In the earliest times, tartans such as the "Falkirk" were produced in only the natural colours of the wool. However, the introduction of coloured dyes allowed much more interesting cloth to be produced.

The dyes were produced from lichen, tree bark, plant roots, or from the leaves and berries of plants and trees. The wool was prepared by first washing the wool and removing the oils, and then soaking the wool in an alkaline solution - usually made by adding soda ash prepared by burning seaweed. The washed wool, either before or perhaps after spinning, was then soaked in the dye. To make the dye the plant material was boiled in water, sometimes taking up to 14 days, during which time the dyestuffs would come out into the water. The dyeing was made permanent by adding a chemical "fixer" called a mordant - a metal salt, frequently Alum, Iron, or Copper. In many cases the dye was not formed unless a mordant was included in the boiling process.

When you see how complicated some recipes are it is quite remarkable that they were discovered. Dyeing is frequently a matter of experimenting and chance. The dye-colour that a particular plant produces can depend on the time of year it was picked, the type of soil grown in and where, as well as the climate of the area. The type of mordant, too, can also dramatically alter the colour of the dye. For instance, heather flower tops produce a yellow dye when Alum is used as a mordant, while Chrome produces a much deeper yellow. And dock leaves picked early in the year (February) produce red dye when Chrome is used as mordant, but produce yellow when Alum is used; and when picked later in the year the leaves produce a golden coloured dye when chrome is used as a mordant, while copper produces a green dye, and iron a darker green dye.

Because the weavers were restricted to the colours they could produce from the local vegetation, tartans produced in the area were frequently reproduced in the same colours and frequently even in the same pattern. This tradition is maintained today in the wearing of the modern district tartan patterns Crieff, Galloway, Aberdeen, etc.

Unfortunately the natural dyes couldn't be produced on a commercial scale. With the increase in trade in the 18th century, it was only natural that many of the dyes were replaced by imported dye-stuffs such as Lichen species of the warm Atlantic sea coasts. By the 1700's, indigo, the most precious blue dye known before the discovery of man-made dyes, was regularly being shipped to St. Kilda. Originally imported from Holland where it had been used since the 16th century, it was first introduced there from Italy.

Continued: More on Dyes