Dyeing Wool with Birch and Plum Tree Leaves using Alum Mordant at Various Concentrations

Not long ago, I accidentally mordanted some Shetland wool yarn using 20% of the weight of the wool in alum crystals, instead of my usual 10%. I thought the amount of colour the yarn picked up from a dye bath of birch tree leaves looked far more impressive than the colour on a smaller skein of the same yarn that had been dyed in the same bath after being mordanted with 10% alum. 

Over a cup of tea in the garden, my companion, Elinor Gotland, quite agreed.
"The little skein looks crap compared to the big one with more mordant. Looks like you've been spoiling the ship for a ha'porth of tar, Beaut. Speaking of ha'porths, how much does alum actually cost?"
"Well, very little actually. I paid about £12 for a kilogram, so even if I didn't reuse the solution, the difference between using 10g or 20g of alum to mordant 100g of wool would be 12 pence. I'm not so fussed about the money, so much as the environmental cost of using more."
"Oh, for heaven's sake, aluminium is the most abundant metal on earth and you're always harping on about how you exhaust your mordant solutions by reusing them three times. Do yourself a favour and get the best out of those plant dye baths you spend half your life brewing up. Making mouldy colours is a waste of all the natural gas you burn, simmering dye pots for hours on end."
"Hmmm. Maybe you've got a point, Elinor. I've read older dye recipes where higher percentages of alum seem to have been standard practice. Along with Glauber's Salts and a whole range of other stuff you don't see in the chemists' anymore. Perhaps the old girls had the right idea all along."

My accidental 20% alum mordant bath included some 50g skeins of Drops Alaska aran wool yarn. I mordanted a couple more skeins with 15% alum and 10% alum and then collected another 150g birch tree leaves while out walking the dog. After simmering the leaves for an hour, I added an equal weight of yarn and half a teaspoon of soda ash to bring the pH just above neutral, simmered the wool in the pot for an hour and left it to soak overnight.

Once the yarn had dried, there wasn't much difference between the three skeins. They were all more yellow and less green than the previous birch leaf dye, which may be because the leaves are no longer so very newly grown. The skeins were tagged, so I knew the one on the left of this picture was mordanted with 10% alum and could see it was only very marginally yellower in tone and slightly paler than the one on the right, which had been mordanted with 20% alum. This made it clear that I hadn't managed to replicate the conditions which produced the contrast between the original 20% versus 10% mordanted skeins. Above and beyond that, it made no sense to me that the skein in the middle, which had been mordanted with 15% alum, looked paler than either of the others.

Obviously, first thing to do was to repeat the test. No flowers are anywhere near blooming in the dye garden, but the plum trees espaliered against the wall needed their tips soft pruned this week. I used to get yellow dyes from the leaves of the apple trees that grew there before, so this seemed a good opportunity to test the dye potential of my plum tree leaves as well as repeating the alum mordant assessment.

150g fresh plum tree leaves were simmered in water for an hour. They released no perceptible colour into the dye bath and its pH tested as mildly acidic. I put three skeins of yarn into the clear fluid, although I only had 25g mordanted with 10% alum, and simmered them for an hour. Next morning, they looked pale yellowish green. When I rinsed them in plain water the yellow grew stronger as the acidic dye bath was washed out, so I gave them a final soak with half a teaspoon of dissolved soda ash. The alkali turned them a proper lemon, paler and sharper than the colour from birch leaves.

No two ways about it, the mordant results were essentially the same, only more pronounced. The 10% skein on the left of the picture is only marginally paler than the 20% skein on the right, while the 15% skein in the middle is paler than either of them.

