A Class 4 laser beam can cause materials to smolder or burn, especially at close range. Keep the beam moving to avoid burning materials at close range. Dark materials which absorb heat, and lightweight materials such as paper and fabric, are most easily burned by visible laser beams. Laser glasses or goggles should be used when working with Class IV lasers, especially at close range (within a few yards or meters). They should be selected to protect against the laser's power and wavelength. The eyewear should not block out all of the laser's light. This is because it is necessary to see where the laser "dot" is, to safely work with the laser. Because the eyewear is blocking some or perhaps all of the laser's light (for example, a hazardous reflection) you still should use caution even when using laser protective eyewear. As you are using the laser, any other persons in the area should also have the same type of laser protective eyewear as you.