Merino Wool

Merino wool is shorn from merino sheep bred for exceptionally fine fleece (often 18 microns or finer), then scoured to strip grease and dirt. Much of it is also given a superwash finish: a chlorine bath that erodes the fiber scales followed by a Hercosett polymer resin coating, a treatment that introduces chlorinated residues.

Peer-reviewed dermatology directly debunks the myth that wool is a universal allergen. A 2017 review in Acta Dermato-Venereologica concluded that wool fiber is not a cutaneous allergen; the itch is non-immune irritant contact dermatitis caused by stiff fibers mechanically stimulating your skin's nerve endings. Because merino sits well under the roughly 30-to-32-micron prickle threshold, it is well tolerated and may even benefit eczema-prone skin. Two real concerns remain. First, the superwash chlorine-Hercosett process leaves a nylon-based resin film and chlorinated byproducts on the fiber that can bother sensitive skin. Second, residual lanolin is now extremely low in modern scoured wool (under 0.5 percent), usually below the level that triggers a reaction, so true lanolin sensitivity is rarer than blamed. Merino also breathes and thermoregulates well, wicking moisture to keep you dry.

Choose fine merino around 17 to 18.5 microns, prefer untreated or non-superwash where possible, and look for OEKO-TEX STANDARD 100 plus Responsible Wool Standard (RWS) certification.

Merino welfare's biggest flag is mulesing, cutting skin from a lamb's hindquarters to prevent flystrike, often without pain relief; RWS-certified wool prohibits it.