Multigrade Filters in the Darkroom: Learning to Read Light in Two Passes

Variable contrast paper changed the way darkroom work gets done. Before it, you kept five or six boxes of graded paper on the shelf, one per contrast grade, and you juggled between them depending on the negative. Now a single box of Ilford Multigrade (or any equivalent) combined with a filter set covers the full range from grade 0 to grade 5. Convenient, sure. But you need to understand what you're actually doing with those filters, otherwise they stay magic dials you turn in the dark.

This is a working guide, not a chemistry primer. If you already know how to run a test strip and develop a print, you're in the right place.

What the filters actually do

Variable contrast paper has two emulsion layers, each sensitive to a different part of the spectrum. Multigrade filters control which layer does most of the work by shifting the color of the light reaching the paper.

Soft filters, around grades 0 and 1, are yellow-green: they pass green light and suppress blue, which drives mostly the low-contrast layer. Hard filters, grades 4 and 5, are magenta or violet: they block green and feed the high-contrast layer. In the middle, grades 2 and 3, both layers contribute in roughly balanced proportions.

Ilford Multigrade filter sets include 12 filters running from 00 to 5 in half-grade steps. Kodak Polymax filters are compatible with any variable contrast paper. Lee Polycontrast filters exist too, less common but perfectly usable. In practice, if you're printing on Ilford paper, Ilford filters are calibrated as a matched system and the consistency is built in.

Start with the crossed test strip

An ordinary test strip explores exposure at a fixed contrast. A crossed test explores contrast at a fixed exposure, or both variables at once. This is often where multigrade printing starts to make real sense.

The simple approach when you're starting out: run a test strip at grade 2, as you normally would, to find a reasonable working exposure. Grade 2 is where Ilford Multigrade is calibrated to a "standard" speed, so it's your reference point. Once you have a working exposure, say 10 seconds, make a short series of full small prints at that same exposure and just change the filter: one at grade 1, one at grade 2, one at grade 3, one at grade 4. Five minutes of work, and you can see how the negative behaves across the contrast range.

If the result is too harsh, drop to grade 1 and retest. If it looks gray and flat, go to grade 3 and retest. This sequence shows you quickly whether the highlights are blocking up before the shadows get any richness, or whether the shadows are filling in before the highlights have any substance. That imbalance is what usually pushes you toward split-grade printing.

Building exposure in two passes: split-grade printing

Split-grade printing means exposing the same sheet of paper twice: a first exposure at grade 0 for the highlights, a second at grade 5 for the shadows.

Why does it work? The soft exposure builds highlight detail, but leaves shadows thin and weak. The hard exposure then "burns" the shadows and gives them density and depth. The two emulsion layers are handled more or less separately.

Split-grade printing is often faster for establishing a working contrast than chasing a single-grade solution, especially with a difficult negative.

How to do it

1. Put a grade 0 filter in the enlarger.
2. Run a test strip across the full width of the image in 5-second steps. Develop it. Find the exposure that gives you the cleanest white in the brightest part of the print while still holding a trace of detail in the important highlights. Call that value your grade 0 time, say 12 seconds.
3. Switch to a grade 5 filter.
4. Run another test strip on a different area, or on a fresh sheet, with the grade 0 exposure already "burned in" underneath, and add grade 5 increments on top. Find the exposure that gives rich, deep shadows without blocking up the midtones.
5. Combine both exposures on a fresh sheet and develop.

The first combined print usually isn't perfect. But you know exactly what to adjust: if the highlights lack substance, add time at grade 0. If the shadows aren't deep enough, add time at grade 5. The two variables are independent, and that's the real advantage.

There's another practical benefit worth mentioning: split-grade printing makes it straightforward to dodge specific areas during the soft exposure to hold highlight detail in just those zones, without affecting shadow rendering at all.

Reading contrast by subject

Filters and split-grade technique are tools, not recipes. Reading the negative well is still the core skill. Here's how contrast choices play out in practice for a few common subject types.

Portraits

A portrait in soft natural light with a neutral background usually prints well around grade 2 or 2.5. The goal is to preserve gradation in skin tones: too much contrast and the skin loses its transitions, eyes go harsh, hair blocks up. A slightly overexposed negative, which is common in portrait work, will call for a lower grade than usual, maybe 1.5 or even 1, just to keep the midtones from compressing.

For a portrait shot in raking light or very contrasty conditions, split-grade can help a lot. The soft exposure holds the skin in the lit zone, and the hard exposure punches up the shadow side and gives the whole image some depth. The result can feel more convincing than just slamming a grade 3 at it.

Landscapes

Landscape negatives, especially from overcast or hazy days, tend to be flat. Grade 3 or 4 is common, sometimes 4.5 for coastal fog that's compressed everything into a narrow tonal range. If the sky holds good detail in the negative but the foreground is dark, split-grade lets you work them separately: burn the sky with a soft filter to bring out cloud texture, then work the dark ground areas with a hard filter.

For landscapes shot in strong sun with extreme shadow-to-highlight contrast, the logic sometimes reverses. An overdeveloped, high-contrast negative may want grade 1 or 2, with local dodging in the shadow areas to pull out whatever detail is there.

Architecture

Architecture is particular because of all those straight lines, flat surfaces, and hard transitions. Too hard a grade on a concrete facade can go metallic and cold, even aggressive. Too soft and you lose the texture that makes a building readable.

Interior architecture with bright windows in the frame is almost a textbook case for split-grade printing. Without separate highlight management, the window reveal disappears and you're left with featureless white rectangles. A long soft exposure, say grade 0 for 15 to 20 seconds, to reach into the sky outside, then a short hard exposure, grade 5 for 5 seconds, to anchor the interior shadows.

A few situations that catch people out

Changing filters without checking for movement. If your enlarger doesn't have a proper filter drawer and you're sliding filters in by hand below the lens, make sure the negative stays perfectly still between the two exposures. Any shift at all gives you a slight directional blur that shows up first in fine detail.

Development time. Stick to the manufacturer's recommended times. For Ilford Multigrade paper that's generally 60 to 90 seconds in a standard developer at 20°C (68°F). A print pulled early because it looks right under the inspection light will darken as it dries.

Going further

If you want to go deeper on split-grade technique, "Way Beyond Monochrome" by Ralph Lambrecht and Chris Woodhouse is a solid reference, with detailed sequences covering variable contrast and two-stage exposure.

For filters, the Ilford Multigrade below-lens filter kit is the most logical starting point if you're printing on Ilford paper: the filters are calibrated as a set, sold with a filter holder, and available in 8.9 cm to fit most common enlarging lenses.

If you're working with a colour head enlarger (DeVere, Durst, Meopta, LPL), you can reproduce the full multigrade range using just the magenta and yellow dials without buying a single filter. Ilford publishes grade-to-filtration conversion tables in their technical documentation. It's often more practical in the darkroom since there's nothing to pull out or put back between the two exposures.

Sources

• https://www.ilfordphoto.com/multigrade-filter-above-lens-kit
• https://www.ilfordphoto.com/multigrade-filter-below-lens-kit
• https://www.ilfordphoto.com/wp/wp-content/uploads/2017/04/Making-your-first-print.pdf
• https://www.35mmc.com/27/04/2020/split-grade-printing-darkroom-technique-part-4-by-sroyon-mukherjee/
• https://www.lomography.com/school/what-is-split-grade-printing-fa-51eovnlq
• https://www.freestylephoto.com/3661949-Kodak-Polymax-150mm-x-150mm-Filters-(Set-of-12)
• https://amateurphotographer.com/technique/expert_advice/essential-guide-to-darkroom-printing/