The use of spray paint by referees is increasing in more countries.
This product is currently reducing the problems that occur amid contentious player positioning before many free kicks.
The spray makes a white line on the grass or artificial surface which will clearly show encroachment by players attempting to narrow the angle or affect the taking of the kick. Its use is becoming more common because it is providing good results.
Vanishing Spray available in US !!
As a result on March 3, 2012 the IFAB granted its approval and also permitted soccer associations around the world to use vanishing spray to help ward against players encroaching too far forward when defending free-kicks.
Before making any markings, the referee must always shake the can to obtain a clean spray stream and then press the valve tab with the spray tip pointing down toward the field. The height to spray from may vary between 8 inches (20 cm) and 16 inches (40 cm). The distance from the field surface will affect the width of the resulting line. From 8 inches the line will be about 3 inches wide. This may be different from product to product.
A spray made from a height of 16 inches will make a line about 6 inches wide. In rainy or windy conditions, it is more effective to spray more slowly from a lower height (6 inches). This way, a more consistent line is made in spite of the conditions. In good weather it is not even necessary to look at the field when spraying. The referee may well see the markings as helpful without interfering with other field lines.
It is recommended that a line marking the position of a defensive wall not exceed about six feet (two meters) in length. By making two long steps the referee can estimate the required distance. The position of the ball is marked by a circle. Each spray can contains enough paint to make seven wall lines and ball circles. When the referee has made six markings it is time to replace the can. It is recommended that referees do this at half time even if it has been used only once, so as to have the benefit of a full can.
Where you can get it:
Finally we can get a vanishing spray here in US.
The company "RefEdge" with base in Cumberland, Maine design a spray paint that in my opinion works really good. You can buy it from them in a case (6 botlles per case) for $59.49 plus tax and shipping. You can also buy the holster which one of the best so far.
As a personal note, I try this product and it works really well and it's a great tool! - Francisco.