A Micron (micrometre) is the measurement used to express the diameter of Wool fibre. What is usually referred to as Wool’s “micron” is the mean of the fibre diameter or average diameter. Fibre diameter is the most important characteristic of Wool in determining its value.
Raw Wool above 26 Microns is called Semi Merino and Wool from 25 Microns to 29 Microns are used in Felts, in car roof tops, sound speakers, home theatres and felted yarn. It is a special type of yarn and requires Wool ranging from Micron 25-29.