Natural blue dyes are rare. Most of the blues our chemist collaborators have analyzed from the robes in our collection are synthetic. Historical and oral sources suggest indigo, copper, or “blue clay” made blue and green dyes, too.
Indigo could have been a trade item or boiled from trade cloth in a vat of urine. We failed to boil indigo from yarn using urine, but succeeded using equivalent laboratory chemicals. The resulting dyebath made a pale blue. We also experimented with overdyeing natural yellows with indigo to give various greens.
A piece of copper pipe in a jar of ammonia will give a vibrant cobalt-blue solution and vividly-colored corrosion products on the copper. But these colors are not the final dye colors. Yarn dipped in copper/ammonia solution turns a dull gray-green. Subsequent dipping into vinegar immediately gives a pleasing minty-green color.
The “blue clay” remains a mystery. We wondered if it might be vivianite, a blue clay used to make a paint pigment. After much failed experimentation, it seems unlikely. In general, minerals that make good pigments for paints do not make good dyes because their particle size is too large and cannot be bonded easily to the fiber.
Some mushrooms and lichens are said to yield blue dyes. Lepraria lichen may have been used on vest SJ-I-A-48. While there are no historical accounts of mushrooms or lichens used for blue/green dyes, weavers have always been open to innovations in dyeing and continue to explore natural options from the land.
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From the exhibition The Spirit Wraps Around You (May 8–October 9, 2021 at the Alaska State Museum):
All unattributed materials listed come from the Alaska State Museum conservation lab and include the after-hours activities of conservator Ellen Carrlee.