stains

Just 2 days ago i bought a DHS Skyline 3 3-60. After the 2nd session, i noticed some stains on the rubber, i tried to wipe them out with some water on a kitchen sponge but nothing happened. Can you guys give me some advice?

I've recently returned to the fabulous sport of table tennis after an absence of 25 years and (like everyone else?) I'm a bit puzzled with the new plastic balls. I'm getting used to the slowness but I'm failing to understand the white powder that all balls seem to be covered with (so far I've...