I’m debating the value of adding a reflective layer to the back. Based on the way pressed CDs are read (depending on the constructive interference of the light because the pits are about 1/4 wavelength deep) I would argue the reflective layer needs to be on the lands and within the pits.
And if a reflective layer is damaged, does it peel away from the pits without damaging them? Does the acrylic lacquer adhere to the aluminum so well they peel off together without harming the pits? Certainly some forms of damage would harm the pits.
I guess another hypothesis would be that today’s readers need to see a certain amount of light coming back or they’ll conclude there’s nothing there. Perhaps once it gets some light, it’ll try to interpret the signal enough to read the 1s and 0s.
On a junk CD and one of those blanks from a CD cake box, I sprayed some Krylon “Looking Glass” paint. On glass, it makes a mirror finish. On the polycarbonate, it was gray… Come to think of it, quite like thermal paste. I couldn’t quite tell if the solvents in the spray paint were crazing the plastic or the painted label.