Definition: Booster is a liquid applied to sponge rubber to achieve a speed glue effect, or to temporarily reactivate the speed glue effect after the effect has worn off.
Since repeated speed gluing of a rubber can make the rubber significantly heavier due to the build up of glue in the sponge, and reduce the speed glue effect, booster can be handy to regain the speed glue effect without causing further build up of speed glue in the sponge.
While boosting by players is illegal under ITTF rules, modern boosters are difficult to detect, and it is generally acknowledged that most professional players boost their rubbers.
