For illustrative purposes:
I re-built that pack a year and half ago using solder wick. I used tape for extra insulation during soldering, to make sure the wraps wouldn't get damaged. It ended up being unnecessary. The flux, being liquid and pretty fluid, gets under the wraps and causes some superficial oxidation on the cells. Despite I cleaned them before rewrapping, some rust remnants can still be seen. If I were to dismantle the pack again, I'm pretty sure a nice bunch of additional rust pecks would be seen due to my second flux application to rebuild the pack. It is completely inconsequential, though.