The 3 x 3" #21 Orange Wratten 2 Optical Gel Filter from Kodak is a bright orange filter that darkens blue, violet, green and yellow-green. It is particularly useful for all landscape and architectural photography (on black and white film) requiring vivid contours. The sky is distinctly toned with the clouds clearly contrasted against it. It is suitable for landscapes and nature scenes.
Wratten 2 Improvements
Easier to handle
Color consistent today, and 6 months from now as well
Wratten 2 Optical Filters are less sensitive to humidity, less prone to static cling
Most Kodak gelatin filters are available in 3 x 3" (75 x 75mm), 4 x 4" (100 x 100mm), 6 x 6" (150 x 150mm), and 14 x 18" (350 x 450mm).