that is applied to the substrate by vacuum deposition.
Dye: Dye is used to create the data layer of a CD-ROM. It is a light-sensitive material that is applied to the reflective layer by spin coating.
Protective coating: A protective coating is applied to the data layer of a CD-ROM to protect it from scratches and other damage. It is typically made of a material such as lacquer or epoxy.
Inkjet printable surface: Some CD-ROMs have an inkjet printable surface that allows you to print directly onto the disc. This is typically made of a material such as paper or plastic.