The difficulty of repeating by machine what a hand can adjust

Picture Karami weaving done by hand. Watching the state of the thread, the weaver moves the thread to be crossed and passes the weft. Where it catches, a hand steadies it; where it is too tight, the tension is eased. Being able to check pick by pick is the great strength of weaving by hand.

Sensing the nature of the thread and answering it on the spot: it is this flexibility that allows even complex crossings to be formed one by one. By hand, lifting a thread a little, or changing the order of movements, can solve a problem there and then.

What is difficult on a power loom is to make that small, in-the-moment adjustment work without a hand intervening at every pick. Cross the warp, open the space for the weft, beat the weft in, move to the next action — and through that sequence the tension of the thread has to be held right as well.

In Karami weaving, slack causes trouble too. Research at the Aichi Center for Industry and Science Technology using paper yarn reports the problem of a loose warp thread catching between the heddles and breaking. Pulling the thread tighter is not the answer either; conditions have to be found that suit the material.

Aichi Center for Industry and Science Technology, Research Report 2009, pp. 130–131

From mechanising part of the process to continuous automatic running: the smaller the range a person makes up for in the moment, the more that adjustment has to be built into the threading, the placing of the parts, the timing of the movements and the tension settings. The difficulty of automation lies in replacing a person's responsiveness with a mechanism that holds, repeat after repeat.

And the result of an adjustment shows not in one interlacing but across the full width and length of the cloth. From the first pick through all the repeats that follow, the delicate crossing has to stay even. Creating those conditions, watching the state of the work, and stepping in where needed — that is the skill of the person who runs a power loom.

In every length a machine weaves, the judgement and ingenuity accumulated on the floor are alive. Passing that knowledge from person to person is what will carry the production of Karami weaving into the future.