Light Side, Shadow Side

The idea: form

Form is a three-dimensional element with height, width and depth, such as a cube, a sphere or a cylinder. On a flat surface form can only be implied, most often by light and shadow, overlap and perspective.

In a notan: A notan is as flat as art gets: two values, no gradual shading, one plane. That makes it a good place to learn how form is implied. With no gradient to lean on, you must decide where the lit side of a solid ends and its shadow side begins, and make that boundary a cut. The fold helps. A cut that touches the edge of the sheet lands beside its hole as a mirror image, and the pair read as one solid lit from one side: a disc becomes a half-lit ball, a four-sided face and its twin the two sides of a box. Set the sheet to a half-tone, and it becomes the gray wall against which light and shadow both read.

Form is the one element a notan cannot literally have. Paper laid flat has no depth, and two values leave no room for the slow gradient a painter uses to turn a ball. Yet a good notan can look solid. The trick, which printmakers have used for centuries, is to give up the gradient and keep only the boundary where light turns to shadow. A ball lit from the left is a light shape and a dark crescent. A box is two or three flat faces, each a single value. A can is a light band beside a dark band, with a curved end. Place the boundary well, and the eye supplies the roundness.

The fold gives you two more tools. A cut that touches the edge of the sheet lands beside its hole as a mirror image, so the pair make one shape divided exactly down the middle into two values: the simplest model of a solid lit from one side. And the three colors can be set as three values of one hue, so the uncut sheet becomes a half-tone setting. Where two areas of the same value meet, the edge between them is lost and the viewer must complete it. Artists lose edges on purpose: a form that is not outlined everywhere seems to sit in real light.

Art history

Artists have implied form without gradual shading for as long as there has been printing, because a relief block either lays down ink or leaves the paper bare. Renaissance printmakers stacked a few flat tones; a photographer found flat shapes in solid things; a painter and a Bauhaus teacher built volume from stripes and bare lines. What each shares with a notan is a decision about the boundary: exactly where the light stops.

• Ugo da Carpi, after Parmigianino Diogenes, c. 1527–30

  An early chiaroscuro woodcut, printed from four blocks, one for each tone. There is no smooth shading anywhere: the seated philosopher, his barrel and the plucked hen behind him are built from a few flat tones laid edge to edge, and the edges do the modeling. Count the tones, then find where light turns to shadow.

• Paul Strand Abstraction, Porch Shadows, Twin Lakes, Connecticut, 1916

  Strand tipped a round porch table onto its side in strong sun and pointed his camera down at it, so that table and shadows flatten into bands and wedges of light and dark. It runs the notan process in reverse, turning solid things into flat shapes.

• Victor Vasarely Zebra, c. 1937–38

  Two zebras entwine on a black ground, made of nothing but curving black and white stripes, with no outline and no shading. Where the stripes bend, the bodies turn; where they bunch, a flank rounds away. The curve of a line alone can carry volume, a lesson for any notan built from slits and strips.

• Josef Albers Structural Constellation, c. 1950 Josef and Anni Albers Foundation, Bethany, Connecticut

  Albers had thin white lines machine-engraved into black plastic to draw solids that will not settle: a plane that reads as facing up can flip, a moment later, to facing down. Two values and a few lines are enough to make the eye build volume, and to make it doubt what it built.

Design today

Designers imply form with as little as they can. Saul Bass’s striped globe for AT&T, designed in 1983, is a flat circle crossed by horizontal bands whose widths swell and thin across it; the change reads as light sliding over a sphere, with no shading at all. The puzzle game Monument Valley (ustwo games, 2014) builds impossible buildings from faces of flat color, in a manner often compared to M. C. Escher’s prints.

Interfaces have had the same argument. Early smartphone apps imitated leather and glass with heavy shading; the flat design that followed stripped it away. Google’s Material Design, introduced in 2014, found a middle path in paper: flat surfaces at different heights, their depth shown by soft shadows. During Replay, each piece casts a shadow while it is lifted off the sheet, the one moment a notan has real depth.

Warm-up

Darken the room and light a white ball, a box and a paper cup from one side. Squint until the details disappear and each object breaks into a few flat patches. On scrap paper, draw only the boundary where light turns to shadow on each, and the outline of the shadow it casts. The boundary is a curve on the ball, an edge on the box and a straight line on the cup.

In the studio

Make it in Studio Notan, where every cut can be moved, refolded and undone.

