After two spectacular failures with traditional fermentation vats, I tried a modern indigo vat following the thiourea dioxide/lye recipe in Liles.
2 oz natural lump indigo, ground.
thiourea dioxide (aka Spectralite)
lye (Red Devil Sodium Hydroxide)
Grind indigo into talc-fine powder. Add 1/2 cup water. this is the indigo paste.
In a 1/2 gallon plastic milk jug filled with warm water, mix 1 tsp lye, 4 tsp of the indigo paste, and 1 tsp thiourea dioxide.
This reduces quickly to a pale yellow green, covered with a purple coppery film. There was unreduced indigo at the bottom, as I had not ground it all fine enough.
Fill a 15 gal plastic tub with lukewarm water. Add 1/4 a tsp lye and 1 tsp thiourea dioxide. Stir. Wait 20 minutes. (This keeps the indigo from reoxydizing when it enters the dye vat.)
Add the contents of the stock bottle, but not the grounds at the bottom. Wait until the vat is yellow-green. There's small mucousy cloudy particles floating throughout it.is this indigo, or what?
Add wetted wool fabric. After 20 mins, the fabric is a light blue. After 1 hour in the vat, the fabric is a medium blue. 3 20-minute dips is only slightly darker than 1 hour-long dip.
After multiple dips of a pound of wool, I reduced 2 tsp more indigo paste and added that to the vat, and added some yellow & red wool. I got respectable medium greens & bright purples, but nothing dark.
There was still some indigo left in the vat, but I had to let the bath sit a week, before I had time to do another dye the next weekend. All of the indigo oxidized in the 15 gallon vat over the course of the week. So I strapped a heating pad to the vat, brought five gallons of the vat to 150 degrees and poured it back in. That warmed it up, and the heating pad on high kept it to blood temperature even in 40 degree weather.
I put in 2 tsp of lye and 2 tsp of spectralite, stirred, and left it for 40 minutes. It turned yellow-green again, though not as yellow as the first time, and not as cloudy.
I dipped the linen again, and a large piece of yellow weld-dyed wool, and a piece of bright coral madder/brazil wool. Left it for half an hour, took it out to air; left it in another 45 mins, took it out to air, left it in 20 minutes, took it out to air. Also dyed some linen thread. Didn't get as deep a green on the weld after an hour, and hardly any purple shading on the red. The dye vat was apparently exhausted.
So I took the rest of the 2 oz. of indigo paste, added it to a half-gallon jar with 1 tsp thiourea dioxide and 1 tsp lye, and waited for it to reduce. It didn.t seem to reduce well, so I added another tsp of thiourea and waited another hour. It stayed a darkish green, but I decided to add it to the vat anyway.
I added another tsp lye and 1 tsp thiourea dioxide to the vat, waited 15 minutes, and poured in the stock solution by sticking the jar underwater and tilting it into the vat. I stirred and waited an hour. Once again the vat got cloudy and green, though never as yellow as it got the first time around. I put in some fabric.
I got some really lovely dark blues and greens this time, especially on the wool. If I.d had time to do multiple dips I.d have been able to get near-blacks, but it was freezing outside and I had to cut my experiment short.
#1: Spectralite ROCKS!
#2. It was hard to get a decent very dark blue with the amounts specified in Liles. I don't think I had enough indigo in the mix for the size of my vat.
The brazilwood red turned a BRILLIANT purple! Beautiful. the 20-min dip was brighter than the 40-min dip. The pink turned a duller medium purple. The very bright weld turned an acid green. The duller weld (that had been rinsed in a lye bath after the weld dye) turned a very pretty medium grass green after an hour in the vat.
I dyed 2 yards of linen, and found that linen fabric wants to float more than wool, even after soaking in water for an hour beforehand. Any spots which are left above the water turn darker blue.
1: various shades of blue on wool. Multiple dips in the same vat.
2: greens on bright weld.
3: greens on dull weld.
4: purples on brazil pink.
5: purples on brazil red. Linen, various shades.