stems and seeds of apples, shells of nuts or the outer leaves of purple cabbage can provide a wealth of colours and the range of materials changes with the seasons. Some plants only yield good results when freshly-picked and some can be dried for later use. Generally, flowers such as dandelion, goldenrod and hollyhocks give the richest colours when used fresh. If these are left to dry, the chromophores degrade and the colours produced are muted. Other dyestuffs such as birch bark and rhubarb roots can be dried for later use. The dyestuff should be dried out of direct sunlight in a well- ventilated area and stored in a paper (not plastic) bag. As a general rule, you should use the same weight of dyestuff as fibre to be dyed. The amount of water does not dilute the dyestuff. Rather, the strength of the dye is a function of the number of dye particles relative to the amount of material to be dyed. The colour particles in the dyestuff are ‘shared’ among the fibres.


Charging the Dyebath with Colour If flowers are being used, place them into the dyepot, cover


with boiling water and leave to steep overnight. The mixture will cool gradually and should be covered. There may be enough colour in the dyebath after this steeping. If not, sim- mer on a stovetop for an additional 30 minutes. Bark or nuts will need significantly longer to prepare. They should be soaked in water at room temperature in a covered pot for at least one week. After the week they can be simmered gently for an hour or more. Berries are much more colour-potent so it is a faster process to extract the dye. Crush the berries and add them to dyebath water. Simmer for an hour or so and then turn off the heat. Leave in the covered pot to cool overnight.


Introducing the Fibre to the Dyebath After the dyebath has been charged with colour, sieve the


solid dyestuff (flowers, bark or berries) out of the liquid. Now you are ready to start dyeing! This may be done using a cool or a hot technique.


Cool dyeing techniques may be more suitable for


younger students. Colour development in plant-based fibres often responds well to this technique. In this method, tex- tiles are added to the dyebath and stored for a given period of time, out of direct sunlight. With some dyestuffs such as flowers, an overnight soak will be adequate. For others such as leaves and seeds, several days may be required for ade- quate colour to develop. In the hot dyeing method, the textile is placed into a cool


dyebath and then the pot is gently heated until the dyebath reaches a simmer. The dyebath is usually simmered for 30 minutes to one hour, removed from the heat and left over- night. The pot can be heated using a conventional stovetop or a slow cooker. All natural dyes can be divided into those that need a


mordant (adjective or fugitive dyes) and those that don’t (substantive dyes). A mordant is an additional substance that facilitates the binding of the dye particles to the fibre (from the Latin word ‘mordere’ meaning ‘to bite’). Substantive dyes are usually those that are rich in tannins such as tree barks and nuts. These tannins work as built-in mordants.2


Mordants It is likely that these natural dyeing techniques developed


as a by-product of daily food and drink preparations. The processes of cooking food and fermenting fruit for alcoholic beverages are similar to those of dyeing fibre. The earliest dyeing experiments probably produced a stain that faded quickly in the light or that washed out when the fiber was wet. Preparing hides for leather may have led to the discov- ery of tannin-rich tree barks as natural mordants. Mordants are often metallic compounds of aluminum,


iron or copper. Chrome and tin mordants are used by expe- rienced dyers but are too toxic for young novices. Instead, some natural substances such as tree barks and nuts can be used as mordants for adjective dyes. The most effective way to treat fibre with a mordant is before the dyeing process. Alum powder (aluminum ammonium sulphate) is used in


GREEN TEACHER 113 Page 31


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