"From the looks of that wool, you might as well carry on mordanting with 10% alum, Beaut. Don't bother increasing to 20%, save your 12p and spend it on a teabag." My companion gazed sorrowfully into her empty teacup. "I know it's wildly extravagant of me to expect a second cup of tea to have any colour in it."
"A second cup? Your teapot must hold the Welsh record for continuous use. It doesn't go cold all day."
The unsatisfactory tea concentration provided by Elinor's reused teabag did set me thinking. Does reusing an alum mordant bath really have just as good an effect as the first use? Could that original small pale skein have resulted from mordanting the wool in a reused alum bath? On reflection, I remembered that the 15% alum skeins of wool were mordanted cold, whereas both the 20% and the 10% alum skeins were mordanted by heating. These days, I often mordant wool without heat. It does seem to work, but I've never directly compared the dye results after mordanting wool by simmering in alum for an hour against the dye results on wool mordanted by soaking in a cold alum solution for 24 hours.  Maybe cold mordanting is why the 15% skeins came out so pale. Maybe in the original birch leaf dye bath, the little 10% alum skein was mordanted cold in a reused bath of alum.

No good speculating, I think I am going to need to do another trial to try to get clear on this point before the dye garden comes into flower. Still a few weeks to go yet.

Hammered Leaf Prints Made Fast with Iron Solution

Every May when the trees come into leaf, I find myself full of enthusiasm for their loveliness and inclined to start collecting some for hammer printing. Then I work away on a piece of cloth and soon remember hammering is a noisy business that rapidly grows dull and find I've chosen the soft, squashy kinds of leaves which get mashed into the fabric or dryer ones that barely leave a mark, no matter how I thump them. A lot of trial and error gets repeated every year for transient rewards, having found from past experience that the pretty fresh green hammer leaf prints will fade to pale beige within a few months of exposure to light. 

This year, I was encouraged to experiment again after checking my friend's curtains. Last year, I hammer printed leaf borders for them on mordanted fabric, then dyed the fabric in a bath of meadowsweet flowers with added iron, which turned the prints into brown silhouettes. Rather to my surprise, they haven't faded despite the sun shining through them all year, the curtains look much the same as when we hung them up last May. It seems to me that the leaf juices must have been able to pick up and concentrate the iron that was in the dye bath, as I know iron is a particularly lightfast mordant for plant dyes. This year's experiment was intended to find out whether it is necessary to premordant the cotton fabric in order to make iron hammerprints permanent.

First I mordanted one piece of cotton curtain fabric by simmering it for an hour in a solution of aluminium acetate at 5% the weight of the fabric. Then I made a dye bath by simmering 100g of silver birch leaves in water with a teaspoon of soda ash to increase the pH. Next, I collected leaves and wedged a board on a garden wall to provide a solid surface for hammering.

Using an old shirt to lay over the leaves, which were laid reverse side down on my curtain fabric, I thumped away until the juices had soaked through the shirt showing a complete leaf shape, lifted away the shirt then peeled off the leaves. After that, I did much the same to two more pieces of the same fabric which hadn't been mordanted.

One of the unmordanted pieces was just heated in water with a splash of dissolved iron. The other went into the birch leaf dye bath together with the mordanted piece and a slug of dissolved iron.

And here is how they turned out. On the left, the alum premordanted fabric has taken up the birch leaf dye with iron as a khakhi background colour and the leaf hammer prints have taken up both the modified dye and extra iron and gone brown. In the middle, the unmordanted cloth that went into the dye bath has picked up a tinge of background colour while the prints have gone brown. Finally on the unmordanted cloth that was heated in iron and water only, you can see the leaf juices in the hammer prints have taken up iron from the water to make grey silhouettes of variable darkness, presumably according to their affinity for iron.

Japanese Acer leaves make a pink fresh print with no apparent colour along their veins, yet the juice in the veins must picking up more iron, as the veins come up much darker than the rest of the leaf.

In future, I think I shall experiment more using unmordanted cloth with just an iron and water bath. The leaf prints go black within ten minutes of heating and you can rinse the cloth straightaway, getting rid of most of the residual iron on the fabric without washing out the leaf shape. Quick and easy method for making rather a striking contrast print. Might be nice to put a single leaf silhouette on a shirt. Or cover up a stain on the front.

