I recently did a project to digitize a couple of Voice-O-Graph records dating back to the 1950’s. Voice-O-Graph made recording booths where you could make your own recordings on 78 or 45 RPM disks. These disks were 78 RPM and showed a bit of cracking and warping.
When confronted with poor condition like this, it is best to do as little as possible to the record. While you want to get the recording off the record, you need to prevent inflicting further damage. I don’t want to use any glues or coatings. I’d like to get the record into a flat plane so the stylus can ride in the groove, and that’s all. The cracks will certainly cause some pops, but that can be cleaned up later, in the digital editing.
In the end, both recordings had minimal popping from the cracks. My customer had requested minimal cleanup, so I trimmed the EQ to cut down the rumble and hiss and to accentuate the recorded voices.