Hey BB,

When you "Block" a hat you form it into the shape you want. You use steam to warm up the fibers so that they will mold.

You can do it very simply by putting a cork in the spout of a tea kettle that has a tube sticking out. Then when steam starts to come out of the tube you use the steam to warm the section of the hat you want to shape and mold it with your hands. You can stretch the fabric. you can make sharp edges or nice rolled ones. It's really amazing the shapes you can get it to take.

We all used to do this with Cav Stetsons during my flying days. You know, think "I love the smell of Napalm in the morning".

Felt is wonderful to block. It will take almost any shape and as soon as the hat cools the shape will stay almost forever. My Akubra Fedora came totally unshaped. The brim was flat and the crown looked like "Hoss Cartright". Once I blocked it to the shape I like I have not had to re-shape it since. Just an annual touch-up where the brim may get a kink or flat spot. (unless of course you have to swim out to your get-away plane when the headhunters are chasing you like "Indie", then you get to re-block your hat from scratch).