Invisible spray for World Cup finals

Sepp Blatter, FIFA President, has announced that a vanishing spray will be used at free-kicks to mark a line on the ground where the defensive wall and ball must be placed.
The water-based product, which disappears about a minute after use, was successfully used during the Club World Cup in Marrakesh recently.
The spray, developed by Brazilian Pablo Silva, has previously been used in matches in South America and Major League Soccer in America.
Fans have become increasingly incensed when players encroach at a free-kick. The spray will be used to stop players in the defensive wall creeping closer to the ball, while a circle is also drawn where the ball is to be placed for a free-kick.
Some supporters would welcome the introduction of a vanishing spray for officials!
C.W.