Friday, September 11, 2015

blue pigment from woad

Woad (Isatis tinctoria) seeds were purchased from Sand Mountain Herbs.  Having read that this plant is a heavy feeder, classified as an invasive weed in certain states and that the water shed off the leaves may be a germination inhibitor for other seeds, I planted the seeds in shallow drills in two giant plastic plant pots on a gravel covered patio separated from any other gardens by a paved driveway.



Economically frugal as always I planted the seeds in the soil that was on sale, Miracle-Gro.  And fertilized it every month with liquid miracle grow.  Next year, in hopes to yield more blue I will plant the seeds in an organic, rich mix, fertilize organically and harvest the leaves earlier.

Extracted from the leaves, indican and isatan B can be converted into indigo!
Jenny Dean's Wild Color explains four methods to dye using a woad vat.  I decided for the first year I would try Method 1. It involves washing soda and sodium hydrosulfite (Sodium dithionite/Na2S2O4).  Had I known how bad the hydrosulfite smelled I would not have ordered any.  Hindsight is 20/20, right?  It came in two layers of plastic and two of cardboard too.  Not sure where to store it, it's wrapped in four layers of plastic in plastic storage drawers.

I soaked the fabrics overnight in a gallon of bottled water.  The water turned a little yellow/brown and tested between pH 5 and 6.  Possibly because I didn't clean it enough.  Cleaning the fabrics before dyeing is called scouring.  Next time the fibers will be scoured more thoroughly.  I've read online that uneven dying is a common problem for new dyers and perhaps why my colors came out unevenly.  The morning I harvested the woad leaves there was more plant material than I thought so I threw more fiber and fabric in to soak.

Harvested the woad leaves from the plants in the two pots.  Looks like there were only about seven plants but they yielded a surprising 428g of leaves.  I cut them up using scissors and poured nearly boiling (190F) water over them.


I let them steep for the recommended hour and got my sherry colored liquid!


Pouring the whole concoction through a strainer into a bucket, I reserved the leaves for a second dye bath.

Letting the dye vat cool to 120F seemed to take for ever!  Once it had, I sprinkled about two teaspoons of washing soda to turn it to the essential "greeny-brown" color. and introduced air with an electric mixer.  The bubbles changed from clear to blue quite quickly.  There was not an abundance of bubbles like I hoped but what bubbles there were I skimmed off and ladled in to a glass bowl.

In retrospect I should have saved some of this liquid and let the blue settle out to try to make my blue paint.

Daniel V. Thompson talks about the flower on pg138 of The Materials and Techniques of Medieval Painting.  "In the course of dying a scum collects on the surface of the vat, and this was called in Latin the spuma or flos indici, and in English, "florey", or the flower of woad.  This foam or flower was skimmed off and dried and used, either alone or in more or less elaborate compounds, under the name of indigo in the Middle Ages.

There was very little foam on the surface.  The foam dried quickly and was only enough to paint a tiny bit.  I think the leaves were harvested too late and the dyeing potential had decreased as we can see by the weak results on the fibers.


Almost everything on the linen got washed away when I rinsed and washed the fiber and fabric as recommended.  The cotton produced a pretty blue cloud effect.  The unevenness on those pieces can be attributed to incomplete scouring.  The wool wasn't scoured and soaked properly and picked up dye patchily so there's variegated wool yarn.  The silk was dipped twice and gave me the most even result.  The end shade of that piece was s soft baby blue.

Next time I'll dye at the peak plant health with hopefully more plant material and definitely with more effectively scoured fabric and wool.







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