In the olden days

I used to soak a rag in white spirit and wipe the cables clean. This would have a dual purpose of hopefully snagging any broken strands on the rag rather tearing into your hand, as well as cleaning. I would also note where the cable passes through any pulleys and/or fairleads and bend the cable to see if any strands stick out. Once the cable is nice and clean and pleasing to the eye, we would then soak it in Boeshield, either in a trough we had in the cable shop or a plastic bag if out in the field. The cable assembly would be rolled up and the excess Boeshield allowed to drain before fitting to the areoplane. Boeshield is good stuff, in that it will penetrate into the core of the cable, but dries off externally to a waxy finish to protect the cable.