Right From The Start

Information provided by Marcy Petrini

Doubling the Width of the Loom

On 4 shafts, it is possible to double the width of the loom by weaving double weave. The principle is elegantly simple: the "front" loom weaves the top layer, the "back" loom weaves the bottom layer. To weave the top layer, the shafts are alternated as usual. To weave the bottom layer, the shafts are also alternated as usual, but the top layer must be out of the way, and thus it is raised.

A single continuous weft joins the two layers on one side. One shot is woven for each layer, before proceeding to the second shot; otherwise, it would be impossible to beat the weft in place.

The sett for double weave is twice that of each layer. For example, plain weave with 5/2 cotton is the sett at 18 epi. In double weave, the top layer is sett at 18 epi, the bottom layer is sett at 18 epi, for a total of 36 epi.

Because the sett is rather dense, the threads for the top layer are alternated with those of the bottom layer in the threading. A straight draw is used, 1, 2, 3, 4 repeat.

The threading proceed as usual, but in treadling, it is helpful to think of the threading as top (T) and bottom (B):

			4B
		3T
	2B
1T

Then the treadling is shafts 1 versus 3 to weave the top layer; and shafts 2 versus 4 to weave the bottom layer, while raising threads on shafts 1 and 3 out of the way.

For ease of weaving, the loom can be tied-up as follows:

Sinking Shed	Treadle #	Rising Shed
2 & 3 & 4	1	1
1 & 2 & 4	2	1 & 2 & 3
4	3	1 & 3 & 4
2	4	3

The treadling proceeds as follows, with one weft:

Shot #1, treadle # 1	first shot of top layer
Shot #2, treadle # 2	first shot of bottom layer, top layer out of the way
Shot #3, treadle # 3	second shot of bottom layer, top layer out of the way
Shot #4, treadle # 4	second shot of top layer

The fabric is joined at one side, the side opposite where the shuttle enters the first shot of the top layer. For example, after the first treadle is activated, if the weft enters on the right, and travels from right to left, the fabric will be joined at the left.

Two precautions must be taken when weaving:

• It is particularly important that the shed be open clearly and cleanly, and that the weft is not caught in both layers. If this happens, the two layers will be joined in that spot somewhere in the fabric. This can be cut and mended off the loom, but it is much easier to avoid the mistake. A mirror (like a compact make-up mirror) mounted on the side of the beater is particularly helpful to allow checking for a clear shed.
• Draw-in at the side where the two layers are joined results in a denser fabric in the middle. Not only can this be a particularly noticeable thicker stripe in the middle of the fabric, but it can also cause tension problems when weaving, resulting in uneven beat and broken threads. If excessive draw-in cannot be avoided, the sett can be slightly decreased for the last ½" or so of the warp that will be the middle of the fabric.

For an occasional wider piece, double weave is a nice solution for a loom of any width.

With double weave, a tube can be woven by joining the fabric on both sides. This is done by switching shots # 2 and # 3 above. Double weave can also be woven by switching the top and bottom layers, and by bringing threads from the bottom layer to the top layer to form figures, using a pick up stick. For more options, see Loom-Controlled Double Weave and More Loom-Controlled Double Weave by Paul O'Connor, available on HyperTextures.