The 3 x 3" #70 Dark Red Wratten 2 Gel Filter from Kodak is designed to separate tones and build extreme high contrast in black and white photographs.
The filter absorbs blues and greens and enhances reds, which is ideal for infrared photography, which blocks visible light up to 650nm. Therefore, skies become more dramatic and the infrared effect becomes much greater. The Dark Red filter is also used for color separation; therefore, combining with other primary colors to create a color image.
Kodak has made improvements over the previous line of filters, and the Wratten 2 filters contain the following improvements: The gelatin is more ridged and durable, colors are more resistant to fading and degradation. Fingerprints and smudges wipe easier off the gelatin. The filters are also less sensitive to humidity, and the filters create less static cling. Therefore, are less prone to sticking to other filters or materials.
Creates extreme high contrast and separation of tones