Needle Felted Celebrities By Kay Petal

From the mid-17th to the mid-20th centuries, a process called "carroting" was used in the manufacture of good quality felt for making men's hats. Beaver, rabbit or hare skins were treated with a dilute solution of the mercury compound mercuric nitrate. The skins were dried in an oven where the thin fur at the sides went orange - carrot color. Pelts were stretched over a bar in a cutting machine and the skin sliced off in thin shreds, the fleece coming away entirely. The fur was blown onto a cone-shaped colander, treated with hot water to consolidate it, the cone peeled off and passed through wet rollers to cause the fur to felt. These 'hoods' were then dyed and blocked to make hats. This toxic solution and the vapors it produced resulted in widespread cases of mercury poisoning among hatters. The United States Public Health Service banned the use of mercury in the felt industry in December 1941.
Knitted woollen garments which shrink in a hot machine wash can be said to have felted but, more accurately, they have been "fulled". Felting differs from fulling in the sense that fulling is done to fabric whereas felting is done to fibres that are not in fabric form. Modern fulling is an example of how the fibres bond together when combined with the movement of the washing machine, the heat of the water, and the addition of soap.