Slag is one of the four materials used in the construction of tennis fields, besides polyurethane, artificial grass and painted cement. Slag can be made of stone or brick. Red slag provides a faster play surface, compared to the green one or the American slag “Hartru”. The French open uses slag fields, making them unique through the Grand Slam tour. Slag tennis fields are more common in Europe and Latin America, as compared to the USA, Canada or Great Britain. 


Slag fields imply lower costs for the construction itself but they are more difficult to maintain than other types. Clay is more expensive to maintain in order to keep a smooth, flat play surface. Playing on a slag field often presents the risk of sliding.

One of the advantages offered by the slag tennis fields is the fact that the game is safer, the traces left by the ball are visible, making possible to determine whether the ball stayed in the field or it went outside. Slag tennis fields are more defensive and they helped players such as Nadal or Henin to be successful at the French open.