Yoshiko I. Wada wrote the follow comment in response to the latest blog post. She was a very important part of this experience and I thought her words, with additional insight, deserved their own spot and thus the following:
“This is a friend of Catharine’s, Yoshiko I. Wada from slowfiberstudios.com and naturaldyeworkshop.com, where we re-blog Catharine’s blog in our Dye Nerds’ Blog. Since the person in charge of our blog is on vacation until the end January and I was g Japanese to English translator for Dr. Yamazaki I am jumping in for some additional thoughts and information.
The Jinze Art Centre in Shanghai and Slow Fiber Studios in Berkely, CA organized the workshops with Japanese masters working with my colleague Edith Cheung who is in charge of the textile program there.

RE: Camellia ash (椿灰汁) since the Asuka Period (538 to 710 ) and Nara Period (AD 710 to 794) documents recorded that the Japanese dyers used the liquid strained from the camellia ash as a vehicle to shift pH and at the same time to access its alum as a mordant. Camellia is a plant which is called bio-accumulator of aluminum similar to symplocos, lycopodium and miconia. Those plants have been used as mordants in Southeast Asia, northern Europe, and Mexico respectively. The anthology of poems Man’yōshū 万葉集 literally means “Collection of Ten Thousand Leaves” contains many poems associating with purple colors (murasaki) and gromwell roots (shikon) and madder as well as camellia ash. The collection contains poems ranging from AD 347 (poems #85–89) through 759 (#4516), the bulk of them representing the period after AD 600.

Catharine: At the bottom is the love poem by Princess Nukata I told you about. And it starts with madder (akane) as a pillow word but scene is the gromewll field (known to belong to Tenchi Emperor). Murasaki is purple and the plant was a precious medicinal herbs. From the poem, the guarded field may have hosted wild gromwell plants like the Super Gromwell Roots that Edith found in Hong Kong where herbalist told her “only the very best is found in Hong Kong.”

The wild purple roots were so strange looking compared to the ones imported from China that Dr. Yamazaki uses in Japan that it gave him such worries during the class. He thought after making the students knead the soaked roots for 2 hours on their knees on the floor, only grey pale purple is achieved.
On the contrary, we achieved the most beautiful purple even with limited time we had to process it all. Did he mention that in his studio, he kneads the roots a few times in the morning and some more in the afternoon to get maximum colorants from the plants? And he repeats dyeing, middle mordanting, and dyeing, many times in a few days to get saturated deep purple? He did say the purple dye extracted in this way has much more complexity and depth than the easy extraction with alcohol.
Yoshiko I. Wada

茜さす紫野行き標野(しめの)行き野守(のもり)は見ずや君が袖振る 額田王(ぬかたのおおきみ).
訳)茜色を帯びる紫草が生い茂る(天智天皇の御料地である)野を行き,貴方は袖を振る.野守りが見とがめはしないでしょうか?