Felt Hat Day

What the day is

Felt Hat Day is observed on September 15, traditionally the point in the year when straw hats were put away and felt ones came out. Construction is covered on the Make a Hat Day entry that shares this date; this one is about the felt.

Origin and background

Felt is not woven. It is made by matting fibers together until they lock, which works because a wool fiber is not smooth but covered in microscopic overlapping scales. Under heat, moisture and agitation those scales ratchet against each other, and because they only move easily in one direction the fibers migrate and tangle and cannot come apart again. The process is irreversible, which is also why a wool sweater that goes through a hot wash comes out as a small dense board.

Fur felts behave better than wool for hats, and the best are made from beaver and rabbit. To improve the felting, hatters treated the fur with a solution of mercuric nitrate, a process known as carroting for the orange stain it left. The fur felted faster and the hats were better.

The cost was borne by the workers. Mercury vapor rose from the hot, wet felting kettles in poorly ventilated workshops, and chronic exposure produces a condition with a recognizable set of symptoms: tremor severe enough to disrupt handwriting, and a cluster of psychological changes including extreme shyness, irritability and anxiety. It was common enough among hatters to become proverbial before it was understood medically, which is where the phrase comes from. It described an occupational disease, not an eccentricity.

Mercury use in American hat making was finally ended in 1941, by which point the industry was already in decline.

How to take part

• Feel the difference between a wool felt and a fur felt hat.
• Brush a felt hat counterclockwise and keep it out of direct heat.
• Felt something yourself with hot water, soap and a lot of agitation.
• Remember the phrase describes poisoned workers rather than eccentrics.