Just put one teaspoon of vinegar in a cup of hot water and mix it. Soak the cloth in the mixture and wring it thoroughly. You don't want wet cloth to clean your pickups with it. The cloth has to be just dampen enough.
How do I get rust off my guitar?
The easiest way to remove rust from your guitar parts is to simply soak them in white vinegar. Use a container that is big enough for the parts you need to soak and submerge them in white vinegar for three to four hours. Remove each part from the white vinegar bath and gently scrub off the rust with a shop cloth.
How do you clean guitar pickups?
Most guitar pickups can be cleaned by wiping them thoroughly with a clean cloth dampened with a touch of soapy water (damp, not wet!) or a bit of non-abrasive household cleaner such as 409. Use an old toothbrush to scrub between the posts and give the spots that have a build up of grime a little extra elbow grease.