Imposition: Preparing to print

The type is moved, in chunks, into a metal frame called a chase, like this empty one, left. The chase needs to be lying on a very flat surface so that the type will be perfectly level. A machine-ground metal slab called an imposing stone is the traditional choice but you can use a glass slab instead.

Thin strips of metal, called leads, are used to add extra space between lines. Furniture is the name for larger metal strips and wooden ones too; they're used to take up some of the empty space in the chase, around the text. Square and rectangular metal shapes called quotes are also used to take up some of this blank space.

Expanding metal quoins (pictured below right) are used to lock everything into place securely and the surface of the type is gently tapped (planed) to make doubly sure that it's even. This completed forme can now be picked up and – with a bit of luck – the type won't fall out and land on the compositor's foot.

At this point, a proof can be taken with a hand roller. It's easier to see mistakes on paper. The most common error is a letter in the wrong place – perhaps because it had been put in the wrong compartment of the type case. Sometimes a single piece of type, or sort, will need replacing because it's worn or damaged.

• Getting Started: Imposition
• NEW: 'Other Voices of the British Isles' £16.00
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• Links to Other Presses