Linen is a durable fabric made from flax plant fibres. It is up to three times stronger than cotton. Linen can survive many washes and even gets softer the more it's washed. This may explain why linen fibres are used to make towels, bed sheets, table cloths and other items that are frequently washed. Because it is an off white or light beige colour, linen is easily dyed and maintains its colour after many washes.
Prewash the linen in hot water and washing powder or washing up liquid, removing any dirt and grease.
Dissolve the non-iodised salt in the 11.3 litres (3 gallons) lukewarm water in a washing machine or bath. A bath is recommended for 454 g (1 lb) of fabric. A washing machine is recommended for up to 3.63 kg (8 lb)of fabric.
Add the calsolene oil. This step is optional. It helps the linen dye more evenly.
Dissolve the fibre reactive dye by mixing it with the urea water. The amount of fibre reactive dye you use depends upon the colour. For most colours you only need 1 tbsp of dye. When dyeing your linen a darker colour, you may need 2 to 4 tbsp of dye. Read the fibre reactive dye package to be sure of the amount of colour needed. Add this dye mixture to the washing machine or bath of lukewarm water.
Add the linen to the dye water. If you're using a bath, stir every 3 to 4 minutes for 20 minutes. If you're using a washing machine, set it to the agitate setting for 20 minutes. Make sure all of the fabric is submerged in the dye water.
Dissolve the soda ash in warm water and add to the dye water. If using the washing machine, turn the machine off. Move the linen to one side of the washing machine or bath as you stir the soda ash mixture in with the dye water. The soda ash mixture should be completely mixed in with the dye water alone before stirring in the linen again. This prevents the fabric from having discoloured spots.
Stir the linen around again every 3 to 4 minutes or set the washing machine again to the agitate setting. Stir light colours for 30 minutes and dark colours for an hour.
Remove the linen from the dye water and rinse out any extra dye. If using a washing machine, run the linen through the rinse cycle once.
Repeat step 1, washing the linen again with hot water and fabric or dish detergent to remove any extra dye.
If possible, test a small piece of linen fabric before dyeing a larger amount. The amounts of non-iodised salt, calsolene oil, and fibre reactive dye listed are based on dying 454 g (1 lb) of linen fabric. If you're dying additional pounds of linen, you would need to multiply the quantity of these ingredients by the amount of linen.
Some of the substances used in the process are harmful and may cause skin irritation. Handle all substances with care and keep away from children. The dye may damage other clothing and fabrics.