Techniques
Plateau twined bags are traditionally woven by hand, without the use of looms or any other special equipment. Sometimes, though, weavers use a slat or stick at the bottom of the bag in order to prevent the warps from twisting and distorting the textile’s final shape. The weaver, usually a woman, sits on the ground and holds the raw materials in her lap as she intertwines the warps (vertical cords) with the wefts (horizontal cords).
Of the repatriated bag, Dr. Schlick said:
The technique used in weaving the bag is plain twining with the decorative areas achieved in external weft wrap (commonly known as false embroidery). David W. Fraser, in A Guide to Weft Twining (1989), attributes this particular variation of the technique to Nez Perce, but Yakama, Warm Springs, Umatilla and other related weavers also used it extensively to make the bags they needed for carrying and storing dried foods and other necessary items. The tight fabric produced by this technique created a dust-free container which was important in this dry region. False embroidery is practiced today, but only for making handbags and smaller pieces.
Many Columbia River twined bags employ false embroidery, the decorative technique mentioned above. In this technique, supplementary wefts beyond those needed to form the bag’s basic structure are woven into the fabric to create a decorative design. The number and direction of these supplementary wefts directly affects the complexity and pattern of the final design.
Besides false embroidery, the other major decorative technique employed in Columbia River bags is beading. Beaded bags are made by stringing together rows of beads onto very fine threads, which are in turn sewn onto the bag’s foundation structure. Because beading is an extremely time-consuming process, and because the resulting bags are so delicate and fragile, this technique has historically been employed much less frequently than false embroidery.
Along with basic construction and decoration, Dr. Schlick commented on the finishing of the bag:
The top edge of this bag is finished in a technique that I've seen only rarely on the flat bags. Described as a "self-edge," [sic, usually called a selvage, derived from “self-finished edge”] the technique produces a braided effect and commonly is used on the round bags made by the Upper Chinookan people (Wasco/Wishxam) of the Mid-Columbia River. The majority of the flat twined storage bags such as this one are finished by "twining off" -- employing the twining strands to lock the bound-off wefts in place."