Not exactly; the specification called for a plastic layer on both sides of the metal data layer. In cheaply produced media however the top layer (top here = the

Not exactly; the specification called for a plastic layer on both sides of the metal data layer. In cheaply produced media however the top layer (top here = the one with the print on it) was made as thin as possible, or even omitted and just coated with a printing. Also, there were cases where the two layers were joined/glued together inadequately, not properly sealing the metal layer from the environment. All of this led to the oxidation of the metal layer; rendering it unusable.