Thursday, May 1, 2014

The dyeing begins! First indigo vat

I thought I'd need another week to get ready, but when I saw the forecast for a quick stretch of warm weather, I ramped up my schedule.  On Tuesday, I ran out and bought a stainless steel pot (capacity just shy of 16 quarts) along with other last-minute supplies, and on Wednesday, I made my first dye bath:

Note the yellow-green color of the dye bath beneath the blue at the top: reduced indigo.
Indigo requires an alkaline solution, as well as a reducing agent, in order to dissolve, and it needs to be in a chemically reduced state in order to bind to fibers.  When reduced, it appears yellow-green, and it turns blue when exposed to air.  There are a number of different ways to prepare an indigo vat, including various chemical methods, as well as techniques that use natural substances, such as fruit, as reducing agents.  The method I learned last fall uses lye for alkalinity, and thiourea dioxide (thiox) as a reducing agent.  It's a two-part process that requires making a concentrated stock solution, and then adding the stock solution to a larger bath.

Here's my stock solution, prior to pouring it into the vat:

Note the yellow-green color: evidence of indigo in a reduced state.
Despite my best efforts to follow the instructions and notes from October's workshop on how to mix the vat, I made all manner of mistakes.  I don't think my indigo was thoroughly wetted when I worked on making it into a paste.  Then I had trouble getting the thiourea dioxide to dissolve, so I poured it into the lye solution before pouring the lye + thiox into the indigo paste, rather than pouring the lye solution into the indigo, followed by the thiox solution.  I forgot to add Synthrapol to the dye vat before pouring the stock solution in, and then I also managed to drop the jar of stock solution into the dye vat (so much for avoiding splashes and doing everything gently in order to avoid oxidation).  I also didn't bother skimming off the "flower" (a.k.a. blue scum) floating on the surface of the dye bath, which is not a step I will skip in the future.

Even so, the dye vat worked reasonably well, although I did have some problems.  I tried dyeing solid fabrics, along with several itajime (clamp resist) samples, a fat quarter of nui shibori (stitched shibori), and one pleated and pole-wrapped piece.  I will start showing pictures of fabric in my next posting.

For now, here's part of the clean-up at the end of the day:

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