1. Set up three values. Open the studio, go to the Color tab, select the ‘Front’ card and give it a color of middle value, such as a medium blue. Lock it with its padlock and press ‘Mono’ under ‘Harmonies’. The Monochromatic harmony makes the back darker and the ground lighter: holes will show the light, pieces the shadow, and the uncut sheet the half-tone between.
2. Make a ball lit from the left. With the Pen, click a point on the right edge of the sheet, where it snaps; press and drag at the point furthest into the sheet to pull out handles; click a third point back on the edge; close on the first point. Fold it over the right edge. Hole and piece join into one round shape, light on the left and dark on the right, like a half moon.
3. Make a box below it. With the Pen, click on the right edge, click a point inside the sheet a little lower, click straight below that point with Shift held, click back on the edge a little lower still, and close. Fold it right. Hole and piece are the two sides of a box seen corner-on at eye level, light on the left and dark on the right.
4. Make a can on the left edge with the Draw tool. Start just outside the sheet, draw the right half of a can’s outline, curving down to its side, straight down, and curving back, and finish just outside the sheet. Only paper is cut, so the hole’s side on the edge comes out straight. Fold it left: light band, dark band, curved ends. But every form that straddles the left edge is lit from the right. To keep one lamp, which edges may your solids use?
5. Find a lost edge. With Draw, draw a crescent inside the sheet, the lit sliver of a ball whose light comes from the left, and fold it over the right edge. Inside, it reads as light catching a ball whose shadow side melts into the paper. Outside, its dark piece is the shadow side of a ball whose lit side melts into the ground, still lit from the left: the mirror flips the crescent, and the change to dark flips it back. Press Undo, which reopens the chooser, and fold it over the top edge instead. Where is the light now?
6. Compare two values with three. Press ‘Mono’ again to release it, unlock the front, then type 000 in the Front and Back hex fields and FFF in Ground. Which forms still read, and which needed the half-tone sheet behind them?
7. Press Replay and watch the folds. While each piece is in the air the studio catches light on it and gives it a shadow. Your finished forms must hold up without those frames.

With paper and paint: Paint the Gradient, Cut the Boundary

A brush lets light turn to shadow slowly: you can blend one gray into the next until no edge is left. A blade cannot blend. It puts the whole turn from light to shadow on a single line, and once the cut is made it stays made. Painting a ball both ways, under the same lamp, shows exactly what a notan gives up and what it keeps, the trade Ugo da Carpi made when he printed Diogenes from a few flat tones. Mixing your own grays also teaches something the Mono button hides: where the middle value really sits, and how paint changes as it dries.

1. Mix a value scale. On the strip of watercolor paper, paint five squares in a row: pure white, a light gray, a middle gray, a dark gray and pure black. Add black to white a little at a time, because a small touch of black darkens white quickly. Judge the grays only when they are dry: gouache shifts as it dries, light mixtures a little darker and dark ones a little lighter.
2. Paint a ball the painter’s way. Set the white ball under the lamp, lit from the left. On the scrap of watercolor paper, draw a circle and paint it with your grays, light on the left and turning to dark on the right, blending each gray into the next while the paint is wet. This slow gradient is what a notan must give up.
3. Paint the sheet. Tape the black square down by its corners and paint one side with the middle gray, in two thin, even coats, letting the first dry before the second. The gray side is the front, a half-tone sheet; the black side is the back, which only the flipped pieces will show; the white paper is the ground, the light. These are the three values of the Mono harmony, mixed by hand. Let the sheet dry right through.
4. Cut a ball. Draw a half circle against the right edge of the sheet, its flat side on the edge, and cut it out. Lay the sheet, gray side up, on the white ground, turn the piece over the right edge, black side up, and set it against its hole. White half and black half join into one round shape: a ball lit from the left, its whole turn from light to shadow on one straight line.
5. Cut a box. Below the ball, cut a four-sided shape against the same edge, its inner side upright and a little shorter than its side on the edge. Turn it out the same way. The white face and the black face become two sides of a box seen corner-on, lit from the left.
6. Glue the sheet to the ground, then each piece against its hole. Stand the painted ball beside the cut one under the lamp and step back across the room. The painted ball turns slowly; the cut ball turns all at once, on a line you chose. Which reads as rounder from far away, and which from close up?

Take care: Let every coat dry right through before you cut, because damp paper tears under a blade; choose paints with the ACMI AP seal, and rinse brushes before the paint dries in them. Cut on a self-healing mat, away from your body, with the hand that holds the ruler well clear of the blade’s path, and keep paper away from a hot lamp bulb.

Take it further

Take the problem into real space. With a craft knife, cut three sides of a rectangle in a card and fold the flap along the fourth. Laid flat, it is a hole and its piece; stopped at a right angle, it stands up and casts a real shadow. Taken much further, this cut-and-fold idea is origamic architecture, the pop-up technique the architect Masahiro Chatani developed in Japan in the early 1980s.

Reflect

• Where in your still life does a single boundary between light and dark do the work that shading would do in a drawing?
• When you folded the crescent over the top edge, the light seemed to change sides. Why does the choice of edge matter?
• Which lost edge is the eye most willing to complete, and which one did you have to rescue?
• How does Strand’s photograph of porch shadows run your process in reverse?

What to look for

• Each solid reads as a ball, a box or a can without any gradual shading.
• Light and shadow are placed consistently, so a viewer can point to where the light comes from.
• At least one form is built from a cut that touches the edge, its hole and piece reading as two sides of one solid.
• The learner can name a lost edge and explain why the form survives it.
• The painted ball and the cut ball are compared under the same lamp, and the learner can say what the cut gave up and what it kept.