Their exact quality is determined by various structural characters and the accompanying materials and their proportions.

Animal hair

The use of animal hair goes back to the most ancient times. Originally, the skin was used together with the hair, then after domestication of animals, only the hair itself was used - the type of animal and the purpose varied from culture to culture. The hair of sheep and goats were used almost everywhere, but camel and llama hair was also common. In a broader sense, wool refers to the hair of all herbivorous domestic animals. Wool, as an elementary fibre, as a particular hair, is a complex system of follicle and epidermis. Animal hair can also contain byproducts or fats from the animal's skin, such as lanolin in wool. The additives soften, impregnate, and make the animal's fur more resistant. The surface of the fur is scaly, and based on its pattern, size and morphology, it is possible to identify which animal the given fur comes from. Scales also play a role in felt production: the scales that open due to moisture are mechanically worked together, then the overlapped scales are closed when they dry, holding the fibres together.

The yarn manipulators played an important role in wool processing: based on the quality of the material, they determined what it would be most suitable for. For example, shorter, softer hairs are better for making socks, stockings, and cardigans, while rougher, greasier, longer hairs are more suitable for making felt or jacket fabrics.

Glandular secretions

We include insect-generated fibres in the category of glandular secretions. The processed forms of glandular secretions are called silks, like caterpillar silk or spider silk. Caterpillar silk was a known material in China as early as the 3rd millennium BC. The quality of the silk is greatly influenced by the quality of the food, i.e. the mulberry leaves, and by temperature and humidity conditions. The silk is harvested from the adult pupa before the moth hatches, using hot water, which dissolves the silk glue called sericin. A silk thread is about 500 metres long when unwound from the cocoon. It was popularly used mixed with wool on wall tapestries and carpets. It is also common for silk and wool to be used together on sofa upholstery. They do this to make the fabric more beautiful by weaving a glossy silk between the less shiny wool. In some designs, the play of light was essential to depict and emphasise certain details.

Spider silk is much more complicated to produce than caterpillar silk, and because of its low silk yield, it could only be used to make very expensive textiles, so it was not as widely cultivated. The term wild silk or wild silkworm moths, which refers to relatives of the silk moths that were not bred but collected by nomadic peoples, is mainly found in Asian-themed collections. Their quality varies and they can even be excellent, but their colour is usually greyish, brownish or yellowish rather than white.