Mad as a Hatter

The process of making fabric called felt goes back to ancient civilization and may even predate spinning and weaving. The undercoat of certain animals—including rabbit, muskrat, and beaver—contains microscopic scales that cling together. The pelts were shaved to obtain this underhair which was repeatedly submerged in boiling water, then drained and kneaded like bread dough. This caused the scales to open and cling together. The drying process caused the scales to shrink, thus locking them together to form a solid fabric. Felt makers discovered in the 1600s that mercuric nitrate, when brushed on the fur, causes the scales in the fur to open farther and thus increase in strength, improving the quality of the felt. Hat makers spread the felt over a hat form and pressed and steamed it into shape. Then they brushed the fabric to a sheen. Beaver fur, because of its waterproof qualities, its softness and resilience, was most sought after. The Hudson’s Bay Company capitalized on beaver pelts, which brought about the exploration and exploitation of the habitats of these animals.

Fur trappers arrive at Lolo Hot Springs, Montana, with loads of fur, c. 1890.
Montana Historical Society Photograph Archives, Maloney Collection

Beaver hats were a status symbol, and the industry nearly caused the animal’s extinction here in Montana and elsewhere. Fashions fortunately changed when silk came into favor. The beaver’s near extinction was not the only legacy of the beaver hat industry. Exposure to the mercury fumes in poorly ventilated workshops caused poisoning characterized by trembling, loss of coordination, slurred speech, loosening of teeth, memory loss, depression, irritability, anxiety, and mental illness causing hatters to go crazy. Thus the term “mad as a hatter” is not a joke.