Treating with alum as mordant

For all dyeings presented here, you have to treat the wool with alum (potassium aluminium sulphate) KAl(SO4)2 . 12 H2O first. This treatment makes the plant dye stick to the wool fibre.

Recipe for 100 g wool (3 oz):

Dissolve 15 g alum in a cup of hot water and pour it in 3-5 litres of water. Put the wet wool in this fluid and heat it to 70°C (158°F). Keep this temperature for 1 hour, then let the wool cool down in the fluid. Rinse the wool.

 

 

Yellow dyed with heather (Calluna vulgaris)

(Before dyeing, the wool must be treated with alum first!)

Recipe for 100 g wool (3 oz):

Cook 300 g dried or 500 g fresh heather in 5 litres of water for 1-2 hours. Let cool down. Sieve. This fluid is the dye-bath. Put the wet wool in it and heat to 70°C (158°F). Dye at this temperature for one hour. During this time immerse the wool and move it from time to time. Let the wool cool down in the dyeing bath. Take it out and rinse until the water stays clear. Put the wool in a vinegar bath (1 tablespoon of vinegar in 3 litres of water) for 10 minutes. Squeeze the wool gently and spread it out to dry.

 

 

 

Orange dyed with madder (Rubia tinctoria)

(Before dyeing, the wool must be treated with alum first!)

Recipe for 100 g wool (3 oz):

Soak 60 g (2 oz) of dried cut madder root overnight. The next day you tie the soaked madder root into a piece of gauze. Put it in a pan and add 5 litres of water. Add the wet wool. Heat slowly to 60-70°C and keep this temperature for 1 hour. Attention: The temperature must not exceed 70°C (158°F) because the color changes to brown if it is too hot! During the dyeing time immerse the wool and move it from time to time. Let the wool cool down in the dyeing bath. Take it out and rinse until the water stays clear. Put the wool in a vinegar bath (1 tablespoon of vinegar in 3 litres of water) for 10 minutes. Squeeze the wool gently and spread it out to dry.

 

 

Red dyed with cochenille (Coccus cacti)

(Before dyeing, the wool must be treated with alum first!)

Recipe for 100 g wool (3 oz):

Bring to the boil 10 to 15 g Cochenille powder in a litre of water. Add 2 litres of cold water. Dissolve 6 g tartaric acid (Acidum tartaricum) C2H2(OH)2(COOH)2 in a cup of hot water and pour it into the dye bath. Add the wet wool and heat to 70°C (158° F). Dye at this temperature for one hour. During this time immerse the wool and move it from time to time. Let the wool cool down in the dyeing bath. Take it out and rinse until the water stays clear. Put the wool in a vinegar bath (1 tablespoon of vinegar in 3 litres of water) for 10 minutes. Squeeze the wool gently and spread it out to dry.

 

 

Blue dyed with real vegetable indigo

(For this dyeing it is not necessary to treat the wool with alum)

Recipe for 100 g wool (3 oz):

Mix 2 g of vegetable indigo powder with a small amount of methylated spirits. Heat 3,5 litres of water to 55° C (131°F). Cautiously sprinkle 7 g of hydrosulphite onto the water. Add 14 ml of ammonia 10% and the Indigo. Cover the dye-bath and keep it on the temperature (55°C) during 45 minutes.

After this time put the wet wool into the dye-bath and immerse it carefully. Let the wool dye during15 to 20 minutes. Take the wool out (don't rinse it!) and hand it up in a airy place. The oxygene of the air changes the color from yellow to blue. Leave the wool in the air for about 15 to 30 minutes, then rinse it until the water stays clear. Put the wool in a vinegar bath (1 tablespoon of vinegar in 3 litres of water) for 10 minutes. Squeeze the wool gently and spread it out to dry.

Some explanations to the indigo dyeing:

The indigo dyeing bases on a reduction- and oxidation-process. Indigo isn't water-soluble. It has to be changed to indigowhite through a reduction agent (hydrosulphite) to become watersoluble. The reduced indigowhite sticks to the wool fiber. The wool looks yellowish in the dye-bath. If the (yellow)dyed wool is taken out of the bath, the oxygene of the air oxidizes the indigowhite and changes it to blue indigo. The indigo keeps combined with the fiber because it is insoluble in water.

Hydrosulphite: sodiumhydrosulphite or sodiumdithionite. Na2S2O4. Reduction agent for dyeing with indigo.

Ammonia 10%: NH4OH 10%

 

 

Green dyed with heather/indigo

In a first step you dye the wool yellow with heather, then you dye with indigo to get green.

 

 

Violet dyed with cochenille/indigo

In a first step you dye the wool red with cochenille, then you dye with indigo to get violet.

 

© Ursula + Pascal Glauser 28.10.99

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