Robots and Machines

A bottle of paint hangs on a string above a big sheet of paper, and once it's swinging, it draws, looping and crossing in patterns no hand could manage. We open the theme with it because nothing else announces "this week is different" quite so well.

We built our pendulum frames from PVC pipe, with an elbow or T-joint at the top for a high, steady hanging point, and they've survived years of enthusiastic use. A sturdy tripod works too, or a broom handle wedged between two chair backs, as long as the hanging point is high and rock-solid, because a wobbly frame turns the loops to scribble. At the studio we run three frames in a row along one long drop sheet, one colour per frame, and the artists carry their paper down the line from colour to colour. The layering is where the patterns get rich, and you'll never have to wash out a bottle mid-session!

The bottles are squeezy sauce bottles, the kind with the little flip-top lid (so handy, because the lid stays shut while you fill and reposition, and only opens once the bottle is properly swinging). Fill each one with paint at roughly the flow of thin cream: too thick and it clogs mid-swing, too watery and it floods the paper. If a colour is being stubborn and thick, a small squeeze of dishwashing detergent loosens it beautifully. And hang each bottle from a single tie point so it can rotate as it swings, because that rotation is what turns a flat back-and-forth line into spirograph loops.

Smudge Tip: Rig this on a well-covered floor, never a table. We use a thick canvas drop sheet with a plastic backing, laid far wider than seems reasonable, because a swinging bottle flings paint a remarkable distance, and the big swing is the joy of it. Protect everything generously, then let them swing with gusto.

Tape the paper down, flip the lid open, draw the bottle back, and let go. The paint streams out in a moving line, the bottle slowly rotates, and the loops drift and overlap into a pattern nobody could draw freehand. Every launch is a fresh experiment: a straight pull-back gives long ovals, a sideways push sends it circling, and the artists very quickly start placing bets on what each launch will do.

When a pattern wants a second colour, the artist picks their paper up and moves one frame down the line, and the new loops settle over the old ones. Between papers and turns, snap the lid shut, still the bottle, and reset.

It's also the experience for the kids who are certain they can't draw, because the machine makes the marks and the artist still makes every decision: which colour next, which way to launch, when a page is finished.

The pendulum rule (worth telling the kids)

The story goes that Galileo, bored in Pisa cathedral, watched a hanging lamp swing and timed it against his own pulse. Big swing or small swing, the time never changed. A pendulum's timing cares about one thing only: the length of the string. Not the weight, not how hard you push. Which means the kids can test a 400-year-old discovery with a paint bottle: shorten the string and the loops come fast and tight, lengthen it and they turn slow and lazy.

Run one enormous shared sheet across the week, every session's colours layering over the last, then hang the finished piece as the theme's grand finale.

Try white paint on black paper for prints that look like star maps.

Set the paper off-centre, or on an angle, so the pattern runs off the edge and the composition surprises everyone.