A Trial of Birch Leaf Dye

My companion, Elinor Gotland, watched me empty out a pocket stuffed with birch leaves.
"I suppose you'll be boiling that lot up and stinking out the kitchen again."
"Simmering, Elinor, not boiling. I've no idea if birch leaf dye will smell, the books never say anything about that. And yes, the dog and I had a lovely woodland walk, thanks for asking."
"Mmmm, no sooner have the trees sprouted a few leaves than you go pulling them all off."
"I only stripped a twig from each silver birch I passed. Just going to check how much I've got."
"Oh, you're not weighing those leaves in the kitchen scales, are you? They might be covered in bird poo or anything."
"Oh hush, I'll give the dish a wash. Smile, why don't you, this is the beginning of an exciting new dye experiment."
"Not if you're a birch tree, it's not."

My fresh birch leaves weighed just over 100g. Ignoring Elinor's grouchy temper, I added water to the pot, simmered them for an hour and left them to cool. Jenny Dean's book Wild Colour said birch leaves would dye an equal weight of fibre which had been mordanted in advance, so I planned to add 100g of premordanted wool.

Three 25g skeins of Shetland wool yarn were already prepared, on the left, one mordanted with 10% alum, in the middle, one mordanted with 2% iron and on the right, one mordanted with 2% copper solution.  To take another look at the difference between using iron and copper either as mordants or as modifiers after dyeing alum mordanted yarn, I wanted a fourth 25g skein, so I put another Shetland one in with some other wool yarn I happened to be mordanting in alum.

A sample of the birch leaf dye bath looked pale yellow and tested mildly acidic with pH paper. Adding a little soda ash to a second sample deepened the colour, but I thought this time, I would not meddle with the pH of the whole bath, just leave it as it was and concentrate on the effects of metal mordants and modifiers.

All four skeins went into the dye pot with the leaves still in it, together with a small piece of unmordanted cotton and a piece of linen mordanted with aluminium acetate. They were simmered for nearly an hour and left to soak overnight.

Taking them out next day, at first I thought I had got my labelling mixed up. According to my routine, a skein with iron mordant gets a yellow plastic clip, a copper one has a white clip and the two alum mordanted skeins should have pink clips. After a pause for staring at the wool and thinking about recent results with daffodil, dandelion and ivy leaf dye baths, I decided the brownest colour was typical of iron premordant and had been correctly tagged and the warmer toned skein was likely to be copper as shown by its white tag. Which left the two pink clipped skeins, the first two on the left of this photo, both alum, but not identical, one being a much deeper and more vibrant yellow green than the other. 

Elinor had hidden herself in a shady spot, where I hoped a long, cold drink might be improving her mood.
"You won't dry that wool by breathing all over it, Beaut. And it won't do the colour any good to hang it in direct sun, it'll fade." That sheep is paranoid too much sunshine will bleach her fleece and still inclined to grouch at me. "What's a May Bank Holiday for, if not getting sunburned? Or awfully dehydrated?" Elinor clinked her ice cubes and bit into her cucumber slice. 
"Half a minute now, I'm trying to think."
"Ah, is that why you've gone all red in the face?"
"This second alum mordanted skein - I may have made a mistake with my calculations."
"Again, Beaut? It's no surprise you were in the Remedial Maths class at school."
"I think I mordanted it with 20% alum instead of 10% by weight. I put it in to mordant with some skeins of aran yarn and I reckon I must have done the whole lot wrong."

Before completing the planned trial, I took the paler skein of alum mordanted yarn and divided it into parts. One part was saved just as it was, representing my usual 10% alum mordant. In this photo, it is the little drab shein on top of the larger one, which I think had a 20% alum mordant.

Birch Leaf Dye on Alum, Iron and Copper Mordanted or Modified Wool and Aluminium Acetate Mordanted Linen

A short length of the 10% alum mordanted yarn was soaked in alkali solution, just to get an idea of what alkalinising a whole dye bath might do. It turned a brighter yellow, though not as saturated a shade as the 20% alum mordanted yarn (left). Another part of the 10% alum yarn was simmered for five minutes with a splash of iron water to modify it, turning a grey green, whereas the iron premordanted skein was much browner (centre). The final part of the 10% alum mordanted yarn was simmered with a splash of copper solution, turning it a green gold, less gingery than the copper premordanted skein (right).

