Pigment-making at Unnaryd’s Bonads Museum in Sweden, July 2013

This little museum is situated in Unnaryd, a village of 759 inhabitants in Småland, Sweden. It has a wonderful collection of ‘Bonader’, paintings made by the local peasant farmers in the 18th and 19th century. Every summer, Sue Prince, an English organic farmer who paints in the tradition of the Swedish ‘Bonad’ painting does a workshop in Bonad painting. This summer, in tandem with my exhibition at Hallands Konstmuseum, I was invited to contribute a workshop in pigment-making from wildflowers and plants to the week of Bonads painting.

One of the most common and important pigments used by the Swedish Peasant Painters was the blue pigment from woad (Isatis tinctoria). The plant would have been cultivated in Sweden. I sent some woad seeds to Gunilla and Sören Kabell, the guardians of the museum, earlier in the spring so that the plants would be ready for harvest at the workshop this summer.

 
The rosettes of woad tenderly cultivated by Gunilla Kabell.

The rosettes of woad tenderly cultivated by Gunilla Kabell.

 

The woad plant is a brassica, in the mustard and cabbage family. It is biannual, flowering only in the second year. It is during the first year, when it doesn’t flower that one harvests the leaves for extracting the indigo blue pigment.

Steeping the torn woad leaves in hot water.

Steeping the torn woad leaves in hot water.

First we tore up the freshly harvest woad leaves, then plunged them into water at 80c. We kept them at 80c for 10 minutes, then we plunged the whole pan of leaves into a tub of ice cold water. The aim is to cool the bath of leaves down to 55c within five minutes, according to a recipe by Jenny Dean.

Cooling down the woad bath with ice packs.

Cooling down the woad bath with ice packs.

Then we strained off the leaves from the bath, taking care to squeeze out all the leaves.

Everyone joins in squeezing out the leaves.

Everyone joins in squeezing out the leaves.

At this point the water has a brownish colour – no blue is visible as yet. To reveal the magic of woad we must add some alkali to bring the ph to around 9. One can use soda ash, lime water or stale urine. We had potash to hand that we were going to use later on in the workshop for other pigments, so that is what we used. We carefully dissolved some in warm water and added it to the brown water, testing with ph paper until we reached the correct level. At this point the bath takes on a greener colour, but still no blue. The next stage was to whisk it…

Whisking oxygen into the woad bath.

Whisking oxygen into the woad bath.

The indigo contained within woad only becomes blue when it is in contact with oxygen. As we introduce oxygen into the woad bath by whisking, we start to see blue colour in the froth. When indigo is oxygenated, it also becomes insoluble in water. We pour the blue-containing liquid into jars and let the blue settle out on the bottom.

 
Jars of dark, indigo-containing liquid.

Jars of dark, indigo-containing liquid.

 

When the blue had settled out on the bottom, we syphoned off the brown brackish liquid that lay over it. At first it is very hard to see the deposit of blue pigment through the dark water. We didn’t want to loose any of the precious blue so we left an cm or so of the brown liquid over the blue deposit on the bottom.

 
Syphoning the brackish brown water from the blue indigo pigment.

Syphoning the brackish brown water from the blue indigo pigment.

 

We poured fresh clean water over the blue pigment and allowed it to settle out again. We repeated the syphoning and fresh water process until the water above the deposit of pigment was clear.

A close up of the deposit of indigo from woad on the bottom of the jar.

A close up of the deposit of indigo from woad on the bottom of the jar.

When the water was clear, we were ready to strain the pigment. The pigment particles are very small, so we used two layers of tightly woven cotton cloth.

Now that we had a blue, we needed yellows and reds to create a complete palette. For this we used a ‘laking process’, a variety of wildflowers to see what colours we could get.

Rosebay willowherb and goldenrod.

Rosebay willowherb and goldenrod.

