Warm colors - any colors which, by association, suggest warmth, such as red, orange and yellow.
Washing - the final part of the processing cycle, which removes residual chemicals and soluble silver complexes from the emulsion.
Water bath - large water filled containers used to maintain processing trays, tanks or chemicals at the correct temperature.
Water softeners - used to eliminate most of the minerals and slats found in hard water.
Watkins factor - an old system of development control, based on observation of the processing image under safe lights.
Watt - a unit of power in electricity.
Watt-second - an alternative unit of energy, equal to the joule.
Wavelength - the distance from wave-crest to wave-crest between two corresponding waves of light in the electro-magnetic spectrum. Wavelengths are measured in nanometers (nm) and Angstrom units (A).
Waxed paper process - an early form of photography. A variation on the calotype process.
Weak - a negative or print which is low in contrast or density.
Wedge spectrogram - an indication of the spectral sensitivity of a sensitized material by exposing it to a spectrum of light through a graduated gray wedge.
Wet collodion - a much improved calotype developed by Frederick Scott Archer. A sensitized glass plate was dipped into a bath of silver nitrate and exposed while still wet. The improved speed made much shorter exposures possible.
Wet processing - processing by the application of chemicals in fluid form. The traditional method of photographic processing.
Wetting agents - chemicals which, when used in minute quantities, reduce the surface tension of water. They are usually added to the final wash of films and plates to improve draining.
White light spectrum - the electromagnetic wavelengths between 400-700 nanometers. Also referred to as the visible spectrum.
Whole plate - a negative or print format measuring 6 * x 8 * inches.
Wide-angle lens - a lens with wide covering power. It has a focal length which is less than the diagonal of the film format with which it is being used.
Wood grain - a term for a pattern formed on a hologram by polarized.
Wood print - a print made on a wood surface which has been photochemically prepared.
Working aperture - the widest aperture at which an acceptable image can be achieved.
Working solution - a liquid chemical that has been mixed and diluted for use.