Rosco 104

Overview

Rosco #104 "Tough Silk" is a diffusion filter from the Roscolux or Cinegel series by manufacturer Rosco. It is not a color filter, but a so-called "Silk" diffusion: the filter has a directional structure that preferentially stretches light along one axis, while the diffusion across it remains significantly lower. This creates an elongated beam of light ("slash of light") that nevertheless retains a relatively compact beam shape.

Important Distinction: The number 104 is used twice depending on the Rosco filter system. In the Roscolux/Cinegel series (American numbering system), #104 stands for "Tough Silk" (diffusion). In the European E-Colour+ system, however, #104 denotes "Deep Amber" – a strong color filter (equivalent to Lee #104, as E-Colour+ and Lee use the same European numbering system). Therefore, when ordering and stocking on set, the product series must always be specified.

Function and Effect

The directional Silk structure of #104 runs as parallel lines through the material. Depending on how the filter is rotated relative to the light source (horizontal, vertical, or diagonal), the beam of light is stretched along this axis:

• Stretches and distributes light in a preferred direction, rather than scattering it all around.
• Suitable for drawing light across elongated surfaces – such as stairs, tables, or backdrops (cycs).
• Retains more beam compactness compared to non-directional diffusers.

#104 is considered a medium-strength diffuser within the Tough Silk family. Weaker variants (e.g., "Light Tough Silk") produce a comparable effect with less light loss.

Material and Construction

Roscolux filters are manufactured as body-colored, with the color or structural carrier embedded in the polyester or polycarbonate substrate, rather than being a surface coating. This improves color and structural stability, as well as resistance to fading. The series is designed for use in front of hot theater, film, and TV lights; high-temperature substrates have correspondingly high softening and melting points.

On-Set Use

Tough Silk is placed in front of a lighting fixture or in filter frames / gel frames. Typical applications include the directional stretching of a light strip, the soft application of light to elongated subjects, and the smoothing of hard edges without completely dissolving the beam. #104 is available as a sheet (e.g., 20" × 24") and as a roll (e.g., 24" × 25 ft).