Materials
Prior to the middle of the 19th century, most Columbia River twined bags were made using Indian hemp (Apocynum cannabinum) for their foundation fabrics and various natural grasses (such as bear grass, Xerophyllum tenax) for their false-embroidered designs. After 1860 or so, many weavers began using cornhusk for the foundation fabric, which was cheaper and stronger than hemp. This change in material usage over time is one reason that Dr. Mary Schlick dates the manufacture of the repatriated bag to the early 19th century:
Women of the Plateau spin the outer fibers of the giant dogbane (Apocynum cannibinum, known generally as Indian hemp) on their knees into a strong 2-ply string or twine that forms the basic structure of the bag – the darkest background area. The design areas are woven using a strong species of unknown grass, possibly bear grass (Xerophyllum tenax), which is known to have been used in these earlier bags. This use of grass predates the later adoption of cornhusk (Zea mays) for the designs. The subdued colors in the designs suggest an early date of manufacture [for the repatriated bag], probably before the 1840s.
Toward the end of the 19th century, commercially produced cotton string became widely available as a third type of foundation material, and after 1880 glass beads emerged as an increasingly popular decorative material. Additional substances that are often seen in twined bags include leather, which was typically used for edging and for carrying straps, wool, and various types of trade cloth like cottons, flannels, and velvets, which were used for both interior linings and exterior finishings.
Traditionally, the dyes that were used to color twined bags were all derived from natural plant materials. Contrast was also produced through exposure to the sun. However, during the latter half of the 19th century, many weavers began to use synthetic chemical dyes as well, which provided a broader range of brighter, more vivid hues.
The yellow/orange color could have been obtained from the roots of the sand dock (Rumex venosus). I believe that the two natural tones of the false embroidery in this bag are achieved by using grass which has been dried in the shade (the darker) and in the sun (the lighter). Although not evident on this bag, reds from raveled wool began to appear in twined hats early in the 19th century and probably also were incorporated in other early post-contact weaving.