Black and White Signature Series gobos ("lithos") have been made using an ultra-thin aluminum coating, etched with super fine details to create incredibly smooth gradients patterns.
Spectrumgobos can withstand temperatures found in modern ellipsoidal luminaires ("lekos") that use the new generation of sub-1000 watt lamps and a dichroic reflector. Moving lights using metal halide sources up to 1200 watts are generally compatible as well.
However since some luminaires generate an abnormal amount of heat, it is advised to check with Rosco to see if your fixture is suitable for use with Spectrumgobos.
Note on Aluminum Coatings:
Aluminum is often used as a coating on glass due to its extreme resistance to heat. Such typical aluminum coatings suffer from two significant flaws. First, aluminum is generally soft and scratches easily. Also, the highly reflective nature of aluminum may create imaging problems when a secondary reflection off the lens is reflected back into the optical path by the aluminum coating on the gobo.
Both of these issues may create significant gobo problems.
Rosco Black and White Spectrumgobos utilize an "Ultra-Matte" aluminum coating. Using a unique manufacturing process, the aluminum is hardened to resist scratching and then the surface is burnished to a matte finish to reduce the possibility of double reflections. And unlike other gobo manufacturers who have turned to a "blackened" coating which fails dramatically if installed improperly, the Rosco Ultra Matte coating can be installed with either surface towards the lamp.