BLUES, GREEN, PURPLE , BROWNS and BLACK
On the left of this picture (unfortunately rather dark) are two shades of blue from a woad fermentation vat, green from dyer’s broom yellow overdyed in the woad vat and purple from the lichen Ochrolechea tartarea. On the right are some browns from walnut leaves and hulls and alder bark and twigs. The black shades are from walnut, oak and alder plus iron water modifier.
Black can be achieved either by dyeing red, yellow and blue in succession over one another, and repeating the overdyeing until a suitable depth of black is reached, or by using the tannin/iron complex.
To use the tannin/iron complex, wool is mordanted with tannin, or dyed in a tannin-rich dye such as oak galls, oak or bramble leaves or alder bark, (or indeed a combination of several tannin-rich dyes), then modified in an iron solution. The depth of colour is best built up by repeatedly simmering the fibres in the iron solution, then airing them for about half an hour to allow the colour to develop. This process can be repeated until a rich black is achieved. Unfortunately, this method tends to weaken wool fibres over a period of time, so the dyed materials will gradually deteriorate. However, if you are not dyeing for posterity it is the simplest way to achieve black.
This picture shows some skeins dyed purple using the lichen Ochrolechea tartarea. They are lying on a piece of old woollen blanket, also dyed lichen purple. The shades are actually more purple in tone and deeper in colour than this photo suggests
The lichen is steeped for several weeks in stale 4-week-old urine (or a solution of 1 part ammonia to 2 parts water), until the liquid becomes deep purple or almost black in colour. The solution should be stirred or shaken vigorously two or three times daily to incorporate oxygen. The liquid is then poured off and water added to make the dyebath. The fibres are then gently simmered in the dyebath for about 45 minutes, then left to cool in the dye liquid. This simmering and cooling process can be repeated several times to increase the depth of colour.
In addition to the colours illustrated by my test samples, many more shades could be achieved by dyeing one colour over another. I think the experiments described in these three posts show that the early Anglo-Saxons would have been able to produce a wide range of colours without using mineral alum or other chemicals dyers tend to rely on today. One of my aims as a dyer is to achieve reliable colours using a minimum of manufactured chemicals and the results of these tests indicate that there is further scope for experimentation in this area.