Nylon is a synthetic material that is often used to provide structure, stability and strength to yarns made with other, softer fibres. A nylon content of at least 15% is recommended for socks.

Mulesing is a controversial farming practice used, predominantly in Australia, to prevent the parasidic infection flystrike. While mulesing prevents infection, it is a very painful procedure for the animal to endure, and more humane alternatives exist. This practice is banned in many areas of the world. If a yarn is marked as mulesing free, that means that no animals were treated this way during the production of the yarn.

Superwash is a treatment method that is used to make wool fibres more resistant to shrinking and felting. There are a different methods used to achieve this, and the methods vary in terms of durability and environmental impact. These yarns often take dye very well, and tend to have a lot more drape and stretch than non-superwash yarns. A hand-dyed yarn may be superwash yet still recommend hand washing: this is to extend the colourfastness.

Merino sheep create a wool with a long, smooth fibre that is lightweight, warm, and soft. Like all wool, it has excellent breathability and does an excellent job regulating temperature in garments. It is a very popular type of wool to use for hand knitting yarn, and is a great choice for socks and garments worn close to the skin.