If you look at the layers, the shiny side (bottom) of a CD is a thick layer of plastic. The data is actually on the other side of that plastic, protected by a thin sheet of aluminum foil and lacquer on top. Even a deep scratch on the bottom is unlikely to reach the data, so resurfacing should be very effective.
However, a deep scratch on the top can easily puncture the metallic layer and damage the actual data.
DVDs and Blu-ray have extra layers and are a bit more complicated, but it’s a similar design
sbexpert@lemmy.world 5 months ago
I learned that data was on the top side at a very young age. I put a sticker on top of a CD and a couple years later peeled it off and the image came off too. I tried to play the CD and realized my mistake. I think I was around 7. Luckily it was just kid’s Christmas songs and nothing important lol.