I don't remember ever boiling strings back in the 60 or 70s. Other people talked about doing it but it seemed too much like hard work to me. What I did do was wipe them with a small piece of cloth soaked in methylated spirit or white spirit. I didn't unwind them or de-tune them, just soaked the rag in the solvent, wrapped the rag around one string at a time and ran it up and down the string a few times. It made a terrible squeaking sound on the unwound strings.