The Billy Lids

Have you ever noticed the effect that colour has on our emotions? It isn't surprising that throughout history humans have chosen to add colour to fabrics, employing the process known as dyeing.

Dyes Used in Early Centuries

Until the second half of the 29th century, the substances used for dyeing fabrics came entirely from natural sources, such as plants, insects and shellfish. For example, the woad plant prodeced a blue dye, the weld plant a yellow dye, and the madder plant a red dye. A black dye came from the logwood tree, and a lichen named archil gave a violet dye. The murex shellfish produces a very costly purple dye, known as Tyrian, or imperial, purple. This dye coloured the garments worn by Roman emperors.

Long before there were Roman emperors, the prominent and wealthy wore clothes dyed with natural substances. Red dyes, for example, were produced from the female kermes insect.

The Process of Dyeing

Most dyeing processes are far more complex than simply dipping yarn or material into a dye solution. In many cases one stage of the dyeing process involves the use of a mordant, which is a substance that has an attraction for both the fibre and the dye. Through its use, dye bonds to the fibre and ceases to be water-soluble. Many chemicals are used as mordants, some of which are dangerous to handle.

Some dyeing processes create unpleasant smells. One of these is the lengthy and complex process that was used to produce Turkey red. This dye was used on cotton and produced a bright-red colour that was not affected by light, washing or bleaching. At one time the process involved 38 different stages and took as long as four months to complete!

The Arrival of Synthetic Dyes

The first dye that was not derived from natural sources is attributed to William Henry Perkin in 1856. Perkin discovered mauve, or mauveine, an intense purple dye. By the end of the 19th century many other synthetic dyes in brilliant colours had been developed. Today over 8,000 types of synthetic dyes are manufactured. The only natural products still in regular use are logwood and cochineal.

Challenge to Colour Fastness

When we buy clothes or materials, we want them to be colourfast. Nevertheless, many fade in sunlight or with repeated washing, particularly if detergents are used. Sometimes fabrics may discolour from perspiration or change colour when washed with other clothes. Fastness during the washing process depends on how strongly the dye molecules adhere to the fibres. Repeated washing and the effects of detergents designed to loosen stains separate the dye from the fibres, resulting in colour loss. Dye manufacturers test their products to see if the effects of light, washing, detergents and perspiration are within acceptable limits.