page fifty-seven

The Forge

Yesterday the light had to be judged by eye through a glass roof. Today it is heat. A village smithy on a working morning some time between 1790 and 1889, with no thermometer in it: only the colour of the iron, the daylight coming in at the door that changes how that colour looks, and three customers who will call at the hour they were promised.

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Now—
Shop clock—
Daylight—
The fire—
The work—
The order—
Calling at—
Purse—

Keys: F fire or anvil, hold B for the bellows, space to strike, S sand, Q quench, C clean the fire.

    Day
    —

    Every day is a different village, sky, coal, iron, steel and slate of orders.

    What is real here and what is not

    The heats, the colours and the order of the work are real. The village, the stock and the customers are the day's number; the fire and the cooling of the iron are a model, sized to give the right sort of seconds.

    1. 01

      Heat by colour

      Before pyrometers a smith knew heat only by the colour of the iron, and every smithy was kept dim for that reason: in daylight a dull red barely shows and a yellow looks like an orange. Smiths named the heats by what they saw (black, dull red, cherry, orange, yellow, white, sparkling) and worked to them. The page draws the iron as a hot body seen by an eye adapted to the light in the shop, so the same heat looks different at seven and at noon, and when a cloud goes over the door.

    2. 02

      Fire welding

      Wrought iron welds to itself when both faces are white hot and clean. The scarfed ends are sprinkled with sand (or borax for steel), which melts into a glassy flux that dissolves the scale; the first blow must land within seconds of the iron leaving the fire. A little hotter still and the iron burns, throwing white star-shaped sparks. The welding heat sits in a band only a hundred degrees or so below that, and a poor fire choked with clinker may never reach it.

    3. 03

      Hardening and tempering

      Carbon steel quenched from just above its hardening heat (a cherry red, near 760 to 800°C) turns glass hard and brittle; quenched from too hot it is coarse-grained and may crack, from too cold it stays soft. It is then rubbed bright and gently reheated from the back: thin oxide films run over the face in order, straw, brown, purple, blue, each meaning a softer, tougher temper, and the smith quenches when the colour he wants reaches the edge. Razors and knives were left at straw, chisels at brown or purple, springs at blue.

    4. 04

      What the page simplifies

      The iron is one temperature from end to end (except while tempering), the fire is one number, and every blow at a good heat moves the work by the same amount. The welding and burning heats, the steel's hardening heat and the coal's best fire are the day's number within believable ranges, not the figures for any real brand. The shop clock runs twenty times as fast as yours, and there is no striker to swing the sledge for you.

    Fifty-seven rooms, and one number doing all the work. Today it lights a fire, opens a door on to the day's weather and decides how hot the iron in the rack has to be before it will weld.