Phonograph Records Light cardboard or heavy paper discs were coated with varnish into which a spiral groove was cut by the inexpensive home, amusement park and servicemen's club recorders of the late 1930s and 1940s. They were better suited to speech than music. These are the most time intensive old recordings to restore. They were cheaply made, usually poorly recorded and prone to considerable damage in storage and when being replayed.
Surfaces craze, bend and tear and stick together.
There are loud bangs that have to be taken out and the background crackle reduced. Even so, unaccustomed listeners may not be happy with the unremovable surface noise. Yes, it can come out, but the distinctive quality of once-familiar voices is usually destroyed in the attempt. Charges to restore the larger ones are proportional.