Cashmere vs Merino Wool

With cashmere, your comfort is decided almost entirely by processing quality, not the species. Fine cashmere down is well below the roughly 30-to-32-micron threshold at which fibers stiff enough to mechanically jab your skin's nerve endings cause prickle, the itch that most people mistake for an allergy. But it takes only a few overlooked guard hairs to make luxuriously soft cashmere scratch and irritate, the so-called prickle factor, and two cashmeres with identical average microns can feel completely different depending on how well those coarse hairs were removed. Cheap cashmere is usually cheap because it skipped thorough dehairing. As with all goat and sheep fibers, an itch reaction is a physical, non-immune irritant contact dermatitis, not a true allergy.

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.