How bone china is made

The Worcester vase above, made about 1872, is painted with the making of porcelain itself: the kiln, and the painters at work. The stages it shows are still recognisable in a modern factory.

Eight stages

1. 1 · BodyPreparing the bodyCalcium phosphate, china clay and china stone are mixed with water, sieved, and passed over magnets to remove iron. The mixture is kept liquid for casting or pressed into a plastic body.
2. 2 · ShapeJiggering, jollying and castingPlates are formed over a spinning plaster mould with a profile tool; cups and bowls inside one. Teapots, jugs and other hollow shapes are slip cast in plaster moulds.
3. 3 · FinishFettling and spongingSeams are trimmed and surfaces sponged smooth. Handles are made separately and fixed by hand.
4. 4 · FireBiscuit firing, highFired on shaped supports until the body vitrifies, shrinking and turning dense and translucent.
5. 5 · GlazeGlazingThe fired body is dipped or sprayed with glaze formulated to meet food-contact limits.
6. 6 · FireGlost firing, lowerThe glaze melts into a smooth glassy skin.
7. 7 · DecorateDecorationColours, prints and precious metals are applied and fired on — sometimes several times.
8. 8 · SelectSelectionEvery piece is inspected. Minor cosmetic faults are graded as seconds; damaged pieces are rejected.

The hand and the machine

Modern bone china works use automated jiggers, pressure casting and computer-controlled kilns. Fine pieces still pass through many hands: Dibbern says more than three-quarters of its production involves manual work and that its plates are still turned rather than pressed. At the other end of the scale, the largest Asian factories produce tens of thousands of pieces a day. Both are bone china; the difference is in scale, finish and price.