Clay Marbles

Wedge a fist of clay until it is uniform, and cut it through with a wire to check for air pockets. An air bubble in a solid ball is the classic reason a piece bursts in the kiln.

Roll a coil about 16 mm thick and cut it into equal lengths. Equal blanks give equal marbles, which matters in a game where they are matched against each other.

Weigh five blanks and check they are within a gram of each other. Adjust the coil thickness rather than trying to fix it later.

Roll each piece between your palms in circles until it is roughly spherical. This gets you to about ninety per cent and no further — palms are not flat and they follow the shape they are given.

Put the ball between two flat boards and move the top one in circles with light pressure. The ball rolls on a constantly changing axis, so every high point gets flattened in turn and the shape converges on a true sphere. This is the whole technique.

Roll each marble down a sloping board. A true one runs straight; an untrue one veers, every time, in the same direction. Fix it now while it is soft.

Roll a marble lightly on a textured surface, or press in a spiral of coloured slip. Keep the surface smooth — a raised decoration wears off in play and unbalances the ball.

Dry the marbles on a rack for several days, turning them daily. A ball drying on one spot dries unevenly there and comes out slightly flat on that side.

Hold one to your cheek. If it feels cool, it still holds water. A solid ball with water still in it can explode in the kiln and damage everything around it.

Fire the marbles sitting in a shallow bisque dish or on a bed of sand so they cannot roll off the shelf. Loose spheres on a flat shelf move as the kiln heats.

Fire to the top of your clay's range rather than a low bisque. Marbles are struck against each other constantly, and a soft-fired marble chips on the first good hit.

Take one marble and knock it hard against another, repeatedly, until something chips. Knowing what your marbles survive is worth losing one to find out.

Sort the finished marbles by diameter with a caliper and keep the matched ones together. Mixed sizes make an unfair game — a bigger marble knocks a smaller one out of a ring more easily.

Draw a circle about a metre across, put the target marbles inside it and flick your shooter from outside the line. Marbles knocked out are won. The rules vary everywhere; the ring is the constant.

Everywhere, and very old. Small clay and stone balls turn up on archaeological sites across the world, from the ancient Near East through Egypt, Greece and Rome and on into the medieval and early modern periods. Clay is the obvious material: it is free, it needs no lathe, and the firing that makes a pot makes a marble at the same time.

The interpretation problem. A small fired clay ball is not necessarily a toy. Excavated spheres have been read as gaming pieces, sling shot, counting tokens, loom weight blanks and pot-making waste. Without a context that shows how they were used — found in a group by a hearth, or with a board, or in a child's grave — the object alone does not settle it. Any confident claim that a particular find is a marble deserves a second look.

Why the two-board trick works. Rolling a ball between two flat surfaces means it cannot keep the same axis of rotation for long. Whatever point is highest gets pressed down as it comes round, and repeating that thousands of times drives the shape toward a sphere without anybody having to measure anything. The same principle is used industrially: ball bearings are finished by lapping balls between rotating grooved plates.

Then glass and industry. Marbles were made in stone and clay by hand for millennia. German glassmakers made them individually with marble scissors in the nineteenth century, and around 1900 American machine production made cheap glass marbles universal — which is when the clay marble, along with hand-made everything else, stopped being the ordinary thing and became the historic one.