Fine, medium, coarse: why strand width matters
Strand width, how thick each individual hair fibre is, is one of the most underused pieces of information in building a haircare routine. Here is what it tells you.
Fine hair has a smaller diameter, which means a higher surface-area-to-volume ratio. It reacts quickly to products, both positively and negatively. Fine hair is often protein-sensitive and can become limp under heavy oils or butters.
Coarse hair has a thick diameter and a dense cortex, making it more resistant to damage in some ways, but also more difficult to penetrate with moisture. Products need to be richer and more concentrated to have an effect.
Medium strand width is the most common and tends to respond predictably to most products.
Fine and medium hair often benefits from lighter, water-based products. Coarse hair typically needs heavier emollients and can handle proteins without the same risk of stiffness or breakage.