How does the NHL put the red and blue lines under the ice on a hockey rink?

The ice in a hockey rink ranges in thickness from 3 inches to a mere 5/8 inch in places such as Madison Square Garden, where ice must be made and taken up in a matter of hours.

This thin ice is a trial to professional players who make abrupt turns or screeching stops and sometimes scrape the floor below with their blades.

Depending on the time factor and the thickness of the ice, a variety of methods may be used to get those mysterious blue and red lines, circles, and insignias under the ice, and to erase them again when necessary.

If all the ice is removed from the rink, a water base paint may be applied to the concrete floor that lies below. The entire floor is painted white with 6 foot wide squeegees pushed by hand; then the lines and circles are painted on with the help of wood stencils.

A second method, which is a bit trickier but more common, involves building up a thin layer of ice about 1/4 inch thick. After the entire surface of the ice is painted, a machine called a Thompson edger is used to cut shallow grooves Vs inch deep into the ice, thereby marking the placement of the lines.

Red or blue paint is applied by hand with brushes or simply poured into the grooves, which prevent it from running. As soon as the paint dries, a layer of clear water is spread over the ice to provide a coating. When in a few hours this coating has frozen, more ice may be built up to the usual level of 2 or 3 inches.

This process, which may take two days, is obviously impractical in a stadium where a horse show is scheduled for Friday night, a National Hockey League game on Saturday. A method used with increasing frequency these days substitutes plastic or paper for paint. The material is simply spread right onto the floor, and ice is then made over it.

After the game both the ice and the lines may be taken up to make way for the next event.