Variable Contrast Paper and Multigrade Filters Explained

Variable contrast paper lets you change a print's contrast with filters instead of buying paper in separate grades. One box can print a flat negative and a contrasty one equally well. Learning how the filters work, and how to split them, gives you more control over a print than almost any other darkroom technique.

How it works

Variable contrast paper carries two emulsions mixed together: a high-contrast one sensitive to blue light and a low-contrast one sensitive to green light. Changing the color of the enlarger light changes the balance between them. Yellow filtering removes blue and gives soft, low contrast; magenta filtering removes green and gives hard, high contrast.

Filter grades

Filter sets, often sold as Multigrade filters after Ilford's paper, run from grade 00 to 5 in half-grade steps.

Grade	Contrast	Use for
00 to 1	Very soft to soft	Contrasty negatives, harsh light, overdeveloped film
2 to 2.5	Normal	A well exposed, normally developed negative
3 to 3.5	Slightly hard	Slightly flat negatives, overcast scenes
4 to 5	Hard to very hard	Very flat or underdeveloped negatives, graphic effects

With no filter at all, most variable contrast papers print at around grade 2. Filters can go above or below the lens, or you can dial in yellow and magenta on a color enlarger head using the paper maker's conversion table.

With many filter sets, grades 00 to 3.5 need about the same exposure, and grades 4 to 5 need about double. Check the instructions for your filters.

Choosing a grade

Make a test strip at grade 2 and choose the time that renders the important highlights correctly. Then look at the shadows. If they are gray and weak, go harder; if they are blocked and black with no detail, go softer. Adjusting grade mainly moves the shadows once highlight exposure is set.

Split-grade printing

Split-grade printing exposes each print twice: once through the softest filter (00) and once through the hardest (5). The soft exposure mainly controls the highlights; the hard exposure mainly controls the shadows. Changing the ratio of the two times gives every intermediate contrast, and you can dodge or burn each exposure separately, for example adding grade 5 to deepen a shadow without darkening a sky.

Make a test strip with the 00 filter and pick the time where the highlights are right.
Expose a second test strip with that 00 time across the whole strip, then add steps of grade 5 exposure.
Pick the grade 5 time where the blacks are rich and shadows still separate.

Graded paper

Graded papers have a single fixed contrast, sold as grade 2, grade 3 and so on. They are less common now, but some printers prefer their tonality, and they can be used without filters. A negative developed for graded paper should be matched closely, which is one reason the Zone System was so valuable before variable contrast paper.