For yellows, amongst others, we tried birch leaves, rosebay willowherb (Chamerion angustifolium), goldenrod (Solidago canadensis), and yarrow (Achillea millefolium). Birch leaves have been found to be one of the plants used by the bonads painters to make pigment. Ingalill Nyström completed her phd in autumn 2012, analysing the materials and technique used by the Southern Swedish bonads painters. It is the first time these works have undergone technical analysis and Ingalill was invited to come and give a fascinating talk about her findings at the museum on the first day of the week of workshops at Unnaryd.

Birches were important healing trees for the Swedish peasants, not only could they absorb toothache, but they could also absorb any emotional pain if you told the tree about your worries or sadness. Yarrow was also a medicinal herb, used to stem bleeding. Rosebay willowherb was given to cows to increase their milk yields – one of its many names in Swedish is ‘mjölkört’ (milk herb). The particular goldenrod pictured is Canadian goldenrod, which was grown in gardens and has now gone wild and is very common in Sweden. There are also some native goldenrods (Solidago virgaurea, S. alpestris) which can form hybrids with the native goldenrod where they grow together, as they do round Unnaryd. Goldenrod was used as a strengthening tonic and to treat kidney problems.

For reds we used madder roots and surprise webcap mushrooms for purples. Madder (Rubia tinctoria) would have been cultivated in Sweden, but there are also related native plants which contain the same red dyestuff in the roots. They are the bedstraws (Galium), such as lady’s bedstraw (Galium verum) and Northern bedstraw (Galium boreale). The roots are best kept for a year before use, so I brought some madder roots to the workshop, but I indicated the wild plants which are types of Galium.

Harvesting lady's bedstraw (Galium verum) roots for red.

Harvesting lady's bedstraw (Galium verum) roots for red.

These Lady’s bedstraw roots that I harvested will be used in a years time. It spreads through rhizomes so the best is to dig quite deep to find the larger, older roots that connect the various spreading clumps. I leave plenty of plants in each clump so that it is sustainable.

The process for making pigments from all of these plants uses the same ‘laking’ process which is distinct from the process of extracting indigo from woad. First the plant matter, the leaves, flowers or roots depending on the plant, is simmered in water with alum (potassium aluminium sulphate), ideally for a couple of hours to extract as much colour as possible. With the majority of plants it is best not to overheat, keeping it below boiling point at around 70c to 80c, as too much heat can destroy the beautiful colour.

Madder roots simmering with alum.

Madder roots simmering with alum.

When then drained the various plant matter from the dye baths. At this point we had beautifully coloured dye baths, but this is not suitable for painting. We need an insoluble pigment which we can grind up in egg or oil. The ‘laking’ process is what makes an insoluble pigment. We did this by adding potash (potassium carbonate) to the dye bath. The proportions are about one part potash to two and a half parts alum, however, we used ph papers to make sure the we had poured the correct about of potash in. Alum is acidic, and potash is alkali so they neutralise each other. The results are quite dramatic:

 
The fizzing reaction of potash and alum.

The fizzing reaction of potash and alum.

 

The potash and alum react with each other, giving off carbon dioxide (hence all the foam), and forming a precipitate which has been coloured by the plant dyes which settles on the bottom of the bucket. Once all the fizzing foam had subsided after a few hours, we strained the pigment through old pillow cases which we hung in trees. We rinsed the pigment in fresh warm water to get rid of any excess alum and strained through the pillow cases again. Then laid out the wet pigment on newspapers to dry. We got a full range of stunning pigments:

Birch leaf pigment

Birch leaf pigment

Goldenrod pigment

Goldenrod pigment

 
Woad pigment with a woad plant behind to the right.

Woad pigment with a woad plant behind to the right.

 
 
Purple from surprise webcaps (Cortinarius semisanguineus) and red from madder roots (Rubia tinctoria).

Purple from surprise webcaps (Cortinarius semisanguineus) and red from madder roots (Rubia tinctoria).