Thomas Color Safelight Filter Set (FCD) are remove-able vane filters for use with the Thomas Duplex Super Safelight, when processing RA-4 Color paper.
Proper placement of move-able vanes and filters (in body and vanes) is imperative to create the most safe darkroom conditions. Please see PDF instructions.
For color papers, the vanes should be fully closed with the yellow-edged filters (FBD) in the body and the black-edged filters (FCD) in the vanes, so that light passes through both sets of filters. The light will be extremely dim.
Note: Always test your material with the safelights at varying levels of illumination and distance, to insure the safelight is safe when installed.