Sukumo dye

I have not yet attempted this, but now I have to because I bought Aikuma Senryo’s sukumo dye.

Research notes

The Japanese version of the Aikuma Senryo website has a lot more resources: https://www.aikuma.co.jp/html/page25.html. The recipe there relies on their proprietary reducing agent, “AZ Simple” (supposed a lot stronger than hydros): https://www.aikuma.co.jp/view/item/001001000030.

Their english website also has instructions, but I suspect they are incomplete/leave out key info (ie what temperature to maintain the vat?): https://aikuma-japan.com/blogs/the-history-of-japan-blue/how-to-reduce-sukumo.

This Dekel Dyes post seems to make the process seem simple enough: https://naturaldyestore.com/blogs/blog/the-sukumo-indigo-vat-a-time-honored-tradition-in-dyeing-aizome.

The vat needs to be maintained at a certain temperature (what temp?), and seedling heat mats or aquarium heaters are two continuous heating solutions that have been proposed.

Catharine Ellis has a detailed series of blog posts on fermentation vats, including one that is instructions on making a fermented indigo vat. I have not read them all: https://blog.ellistextiles.com/2025/05/.

This blog post was scary but informative: https://www.woodspirithandcraft.com/blue-notes/repost-making-japanese-sukumo-indigo-vats-for-north-house-unplugged-2025. Apparently the vats stink! How am I going to do this in my NYC apartment? This is the kit she referenced in the blog: watanabes.jp/en/collections/sukumo-aidate-kit.

There is also a Facebook thread discussing this: https://www.facebook.com/groups/indigodye/posts/1954159628455927/.