Your pores are fully open in the sauna. What your hat is made of matters more than most brands want you to know. A maker with 15 years of hand-felting explains why undyed wool is the only material that makes sense — for infrared sauna, contrast therapy, and cold plunge.

Why undyed, lanolin-rich wool makes such a good sauna hat, and how I use mine between sauna heat and the cold plunge. Wool around your head, water only, no dyes.