It's a simple concept – keep your inverted sponge rubber clean!!! It doesn't take much play for the surface to gather dust and lose some of its grippiness. It may not seem like much since it's a gradual process, but it really can make a difference – though often players don't notice it. (Related to this is that you should get new sponge periodically – the surface wears down and the sponge gradually loses its bounciness. Since I play 6-7 days/week, I change both sides every month; others who don't play as much may go six months or even a year, though the latter is a bit long if you want to have lively, spinny shots.) Here's my three-part recommendaton:
- Wash it off with water before every session. The simplest way is to wet a corner of a towel (and you do have a towel when you play to wipe away sweat and clean your racket, right?), and wipe it off with that. Then wipe the water away and dry the racket with a dry part of the towel.
- A few times each game simply breathe on the sponge's surface, and then wipe it on your pants or towel. This gets rid of gathering dust.
- At the start of serious competitions, and perhaps once a week otherwise, use rubber cleaner to really clean it off.