Dyeing Brown-Black with Alder Bark — The Northern European Dark Dye

Use 100-200% WOF of dried alder bark. For 100 g of wool, weigh out 100-200 g of dried bark. Harvest bark from freshly cut branches or fallen timber — the inner bark (cambium) is richest in tannins and should be a reddish-orange when fresh. Strip bark from branches with a drawknife or sharp knife, then dry in shade for 1-2 weeks. Break dried bark into 3-5 cm pieces. Fresh bark can be used immediately at double the weight.

Place the bark pieces in a dye pot with 4 litres of warm water and soak overnight (8-12 hours). The water will turn a deep reddish-brown within the first hour as tannins dissolve rapidly from the bark. By morning, the liquid should be a rich, dark brown with a reddish undertone. The bark pieces will have softened and darkened.

Bring the pot to a gentle simmer (80°C) and hold for 45 minutes. Stir occasionally. The liquid will deepen to a very dark reddish-brown. Alder bark extracts efficiently at moderate temperatures — longer simmering does not significantly increase colour depth but can make the dye bath muddier. The bark will darken and become soft and pulpy.

Strain the dye liquor through a fine mesh strainer into a clean pot. Press the bark to extract all remaining liquid. Bark fragments will tangle with wool and cause uneven spots — strain thoroughly. The strained liquor should be a deep, clear reddish-brown.

Pre-wet wool in lukewarm water for 15 minutes, squeeze gently, and lower into the alder bark dye bath at room temperature. Slowly raise to 80°C and hold for 45 minutes. Turn gently every 10 minutes. Alder bark tannins bond directly to protein fibres — no mordant is strictly required for brown shades. However, alum mordanting gives a warmer, more golden brown, while iron modification after dyeing shifts the colour dramatically toward dark grey-brown or near-black. For the darkest shades, dip the dyed wool briefly in iron water after the alder bark bath.

Turn off the heat and let the wool cool in the dye bath overnight. Remove, squeeze gently, and rinse in lukewarm water until the runoff is mostly clear. The final colour without modifiers is a warm, reddish-brown — deeper and more red-toned than oak bark. With iron modification, alder bark produces one of the most convincing near-blacks achievable from a European tree bark, rivalling logwood. Washfastness is excellent due to the strong tannin-fibre bond. Lightfastness is good. Dry in shade.