The hills across Shetland turn purple and pink during July and August as the heather flowers. The flowering tips are used for dyeing the wool. Collecting some tips is a delightful experience on a summers day in the dye garden with the sound of the Laverick, (skylark), singing high above.
The freshly cut tips need to be soaked overnight in soft water. The next day it is time to prepare the dye vat. The water and heather needs to be heated slowly to a simmer, then this temperature held for about 45 minutes. The liquid will slowly change colour and the dye vat can be left to cool.
The next stage is adding the wool to the dye liquor.
Shetland sheep are small hardy animals. The wool is soft and full of lanolin making the fleece water repellent. Hill sheep are also living in peat conditions so the fleece is often dirty. It is essential to clean the fleece thoroughly before attempting to dye the wool. Soak it in hand warm soapy water overnight, rinsing and repeating as many times as needed until the fleece is clean. Then a mordant needs to be used to enable the fleece to absorb the dye pigment.
To see how and why a mordant is used click the link
The vat can be strained and just the liquor used or the fibre can be added whilst the Heather tips are still in the pot. The latter will give a deeper shade, the tips will need picking out afterwards!
Either way once the fibre is in the vat heat to a gentle simmer and hold for about 45 minutes. Leave to cool, preferably overnight for good colour. Then remove the fibre and rinse well, wash with handwash then rinse again.
Flowers from Bell Heather gave shades of yellow when the wool was mordanted with Alum.
When an after mordant of iron, made by soaking an iron nail in white vinegar for several weeks, was added the yellow shifted to greens.