Dyeing Purple-Grey with Blackberries — The Hedgerow Dye of Prehistoric Europe

Use 300-400% WOF of ripe blackberries. For 100 g of wool, gather 300-400 g of fully ripe berries. Blackberries must be completely ripe — dark purple-black all over, soft, and juicy. Under-ripe berries (with red sections) contain less anthocyanin and produce weak, pinkish results. Frozen blackberries work well — freezing breaks cell walls and releases more juice. Wash to remove insects and debris.

Place the blackberries in a dye pot and crush them thoroughly with a potato masher or wooden spoon. Add 4 litres of water. The mixture will be a vivid dark purple. Break up all whole berries — unbroken berries waste their dye content. The seeds are small and hard and will be strained out later.

Bring the pot to a gentle simmer (70-75°C) and hold for 30 minutes. Do not boil — anthocyanins degrade rapidly at high temperatures, shifting the colour from purple toward dull brown. Keep the temperature moderate and stir occasionally. The liquid will be a deep, opaque purple.

Strain the dye liquor through a fine mesh strainer into a clean pot. Press the pulp firmly to extract all remaining purple liquid. Seeds and pulp trapped in the wool will cause spotty, uneven colour — strain thoroughly. For cleanest results, strain a second time through muslin cloth. The strained liquor should be a clear, deep purple.

Pre-wet the alum-mordanted wool in lukewarm water for 15 minutes, squeeze gently, and lower it into the blackberry dye bath at room temperature. Slowly raise to 70°C over 15 minutes, then hold for 45 minutes. Turn gently every 10 minutes. The wool will develop a soft purple-grey to dusty mauve. The alum mordant helps fix the anthocyanins and produces a cleaner purple tone than un-mordanted wool, which tends toward grey.

Turn off the heat and let the wool cool in the dye bath overnight. Remove, squeeze gently, and rinse in lukewarm water — the rinse water will run purple for some time. The final colour is a soft, muted purple-grey to dusty lavender — gentle and natural-looking. Lightfastness is poor — blackberry purple will fade noticeably within a few weeks of sunlight exposure, eventually settling to a warm brownish-grey. For this reason, blackberry-dyed items should be stored away from direct sunlight. Despite this limitation, the fresh colour is beautiful and the process is an ideal introduction to natural dyeing. Dry in shade.