I knew Donald would jump in and reply with his usual great information! Pig's wool is a VERY classic English tying material. Look at many of the old writings from Thomas Barker, James Chetham and the like and many of the patterns call for "hogs down". Chetham lists his must haves for fly tying and indicates that hogs down can be " . . . gotten from butchers, or others and is combed from the roots of the hair of the hog . . . it can be dyed any colour you judge convenient, and it's excellent because it both shines well and is stiff, proper for the water, and is lively."

They were using is for dry flies as well. And that's back as far as the late 1600's and into the 1900's.

I guess it's been around for a while!

The skin cures very much like deer or elk. Gets very hard if dried and cured.

Joe