Trying to determine whether a gobo is suitable to be used in a specific luminaire is not simply a matter of determining the proper size of the gobo. Today's glass gobos are heat sensitive and there may be situations where a glass gobo cannot be used in a specific luminaire due to excessive heat. While the heat generated inside a luminaire is determined by many factors, we can use lamp wattage as a reasonable estimate.

The following table indicates suggested maximum wattages for each type of Rosco gobo. Certain fixtures may generate more or less heat at a particular wattage. We have indicated those exceptions about which we are aware.

A determination that a particular gobo is not suited to a fixture due to extreme wattage assumes long term usage of the gobo/luminaire combination. Using a gobo in a luminaire with excessive wattage for just a short period of time may prove to be perfectly acceptable.

Remember - these are just guidelines. Your results may vary!


Gobo Type Wattage Limits
Silk Screen Gobos
Profile: 2500w
Automated: 2500w
Notes:
Glass substrate rated to 1100° C. Gobo guaranteed for 1 year in luminaires up to 1000w.
Colorizers™
Profile: 1200w
Automated: 1200w
Notes:
Glass substrate rated to 450° C. Ceramic coating rated to 600° C.
Image Glass™
Prismatics™
ColorWaves™
Profile: 600w
Automated: 1200w
Notes:
(a) HPL-750 in Source Four may be used for short term applications. Over exposure causes gobos to crack. Cracked gobos are still usable since these style designs are typically used in soft focus.
(b) GLA-1000w in Selecon Pacific appears to be acceptable for all three gobo types.
(c) ImageGlass and ColorWaves may be tempered to increase heat stability. Contact Rosco for information about additional cost and delivery time.
(d) Prismatics may degrade after long term exposure to maximum temperature limits. Chips may separate from glass base at this stage.
Black and White Spectrumgobos™
Profile: 750w
Automated: 1200w
Notes:
(a) Rosco uses a matte aluminum coating in producing Black and White Spectrumgobos. This matte coating is designed to help reduce double reflection problems in luminaires with very high quality optical systems. In order to achieve this, install the matte side of the gobo away from the lamp. Unlike other low-reflection aluminum coatings ("black" aluminum) improperly installing Rosco's gobo will not cause the gobo to fail.
(b) Older gobos using Chrome coating instead of aluminum would burn and fail in high wattage profiles. While the matte aluminum Rosco uses is more durable, the glass itself is still very sensitive to hot-spotting. For maximum life span from your gobos, make sure that your luminaire has been properly bench focused to a flat field.
(c) When using Spectrumgobos with the Vari*Lite VL1000, make sure your VL1000 has been modified with the heat reducing kit provided by Vari*Lite (fan bypass circuit adjustment and "cowboy hat" installed).
One Color Spectrumgobos
Profile: 750w
Automated: 1200w
Notes:
(a) For best results, install dichroic gobos with the coating side towards the lamp. To determine which is the coated side, use this easy optical trick. Holding the gobo at an angle, touch the tip of a pencil or similar pointed object to the surface of the gobo. If the pencil appears to touch its reflection on the surface of the gobo, it is touching the coated side. If the reflection and the pencil remain separated slightly, that is the uncoated side.
(b) When using Spectrumgobos with the Vari*Lite VL1000, make sure your VL1000 has been modified with the heat reducing kit provided by Vari*Lite (fan bypass circuit adjustment and "cowboy hat" installed).
Two Color &
Multi-Color Spectrumgobos
Profile: 750w
Automated: 1200w
Notes:
(a) When using Spectrumgobos with the Vari*Lite VL1000, make sure your VL1000 has been modified with the heat reducing kit provided by Vari*Lite (fan bypass circuit adjustment and "cowboy hat" installed).
Hi-Definition Photogobos
Profile: 750w
Automated: 1200w
Notes:
(a) The Clay Paky Stage Zoom 1200 has a particularly tight focused optical path that is excessively hot. Clay Paky has introduced a kit to reduce the heat on the gobo. Be sure to use this kit when to reduce the heat on Hi-Def Photogobos or premature failure may occur.
(b) When using Spectrumgobos with the Vari*Lite VL1000, make sure your VL1000 has been modified with the heat reducing kit provided by Vari*Lite (fan bypass circuit adjustment and "cowboy hat" installed).