Thomas Black And White Safelight Filter Set (FBD) are the yellow-edged filters for use in the body of the Thomas Duplex Super Safelight. They are required for proper use of the safelight, regardless of material type.
Proper placement of moveable vanes and use of the proper filters is imperative to create the most safe darkroom conditions. Please see PDF instructions.
For all black and white printing papers, the vanes should be open with the yellow-edged filters (FBD) in the body and the red-edged ones (FOD) in the vanes. At the maximum opening, the safelight should produce perfect illumination for darkrooms approximately 12 ft x 14 ft with a standard 8 ft ceiling height. Smaller darkrooms may require reduced level of illumination, which is achieved by lowering the vanes. If your material instructs you to use RED light, as oppose to AMBER (OC), close the vanes completely.
Note: Always test your material with the safelights at varying levels of illumination and distance, to insure the safelight is safe when installed.