Linnaeus mentions that a beautiful red colour may be prepared from the Lichen Gyrophora pustulata. G. Cylindrica is used by Icelanders for dyeing woollen stuffs a brownish green colour. In Sweden and Norway, Evernia vulpina is used for dyeing woollen stuffs yellow. Iceland Moss, Cetraria Islandica, is used in Iceland for dyeing brown. Usnea barbata is collected from trees in Pennsylvania, and used for an orange colour for yarn.
A general method for using lichens is suggested by Dr. Westring of Sweden in his Experiments on Lichens for Dyeing Wools and Silks:
"The Lichens should be gathered after some days of rain, they can then be more easily detached from the rocks. They should be well washed, dried, and reduced to a fine powder: 25 parts of pure river water are added to 1 of powdered lichen and 1 part of fresh quick lime to 10 parts powdered lichen. To 10 lbs. lichen half a pound sal ammoniac is sufficient when lime and sal ammoniac are used together. The vessel containing them should be kept covered for the first 2 or 3 days. Sometimes the addition of a little common salt or salt-petre will give greater lustre to the colours."
This method can be followed by anyone wishing to experiment with Lichens.
Dr. Westring did not use a mordant as a rule. Where the same species of Lichen grows on both rocks and trees, the specimens taken from rocks give the better colours.
Orchil or Archil and Cudbear are substantive or non mordants dyes, obtained from Lichens of various species of Roccella growing on rocks in the Canary Islands and other tropical and sub-tropical countries. They used to be made in certain parts of Great Britain from various lichens, but the manufacture of these has almost entirely disappeared. They have been known from early times as dyes. They give beautiful purples and reds, but the colour is not very fast. The dye is produced by the action of ammonia and oxygen upon the crushed Lichens or weeds as they are called. The early way of producing the colour was by treating the Lichen with stale urine and slaked lime and this method was followed in Scotland. Orchil is applied to wool by the simple process of boiling it in a neutral or slightly acid solution of the colouring matter. 3% Sulphuric acid is a useful combination. Sometimes alum and tartar are used. It dyes slowly and evenly. It is used as a bottom for Indigo on wool and also for compound shades on wool and silk. For cotton and linen dyeing it is not used. It is rarely used by itself as the colour is fugitive, but by using a mordant of tin, the colour is made much more permanent.
Many of the British lichens produce colours by the same treatment as is used for producing Orchil. Large quantities were manufactured in Scotland from lichens gathered in the Shetlands and Western Highlands. This was called Cudbear. The Species used by the Scottish Cudbear makers were generally Lecanora tartarea and Urceolaria calcarea; but the following lichens also give the purple colour on treatment with ammonia:—Evernia prunastri, Lecanora pallescens, Umbilicaria vellea, U. pustulata, Parmelia perlata. Several others give colours of similar character, but of little commercial value. The manufacture of Archil and Cudbear from the various lichens is simple in principle. In all cases the plant is reduced to a pulp with water and ammonia, and the mass kept at a moderate heat and allowed to ferment, the process taking two or three weeks to complete.
RECIPES FOR DYEING WITH LICHENS
To dye Brown with Crotal. For 6-1/4 lbs. (100 ozs.) of wool. Dye baths may be used of varying strengths of from 10 to 50 ozs. of Crotal. Raise the bath to the boil, and boil for an hour. A light tan shade is got by first dipping the wool in a strong solution of Crotal, a darker shade by boiling for half-an-hour, and a dark brown by boiling for two hours or so. It is better, however, to get the shade by altering the quantity of Crotal used. The addition of sufficient oil of vitriol or acetic acid to make the bath slightly acid will be an improvement (a very small quantity should be used).
To dye red with Crotal. Gather the lichen off the rocks—it is best in winter. Put layers of lichen and wool alternately in a pot, fill up with water and boil until you get the desired tint. Too much crotal will make the wool a dark red brown, but a very pretty terra cotta red can be got. No mordant is required.