Rosco Supergel is the most widely used colour filter in the world today. It is comprised of a range of more than 75 colours and 15 diffusions. Selected primarily because of the excellence and range of colour, it is unique in its manufacturing and durability as well.
3 mils Typical (3-5 mils in extremely dark colours)
Melting Point 220°C
Softening Point 160°C
The softening point is where the filter begins to show stress marks and break down. We prefer to use polycarbonate plastic because of its higher softening point.
The life of colour filters depends on many variables: the colour, the instrument and lamp used, the dimmer level a filter generally runs at, and the amount of time the light is running. For these reasons it is impossible to assign a “life” for each filter. However some basics knowledge and experience can help with estimates. Dark green and dark blue filters usually burn out the fastest because they absorb the most infrared energy. Absorbing the extra infrared energy causes the plastic to reach it’s melting temperature faster. When darker filters are needed try choosing filters that transmit high amounts of the 700 nm range. You can find this information by looking at the Spectral Energy Distribution (S.E.D.) curve located in the swatchbook for each Supergel colour filter. Filters than transmit high levels at 700 nm may also transmit high levels in the infrared range above 700 nm.(See the Supergel swatchbook for information on how to read S.E.D. curves.)
To prolong the life of a colour filter, align your ellipsoidal lamp to a flat field focus. (Get rid of the hot spot.) You can increase the distance between the lamp and the filter by using a top hat or barn door. In extreme cases, try Rosco Heat Shield or Thermashield to prolong the life of your filters.
Never use a plastic filter directly in front of an open faced lamp. This will nearly always cause premature failure because the heat is trapped and it has nowhere to go except to the plastic filter. Always allow a suitable air gap