an overview of masks: what they are; what they do. Masking is selective dodging.. consider it a precise, custom, graduated neutral density filter. Masks are most often used this century to alter contrast of B&W film. They also increase local contrasts, thereby altering edge effects making a print appear sharper with more gradations. These are the “unsharp masks (USM)”

In last century, during the growth stage of masking, they were used in color processes to alter, and correct contrast and color. Masking increased the contrast of the magenta and yellow, overcoming deficiencies, impurities of colorants.

Films I have today for masking: Ilford PanF (120). Ilford Delta 100 (4×5 & 8×10). Ilford Ortho+ (4×5, 8×10, special roll). Note the Ilford weight. I do, and it makes me nervous, since Ilford hangs on the interest of real estate ventures in a country of short term values.

From the past; more for the Rosetta stone. Translating data sheets. Why that film/developer was made.

Masks should never be greater than 40%. Coated (APO) lenses require higher percent masks.

The appearance of color swatches in separation negatives is best indicator of correct mask exposure.

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Developer for masks, like those for seps should be non-staining and not “fine-grain” solvent type. It is easy to recommend DK-50, DK-60a as best options, even this decade. For ready mix, try HC-110 one-shot. All masks and seps should be processed following a one-shot protocol. Use the mixture one time and discard. I use fresh developer for each sheet of film.

Filter	Use
F- 29 Red	Required
N- 61 Green	Required
#96 Neutral density: 0.10 / 0.30 / 1.0	Strongly recommended. Equalize exposures. Reduce reciprocity differences.
#33 Magenta	optional
#15 Yellow	optional