Tue Dec 03, 2013 7:35 pm by mleipold
Regarding the copper RF coil:
1. There is a distinction between soot (powder that can be removed with a Kimwipe and methanol), and simple oxidation of the copper in the coil.
When a coil is new, it is the regular copper color. Over time, it will turn greyish or at least darker. This color change is to be expected: it's an oxidation of the copper (or, maybe an argon adduct; I don't know the chemistry behind the color change). This color change is harmless, and will not affect the running of the machine. Therefore, it doesn't need to get removed.
Soot, on the other hand, should be wiped away with methanol on a Kimwipe (please use Kimwipes, or some other certified lint-free material). I *think* this soot is copper in origin, but I'm not sure. Regardless, you do want to remove it, or it can contribute to arcing events. But wiping with a methanol-wetted Kimwipe usually is sufficient to clean. Balling it up lightly so it can wedge into the coil turns usually works well enough.
To get between the coil turns, or between the torch body and the coil, you can cut a section of pipe cleaner (craft supply stores have them as well), dip in methanol, and run in the areas needed. You can also use a pipe cleaner for cleaning the injector tip, and the narrow end of the spray chamber near the ball joint (where a lot of scrub brushes have a hard time reaching). I would watch out for lint, and also use the white pipe cleaners (the dyes in colored products are sometimes metal-based).
2. In most cases, a kitchen scrub pad is usually sufficient to scrub the coil and igniter pin to remove oxidation (in the US, they're often green; don't get the kind with embedded detergent). Fine-grade andpaper is usually only required if there is significant damage to the Rf coil after an arcing event. Scrub at the spot lightly until it's smoothed again, then with the green scrubby, then wipe with methanol until no soot comes off onto the Kimwipe or pipe cleaner.
In all cases, cut down the size of the scrubby, sand paper, or pipe cleaner so it's easier to reach into the machine (CyTOFv2 is a little easier in that regard than CyTOFv1).