Discharge Dyeing & Printing with Acid Dyes

Fabric artists today spend as much time taking colour out as putting it in. This gives their fabrics a richness that is only obtained by putting this extra thought into the finished article.

White fabric can be dyed with a wealth of dyes such as Acid, Fibre Reactive Procion MX and Deka L dyes, natural plants such as indigo and chemicals like Fast Black K, iron and tannic acid.

The Fibrecrafts Dischargeable Acid Dyes and Illuminating Acid Dyes increase the range of patterning and effects available. The dyes work like this; the dischargeable acid dyes have a low resistance to bleaching. They are easily removed from fabric while the illuminating dyes have a high resistance to bleaching. The image shows discharge printing on dischargeable black velvet.

The dyes offer an interesting and varied technique. Fabrics can be painted or dyed with the dischargeable dyes which are readily removed with discharge paste. This alone offers a variation on the resist technique. Combining discharge paste (formosul and indalca), or Jacquard Discharge Paste, with an Illuminating dye has the effect of replacing the bleached out area with the colour from the Illuminating dye. After steaming and drying, the fabric is washed in cold and then hand hot water to remove all surplus dye and chemicals.

Another method of discharging is to make a discharge paste from 1 part Soda Ash to 4 parts Thiourea Dioxide and then applying heat by ironing. This gives you time to watch the discharge process and stop it when the fabric has discharged to a colour that you want. For example, black will go through different phases of colour loss. You can stop the process at any time by rinsing the fabric in cool water.

Modern irons are very limited in the highest temperature they can achieve. This may be below that required to set dyes or discharge. If you are finding problems with this, it may help to check through garage sales for an old iron for your work.

Dischargeable Black Fabrics

These black dyed fabrics can be used readily for printing with discharge paste. The discharge paste can be combined with Illuminating Acid dye which replaces the dischargeable black dye. There is a choice of silk/viscose Velvet, Gauze Chiffon (pictured right) and Habotai 8mm.

Remember to Prepare for Dyeing!

Before dyeing, it is important to check whether the item is ‘Prepared for Dyeing’ (PFD) or requires scouring to remove any grease, oil or starch. Run a few droplets of cold water onto the fabric. If they soak in quickly, no scour is necessary. To remove starches, size and oils, add 5mls of Synthrapol (a non-ionic detergent) along with 2-3 litres of water for each 100gms of material. Stir gently over a 15 min period, and then rinse thoroughly in warm water. It is possible to use household detergent, but the alkaline residue may affect the final colour or wash fastness.

METHOD for Discharge Dyeing

A concentrated stock solution of dye (made using water and vinegar as the acid) is combined with a discharge paste made from Indalca and Formosul. The paste is applied to the ready dyed fabric with a brush, stamp or screen. When dry, the discharge paste and the dye it carries is activated by pressing the fabric with a hot iron on a steam setting then rinsing away the surplus dye and chemicals.

Safety of Dyes and Precautions

There is no substantiated evidence of a causal link between exposure to these dyes and any chronic or fatal illnesses. Both the acid and fibre reactive dye families have a considerable track record, of use in industry in considerable quantities and in a less well controlled environment in the crafts.

Sensible precautions to be taken when handling dyes and chemicals, particularly as powders:

• Avoid inhaling dusts, they can produce an asthma type reaction. People with known respiratory problems should not handle synthetic dyes, and particularly the fibre reactive dyes, in powder form. A dust mask should be worn when working with the powders or exposed to an aerosol from spraying dye solutions made up in water
• Avoid splashing solutions into the eyes, swallowing the materials or prolonged skin contact. A simple ‘non-contact’ approach (most people use gloves to avoid dyeing themselves) plus normal, good, hygiene is sufficient precautions for the occasional user
• Store in clearly labeled containers well away from children, pets and foodstuffs. Treat dye powders and solutions with the same caution as domestic poisons (eg strong cleaners, bleaches or medicines)
• Dispose of spent solutions containing residues of the dyes responsibly. Dilute and pour onto waste land or into the sewage system. They have no known effect on the environment when used in the quantities recommended in the literature