Because of the potential hazards caused by flame effects, concert promoters often have to observe fire codes and obtain a license from the fire department in the city in which the concert is performed. Flame effects can be shot from flame cannons or flame bars. With flame cannons, fireballs can be launched as high as 35 feet in the air. In contrast, flame bars are able to launch fire in the form of shapes. Some concert entertainers also use colored flames to match set or costume designs or for additional entertainment value. Flame effects use raw fuel such as gas or propane and depend upon natural air to burn.
Fog effects are a form of cyrogenics used during concerts. These effects come in the form of low-smoke fog generators, fog curtains, fog walls, fog curtains and fog screens. Fog generators are designed to produce fog through pumps that are inaudible. Thus, the machines can be used for longer durations during shows without added noise. Fog curtains and fog walls are more complicated effects because of the need for projectors and are best used for indoor concerts. Outdoor wind can adversely affect fog curtains, in particular. Finally, fog screens operate as projectors and use dry fog to produce images that float in the air. For larger concerts, several fog screens are linked together to create images that fill the stage and concert space.
The goal of laser lighting is to remove the feeling of being a spectator in favor of being a part of the concert. Whether using laser beams or laser scans, entertainers use these effects to heighten the audience's attention. Two types of laser lighting devicesare often used, the Copper Vapor Laser and the Baby Yag Laser. The Copper Vapor Laser is used to provide color variation--in addition to green lighting--with an emphasis on gold and teal colors. The Baby Yag Laser offers its standard green color and is designed for smaller concerts and is less cumbersome. Laser lighting also can be synchronized with music or projected on to a screen.