Dyeing can be described as part science, part alchemy. It is what imparts colour to a raw material, though the same dye may yield different colours. This depends on whether, for example, a yarn is wool, cotton, silk etc.
Dyeing of Exmoor Horn Wool
Exmoor Horn wool is dyed using synthetic rather than natural dyes. The advantages of this are that no toxic mordants are used. Also it is possible to obtain consistency of colour in a large batch of wool.
With natural dyes, unless the dye is substantive, e.g. walnut, it needs a fixative (mordant) to stick it to the wool. Some of these, such as copper sulphate or potassium dichromate, are toxic and pose disposal problems.
Natural dyes, though subtle, usually require large quantities of plant / insect material. Their pigment-giving qualities can vary with time and weather giving rise to a lack of consistency.
Dyeing with synthetics
Synthetic dyes are by-products of the pharmaceuticals industry. There are about 100 base dyes and an infinity of actual dyes. Any colour can be copied using a spectrometer. A computer can then calculate the percentage of each dye needed to make that colour, and the concentration required.
The colour may have many components, but the result will always be checked by human eye. A dye technician also checks what a dye looks like depending on the fabric, and under a variety of lighting conditions.
Dyeing absorption rate
Wool absorbs nearly all the dye in a dyebath, unlike cotton which only absorbs about 50%. You can see this below with a dark green thread emerging from an almost-clear dyebath.
Dyeing process
Exmoor Horn wool is usually dyed on 1kg parallel-sided cones (pic 2) rather than revolving skeins as in pic 4. The yarn has been wound onto perforated plastic cylinders. These are then stacked on a metal framework before being lowered into the vast dye vat. The base of which you see in pic 1.
The dye bath rises 1 degree C per minute up to a maximum of 80 degrees. Steam and or water enter at the base, with the water flow exerting a push-pull effect to ensure even colour dispersal.
When dyeing is complete, which does not take long, the wool is dried at a rate of half a tonne an hour.
Additions beyond the dyeing
In addition to the dye, a lubricant can be added to the bath if the yarn is going to be used in machine knitting, and our yarn is also waxed to reduce friction. If a yarn does not move smoothly through the needles of a knitting machine then variation in tension will result in damage to the machine, and breakages in the thread. Our DK handknit is not waxed since it is sent from the dyer to a specialist yarn finisher who steams, conditions and then balls it for us, using our own labels.
Dyeing to Exmoor colours
Exmoor Horn wool dyes replicate the colours of the Exmoor landscape: Heather Purple, Gorse Yellow, Fern Green, Earth Red, Dark Skies Blue and Natural.
More recently, we based our new pastel palette on the land and sea colours around Bossington, a tiny coastal village just east of Porlock: Bossington Pebble, Bossington Barley, Bossington Bracken, Bossington Sea Mist, Bossington Sea Green, and Hedgerow Pink.