I suppose you could put a coat of wood protecter on it and it would help. The best thing though is to get a ping pong table cover.
Ping Pong (table tennis) tables are mostly made of wood and wood will warp. Normally because of two reasons; one is moisture and the other is the frame it's attached to is not strong enough to support it, or both.
Ping pong tables are generally made of masonite or a similar type of hard wood, and then covered with a coating that gives a nonfriction surface.
There is no one type as there are many types of wood used in table tennis rackets. The type of wood and the layup of that wood, often mixed with carbon fiber, depends on the playing style and dwell time desired. That said, the favorite type of wood used by Japanese-penholder style of play is called Hinoki.
Since most table tennis tables are made of a wood composite, just a damp cloth will do. Then use a dry one to dry it because you do not want to leave it wet.
it is made of wood cover with rubber to make the ball spin
A paddle of any size and weight can be used in ping pong but it must be 40% wood and it must have red rubber on one size and a black rubber on the other.
According to http://www.sizes.com/sports/table_tennis.htm, a table tennis racket may be of any size, shape, or weight. 85% of the thickness must be natural wood.
Not to be obscure, but what kind of table do you mean? A commercial, aluminum folding table is reasonably light, while a homebuilt table with an inch-thick composite wood top and 2x4 legs and braces takes two men and several children to move.
Most are made of wood, but a few (more expensive ones) are made of metal, primarily aluminum.
The Official Laws of Table Tennis state that a table tennis racket (ping pong paddle) can be of any size, shape or weight. The rules also state that the blade must be flat and rigid with at least 85% of it (by thickness) made of natural wood. Most rackets are actually all very similar in size - about 15cm (6 inches) across and 25cm (10 inches) long, including the handle.