Man-made fibres and clothing

Fabrics are made from natural and man-made fibres. Man-made fibres are of two kinds: artificial fibres come from natural raw material (wood or cotton cellulose, glass), while synthetic fibres come from substances made by processing coal, oil and gas. Artificial silk is of three kinds: viscose (from wood cellulose, the commonest), copper-ammonia and acetate silk. The most used synthetic fibres are capron (nylon), lavsan (polyester), nitron (acrylic), chlorin and anid. Man-made fibres are produced in factories by complex chemical methods that use dangerous chemicals, so at school it is only studied in theory. Staple is short-cut fibre from which yarn is spun, mixed with wool or cotton or pure. Viscose silk is glossy, weaker than cotton, weaker still when wet, and creases a lot. Acetate loses 30–35 % of its strength when wet and cannot stand high heat. Synthetic fibres are soft, strong and crease little, their pleats hold after washing, their dye does not fade and they do not rot; their drawbacks are low moisture absorption and building up static charge. Capron is very strong for its weight, and lavsan resists heat. They can be tested by burning: viscose burns like paper and leaves ash, capron and lavsan melt, smoke and form a hard bead. Safety: burn tests are done only by the teacher (a small sample held with tongs or tweezers, a bowl of water, an open window, hair tied back, no loose flammable clothing). Molten synthetic drips burn the skin and the smoke is harmful. Pupils do not burn samples; they study properties by stretching, crumpling and dripping water. With a microscope do not touch the lens and never aim a light source straight at the eyes. Synthetic items are usually washed at 30–40 °C and ironed at a low setting as the label shows (one-dot iron, up to about 110 °C).