Birch leaf dye has proved well worth a trial and it does look as though adding soda ash to alkalinise the bath would bring up the colour even more. As before, the effect of modifying alum mordanted yarn with iron and copper pleases me better than the effect of actually mordanting the yarn with iron or copper beforehand. After my probable miscalculation, it seems to me I should consider using a higher percentage of alum to mordant wool in future. The older dye books often specify using more mordant than modern authors recommend, could be the old girls knew more than they have been credited with. Hey ho, I already have some skeins which I think were accidentally mordanted at 20% by weight, they were Drops Alaska on sale at cut price from Wool Warehouse, so it won't cost a bomb to buy some more and do a few more experiments. And there are masses of birch leaves and far more to come.

A Trial of Ivy Leaf Dye

Allowing the front garden to grow wild looked delightful earlier this Spring, a succession of bulbs bloomed in the lawn to the admiration of at least some of my neighbours. Now things are getting that bit too shaggy, crossing the line between naturalised and neglected. Ivy has grown over the wall and nobody appreciates walking into a wet slap of leaves. After I cut back the worst, it occurred to me that I had read somewhere you can make dye from ivy leaves. Taking a tea break, I found a page all about ivy in Jenny Dean's book, Wild Colours. Jenny writes that ivy leaves and berries will dye an equal weight of material and are best suited to animal fibres.

There were few berries left on the pruned branches, though easily enough leaves to fill my dye pot. They weighed about 300g. Adding water, I put the pot on the stove to simmer and went looking for some test fibres to soak ready for dyeing. Lifting the lid an hour or so later, the leaves had softened and the rising steam had a tang of rhubarb about it, so something was being extracted, although the water in the pot had no apparent colour at all.

Testing a sample with pH indicator paper showed the ivy had at least made the clear fluid acidic. Adding dissolved soda ash to another sample worked like magic, a lucent yellow green instantly appeared in the jar. A teaspoonful of soda ash brought the pH of the dye pot up to neutral, green colour appeared and convinced me there was dye in there, so I added my trial fibres in with the ivy leaves and turned the heat back on. Giving the pot a stir ten minutes later, the green glow in the water had all disappeared again and the fibres hadn't taken on any colour at all. That rhubarb smell in the steam must mean acid release, because indicator paper showed the pH had already dropped back down to acid. I added another teaspoon of soda ash, completed the hour of simmering and left the pot overnight.

Next morning, the fibres had gone green and the dye bath fluid looked brown, though when I retested it, once again, its pH had become acidic. I suspect that my two teaspoonsfuls of soda ash provided far too little alkali to counterbalance the acidity from stewed ivy leaves and that my attempt to alkanise the bath had had little effect on the overall ivy dye process.

Here is how the fibres looked straight from the dye bath - from the left, two skeins of alum mordanted wool yarn, next, one iron premordanted skein and one copper premordanted skein and the piece of linen mordanted with alum acetate. The unmordanted cotton fabric had not taken up significant colour. I divided one of the alum mordanted skeins into two smaller skeins and one short length. The short length was soaked for 20 minutes in an alkali solution. One small skein was briefly reheated with an iron solution to modify its colour and the other was modified with a little copper solution. 

Here is the final result of ivy leaf dye using twice as much weight of leaves as wool. On the left, alum premordanted skein with a bit on top that was modified with alkali after dyeing - far from improving the colour, it diminished it. Bottom row, a brownish version on the iron premordanted wool and a good green from the copper premordant, then just to mix things up, the two small skeins on top show a bright green from alum premordant and copper modifier and a dull green from alum mordant and iron modifier.

Ivy leaves are plentiful, more are coming over the wall already, it's good to know I can make green dye all year round. In future, I shall not be adding any soda ash, just trusting that the colour will develop once the wool is in with the softened leaves. I would certainly consider copper a useful premordant. As a modifier, copper took effect much more quickly than usual - I am only just realising that to modify dyes well with copper, you really need to add it in an acidic bath.

Here's a green wool heart for the Green Man as he dies and lives in the force of Spring.