Heavy wool blankets or wool-lined slippers might evoke ideas of itchy, coarse fabric, but put those thoughts aside — Merino wool is different. Merino wool is notoriously fine — with fine, fragile, and soft fibers.
Merino garments are even measured by the tiny diameters of the fibers, called microns. Most Merino wool shirts we tested used wool that measured between 17.5 and 20 microns.
And the smaller the microns, the finer the fabric. If you are looking for the softest merino layer money can buy, you’ll want to look somewhere in the 15-17-micron fabric range.