Shed (weaving) - Shedding Device

Shedding Device

The type of device that is used to raise and lower the shed differs on the type of loom. With a tablet loom the sheds are raised and lowered by rotating the tablets, or cards. In a floor loom the shed is created by the harnesses. Inkle looms have one of the more primitive shedding devices, where there is one set of heddles and the shed is created by hand.

Originally there was no shed, and the weft was inserted into the warp by picking the warp threads up individually, as is done in tapestry weaving. After each weft thread is woven the warp threads had to be picked out and lifted again, which made the process slow. To speed up the process various devices were developed to create a reproducible shed, so that the weft could be passed between the separated threads, and so the threads would not have to be separated individually each time. The first type of shedding device was called a shed-rod. It was a rod inserted into the warp to ease in weaving, and came about at the same time as the heddle. Threads were alternated over and under the rod, and the threads that went under the rod went through string heddles attached to a bar. The shed was created in two ways:by raising the shed-rod, and by lifting the heddles. The shed-rod was an invention of eastern origin, and was introduced to Europe via Egypt in the first century AD. The Romans used it for both plain weave and twill.

After the shed-rod came the rigid heddle loom, where the shed is created by raising or lowering the rigid heddle. As the loom progressed, the shed-rod was replaced by a second set of heddles, for a total of two shafts with heddles. Eventually looms like the modern floor loom were developed, where there are many shafts which can be raised to create the shed.