HATTERS (hatmakers) made most hats from felt, although some hats were made from skins of animals or from other materials. Felt was made by matting wool or the undercoat of animal pelts. The soft underfur from a beaver pelt made the best felt for a hat. This would be plucked or combed from the pelt. Often hatmaking was a family business, and the fur plucking was done by the children of the family. The loose fur was weighed to be sure that there was the proper amount to make a hat. Each pile of fur would become a single hat.
The fur was placed onto a hurl, which was a table enclosed on three sides. Suspended from the ceiling was a giant rectangular strung bow. Plucking the sheepgut string of this bow caused vibrations which helped the individual hairs to be more evenly distributed as they would cling and mat together. The matted piles of fur were patted into round-topped pyramids, and then flattened with a slatted wooden hatter's basket. This well-matted pile of fur was called a batt.
Batts, separated by wet linen towels, were stacked on top of each other. A second craftsperson kneaded pairs of these batts. The kneading formed the batts into cone-shaped hoods that would become the hat's body. The hoods were boiled for six to eight hours. This fulling process caused the hoods to shrink and thicken. Next the hoods were sent to the battery.
The battery was a kettle in a brick enclosure. A sloping wooden plank was built around the top of the bricks. The kettle contained a mild acid solution that was kept boiling. The hoods were repeatedly dipped into the kettle, then rolled and planked. Planking was done by beating the hood with a club. During this procedure knotted hairs and impurities were removed from the hood. If needed, more fur was patted onto the body with a wet brush to fill in any thin spots.
The hood then had to be blocked to shape it. Blocks were molds of different sizes and shapes. Each one was attached to a circular bottom board. This board represented the brim of the hat; the block was the crown. The master hatter would put the soaking wet hood onto the block. Using a runner-down stick, he stretched it over the block. He flattened the brim onto the board and removed any wrinkles from it. The shaped hat was popped into a slightly warmed oven. It was dried over night with the rest of the hats made that day. The hats were removed in the morning by the finisher.
The finisher trimmed each hat's brim. The surfaces were smoothed with a pumice stone. The finisher ironed the hats and paddled them in order to raise the nap. He shaved off any wild hairs that refused to lay properly, and brushed the nap in one direction. A leather headband was stitched to the inside. Decorations such as crown ribbons and edge bindings were added. Brims that were to be cocked were steamed, rolled upward, and taped while the hat dried on the block.
As with all crafts, the hatter varied his technique according to the fur or wool he was using. Felt made from sheep's wool did not hold together as well as that made from the fine underfur of a beaver pelt, so wool hats often had glue or varnish added during the felting process. Cheaper hats were rolled in cloth during planking so they wouldn't fall apart.
It usually took seven years of apprenticeship to learn all the steps of making a hat, and to become proficient in styling and craftsmanship.

Information from the book
Colonial American Craftspeople
by Bernardine S. Stevens

INTERNET Adaptation
by Sandra S. Bray