More from the one-year natural dyeing course at Ditchling Museum (3)

At this session we concentrated on dyeing with alkanet root (Alkanna tinctoria), cutch (Acacia catechu) and rhubarb root (Rheum spp.) All these dyes are substantive, so no mordant is necessary. However, we added an alum-mordanted wool sample to the alkanet dye bath, as this should give a lavender shade. As usual, we tested the dyes on wool, silk, cotton and linen fibres and applied modifiers after dyeing. As modifiers we used clear vinegar (acidic), soda ash (alkaline), copper water and iron water.

To simplify the process, we tied the alkanet root and the rhubarb root into muslin bags before adding the water to the dye pots. This means the dye bag can be removed from the dye pot once the colour has been extracted, so there is no need to strain off the dye liquid. The dyestuff in the bag can usually be simmered again for a further dye bath.

With the exception of cutch, the dye baths were prepared by simmering the dyestuff for about 40 minutes to extract the dye colour. Cutch is usually supplied as an extract in powder form, so it needs only to be carefully mixed with warm water and then stirred into the dye bath. It is important to make sure the cutch has dissolved completely, otherwise any loose particles will cause stains and spots on the fibres.

 

Alkanet root before being chopped (Photo by Jennifer Nightingale)

       

Light and dark cutch blocks before being made into powder (Photos by Jennifer Nightingale)

Cutch dye solution

Alkanet root dye solution

Rhubarb root dye solution

CUTCH SAMPLES 

Left: see below Centre: from top – linen, cotton, silk Right: paper samples

From left: no modifier, + acid, + alkali, + copper, + iron (photos by Ross Belton)

Alkanet root produces a less than pleasant aroma when simmered and without a mordant usually gives colours in the grey/green/brown range. The purple dye is best extracted by soaking the root in rubbing alcohol or vodka for several days or even weeks before simmering it for dyeing. However, the dyeing process produces unpleasant fumes and great care must be taken to keep the solution away from naked flames, as it could easily catch fire. And it cannot always be guaranteed to produce purples. (See my earlier post on Alkanet Root for more details.) Unfortunately, using an alum mordant did not guarantee purple either this time, so once again my experiments with alkanet had limited success.

In Japan, the roots of the purple gromwell plant, Lithospermum erythrorhizon, which look very like the roots of Alkanna tinctoria, are used and tend to more reliably produce lavender and purple shades.

ALKANET ROOT SAMPLES

Left: as above for cutch Centre: from top – linen, cotton, silk Right: paper sample

From left: as above for cutch (Photos by Ross Belton)

Rhubarb root is always interesting to use, as it reacts so positively to the modifiers and a wide range of shades can be achieved. And as an added bonus it doesn’t smell unpleasant either.

RHUBARB ROOT SAMPLES

Left: paper samples Centre: from top – linen, cotton, silk Right: as for cutch

From left: as above for cutch (Photos by Ross Belton)

Part of each session is devoted to assembling the dried samples from the previous month onto sample cards and it is always a pleasure to see the results from each session.

The tasks of mordanting and preparing samples is also ongoing and at this session we treated animal fibres with a rhubarb leaf base and also mordanted more fibres with tannin. We will be using these samples at a later date.

 

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