woad dyed samples

Two pictures of woad dyed samples from the workshop at Woad Inc last April. Following dyeing they were rinsed umpteen times in water with Ecover, with a final rinse in vinegar (as advised for indigo by Vivien Prideaux). The vinegar rinse seems to stop further dye washing off, somewhat magically to a non-chemist! They haven't yet been boiled to remove wax but being rinsed in hot as well as cold water most has already gone. When I have enough to justify boiling up the burco then they'll get boiled out.

Woad Inc's vat was already made. Alkalinity was raised to pH9 with soda crystals and Hydros added to remove oxygen. The vat was steaming away, at 55 deg C. I was concerned it was too warm and would make the wax melt. Some dye was taken out and cooled to 35 deg C in its new bowl. This was used for dyeing the four prima, in a series of dippings, as shown in the first picture.

This cotton had no initial scour: the samples went straight in the vat (after soaking in water). Each group dip lasted approximately a minute, then the samples hung to air for up to another minute. So the lightest piece had only one approx-minute dip, and the next darkest two dips etc, up to four. There seems little difference between third and fourth dips - I am putting this down to my bad approximate timings or alternatively, lax control over which piece went in or came out first. It was all rather rushed. However, the colour is nicely even and for what it was meant for, the test has worked well.

The six organic cottons plus prima (non-organic) as control had substantial scouring, based entirely on trying to make powerloom evenly absorbent. On this test I was successful, despite being over the top! I washed the cottons 'with agitation' in hot water with Ecover. Following a rinse they were left to soak in hot water again with Ecover over two nights. They then were well-rinsed individually, followed by a 10-hour soak collectively in water, powerloom soaking separately. And rinsed again before hanging to dry. Whilst most of the cottons didn't need this treatment, subjecting them to the same ordeal as powerloom was necessary for making comparisons after dyeing.

These seven text pieces, shown in the second picture, were dyed in the formally too-warm vat, which had cooled to 45 deg C, after a soak in water. They had one collective dip, for approximately 10 minutes (despite then having a timer, I managed to not set it properly, so still no accuracy over timing). Again, I was uncertain which went in first and which came out last, though I think I gave powerloom longer.

Sadly, all seven pieces have not dyed evenly, including the test prima. Ian at Woad Inc believes this is related to air (ie oxygen) somehow being introduced to the dye bath - such as clumsy insertion of cloth. This might explain why powerloom has dyed so badly in the past - if it has been unable to absorb water then air must be in the fabric instead thus introducing it to the dyebath? But it also could relate to clumsy handling in the dyebath - cloth touching other cloth. Or back to the scour... should I have used Ecover? Was the three days soak in water alone sufficient for powerloom, or something from the Ecover not quite rinsed out despite my best efforts? Was it because the samples were dipped for 10 minutes? Was it the higher temperature? Certainly there's a difference between treatment of the two primas to make one dye evenly and the other not. Of course I kick myself that I didn't dye the organics in the same vat as the prima four-dip-series. It would have rule the vat out straightaway. I welcome any suggestions those more experienced in indigo dyeing can give...

Also worth commenting on is that the intensity of colour of the 10-minute dip prima is roughly the same as the twice-dipped-for-a-minute-each-time prima. Is that temperature-related, time-related, dip number-related or scour-related?

Memories from indigo dyeing with Abi Evans (outdoors) is that cotton was dyed cooler than animal fibres. With Vivien Prideaux and Isabella Whitworth (see here and here) their vats were blanket-wrapped but otherwise room temperature (though looking back through notes I find conflicting advice). But perhaps woad-sourced indigo acts differently, does require more heat? Although chemically the same as indigo-sourced indigo there may well be other things 'human expertise' doesn't understand about it (in the way that DNA was not mappable a decade or so ago).

Well, the answer is to get my own vat set up and find out! I haven't been able to yet, due to getting work done on the house, the tax return, and sowing of woad seeds that friend Helen will be growing for me. Frustrated that I can't get on with dyeing due to 'other stuff' I also am borecd of doing sample pieces only... it's also time to start developing designs appropriate for blue-chromism.