Ginkgo Leaves for Dyeing and Contact Printing

"The end is nigh, Beaut." 
My companion, Elinor Gotland, addressed this apocalyptic comment to my backside, as I bent to gather up yet more leaves.
"It's too late for me to start repenting. I'm too old. Must be nearly twenty years since I planted this ginkgo tree."
"The end of Autumn is nigh, not the end of the world. Or you, you mad old trout."

I straightened my back and sighed.
"Actually, I am repenting, Elinor, regretting my lack of forward planning. I never thought about how tall that ginkgo seed would grow, in another twenty years this could be an enormous tree. I should have pruned off at least a branch or two before the new greenhouse was put up."
"Oh, don't be so gloomy. I meant the end of falling leaves is nigh. The end of sweeping them up."
"And the end of my autumn leaf contact printing. There were so many more experiments I meant to do. Winter is nearly here, why didn't I use more of these leaves while I had the chance?"

"Oh, for goodness sake, do be a bit more positive." Elinor shinned up the tree, stripped a branch clean, filled a small pan with the leaves and plonked it in front of me. "Look, there's plenty in there to make one of your smelly little dye baths."

Which wasn't quite the experiment I'd been thinking of, but wasn't such a bad idea.

Rolled and tied in a bundle of mordanted cloth, whether simmered in a dye bath or steamed, I have found that ginkgo leaves don't release enough dye to make a visible contact print. 
However, when they are laid on fabric that has already been plant dyed, then covered with an iron blanket and rolled up, after steaming the bundle, ginkgo leaves do seem to reduce the colour of the original dye on the fabric underneath. This photo shows how pale a shape they left on Dyers Chamomile dyed, alum mordanted silk. Some of the other leaves have also reduced the yellow background and a few kinds have added their own dye colour, but the net result is that the ginkgo leaf silhouettes are the most strikingly pale.

One of the experiments I did get round to was trying a copper blanket. Rather than soaking a strip of cotton in dilute iron solution, I soaked one in a bowl of water with a splash of fluid from my jar of copper piping which has been soaking in a mix of water and vinegar. No idea how much copper was in that splash, enough to turn the water and the cotton fabric pale blue.

This silk had been dyed pink with silver birch bark, which turns a deeper, purple pink when modified with copper in the dye bath. I  laid my copper blanket over the ginkgo leaves and also some oak leaves, which had been dipped in iron solution, rolled all the fabric up with a layer of clingfilm and tied it firmly.

I hoped that after steaming the bundle for an hour or so, I would achieve a lovely deep pink where the blanket had pressed against the silk and a paler pink where the ginkgo leaves reduced its background colour. In practice, the ginkgo leaves worked as expected, but the copper blanket didn't really modify the birch bark dye half as strongly as copper in a dye bath would have done. I think the dark iron oak leaf prints look too heavy and clumsy on the pastel background and I must have dripped iron solution here and there and made unwanted grey marks. 
Good job, there's always overdyeing, because another experiment with an iron blanket on wool fabric didn't go well either.

I spread the dyed wool with a whole range of leaves and flowers and madder roots before steaming, but the result was a feeble shadow of the effects the same leaves have produced on silk. If you look at the bottom right corner, you'll see a ginkgo print which had a flower pressed underneath it. I have noticed before that these flowers print blue at neutral pH and turn purple after an acid rinse. Since this flower had printed purple, it was my guess that the ginkgo leaf had released a considerable amount of acid during the steaming phase. I've read people calling the process by which some leaves reduce the colour of a plant dyed fabric background as an 'exhaust'. Which does give an idea of the result, but doesn't explain how it happens. I suspect that 'exhaust' leaves are acidic and that they don't remove or destroy dye so much as modify it. Many flower dyes and bark dyes look much paler in acid conditions and strengthen if you add an alkali, like soda ash.

Meanwhile, back in the kitchen, the ginkgo leaves gave off a distinct tang as they were simmered in the dye pan for an hour. Once it was cool, I sieved out the leaves and poured a little of the fluid into three jam jars. I added white vinegar to the first, left the next just as it was and added some dissolved soda ash to the third. Testing with indicator paper showed that the pH of the original dye bath was naturally acidic, coming up at about pH5. Adding vinegar to increase the acidity made no apparent difference to its faint yellow colour, whereas adding soda ash turned the dye a much more powerful yellowy green.

The original weight of dry leaves had been 150g, I put 30g of alum mordanted wool yarn into the pan (a 5/1 plant/wof ratio), simmered it for an hour and the result was ... slightly beige yarn. So ginkgo does not work like ivy leaves, which give colour to wool despite making a pale and acidic dye bath. Thinking I'd take advantage of the acidic conditions to modify the yarn with copper solution. I added a small splash and warmed the dye bath again. There was still precious little colour on the wool until I added enough soda ash to the cooling bath to bring the pH up to neutral. Here's a picture of the finished skein of alum mordanted, copper modified, pH neutralised, ginkgo dyed wool yarn. On top is a length of wool I took out before modifying with copper. One end was soaked in the soda ash alkali jar, which made it bright yellow, the other end remains off white/beige.

In conclusion, I don't think I'd bother dyeing with ginkgo leaves per se. They needed so much alkali to bring up a strong yellow that the wool fibres felt harsh and damaged, and the copper modified khaki I got at neutral pH is not a colour I'm wildly excited by. Judging by the way it behaves, I'd guess the dye in the leaves has much in common with luteolin, which I can source from weld or a wide range of wild and cultivated flowers. The reason to be cheerful and not to regret having grown a ginkgo tree in my garden is the 'exhaust' effect of the acid released by the leaves during contact dyeing. And of course, the tree itself is a lovely sight. Soon to be minus a couple of branches.

My companion and I stood in the garden, sizing up the job.
"You can't regret planting a tree, Beaut."
"True enough, Elinor, I guess this one will outlive me."
"It could outlive your great, great, great grandchildren and then some. There are ginkgo trees in China said to be over 2,500 years old."

"Wow, that's amazing. Nice to think I really started something when I germinated that ginkgo seed. I'd better be careful not to harm it when I do this pruning."

"I reckon it will survive even your worst efforts, Beaut. Ginkgo trees are 'living fossils', they've been around for more than 270 million years and made it through major extinction events. Gone one better than the dinosaurs."
"Ooo. I shall name this one Betty, after Great Great Aunty Betty. I'm glad to have it here, growing old with me."
"You'll be even more pleased when you start to lose your marbles. Research says an extract from the leaves could help treat Altzheimer's. In the meantime, you could dose himself up on ginkgo tea and see if that lives up to its reputation." Elinor performed a short, but seductively suggestive fan dance with one of the leaves. 
"I think I'll just knit him something."