“The demand for [banned] pop and jazz recordings at the end of the fifties and beginning of the sixties [in the USSR] was enormous. This led to the birth of a legendary phenomenon — the memorable records ‘on ribs.’
These were actual X-ray plates … rounded at the edges with scissors, with a small hole in the centre and grooves that were barely visible on the surface. Such an extravagant choice of raw material for these ‘flexidiscs’ is easily explained: X-ray plates were the cheapest and most readily available source of necessary plastic. People bought them by the hundreds from hospitals and clinics for kopeks, after which grooves were cut with the help of special machines (made, they say, from old phonographs by skilled conspiratorial hands).”
Artemy Troitsky, Back in the USSR: The True Story of Rock in Russia (1987)
Quoted in a fascinating article about the roentgenizdat or x-ray press, the audio counterpart of Soviet underground literature’s samizdat. Apart from the political context, they’re also strangely beautiful as objects, niet?
PS: Check out the article’s comments section, too.