This subject has come up lately, both among milliners I know and in trying to explain it to customers. So here's the basic info on the material used to make felt hats.
Note: This is just about felt for blocked hats, not fabric or straws for other types of hats. And I know nothing about hand-felting or wet-felting. This is about the unshaped felts currently available from millinery suppliers (so it doesn't cover vintage felts, either). Fur felt — in any of its various finishes — is what you'll see used most often in high-end felt hats.
Wool — The least expensive option. Has a somewhat nubbly, uneven texture. Not as warm or as sturdy as fur felt. More animal-friendly. Decent color options.
Plain fur felt — More (2-4x) expensive than wool, but a much nicer quality. Holds its shape well and is quite warm. Made of rabbit fur (or occasionally rabbit and hare). Plain fur felt is dense and smooth. Lots of color options. Sometimes available in thicker/heavy weight or thin/tissue weight or with printed or embossed patterns.
Salome fur felt — A more rustic style fur felt with a kind of heathered color and occasional longer, spiky hairs. Dense and warm. Limited color options.
Velour fur felt — Also known as peachbloom. A small amount more expensive than plain fur felt. Dense, but with a spongey, velvety texture on top. (This finish can be on both sides or on one side only.) Quite warm. Lots of color options.
Long-hair fur felt — Also known as "beaver"-finish, "beaver"-style, long-nap or melousine. Not actually made from beaver fur. It is made of rabbit fur. Has long hairs on top of a dense felt. (The long hairs can be on both sides or on one side only.) The long hairs add a luxurious sheen if brushed/polished smooth. Alternately can be mussed up for a more casual style. More expensive than plain or velour fur felt. Quite warm. Good color options. Also available printed with animal patterns (leopard, cheetah, etc.) for additional cost.
Suede fur felt — A sueded finish (not actually made of leather or suede). More expensive than plain/velour felt. Dense with a luxurious finish that looks like velvet or fine suede. Quite warm. Limited color options (generally dark/neutral).
Cashmere — Made from hairs from a cashmere goat. A soft, spongey texture throughout. Very warm. Animal-friendly. Much more expensive than fur felt. Limited color options.
Beaver felt — The top of the line. This is what the most expensive, luxurious hats are made out of. Especially popular for men's fedoras. Actually made from beaver fur (though there is a middle ground of felts that are a blend of beaver and rabbit or hare). The felt is thinner than fur felts and yet warmer and more supple. Holds its shape better than fur felt and is more naturally water-resistant. Dense and smooth. Limited color options. Expect a beaver felt hat to set you back at least $300 (and often more).
|L-R: wool felt, plain fur felt, salome fur felt, velour fur felt, long-hair fur felt, cashmere felt|