This is not actually a knitting post but close enough--a trick with loose wool. The thing with Uggs, heck, with all shearling boots, is that as time goes by, they start to wear out. First, the wool inside gets beaten down. Then, the leather tends to stretch with wear. So here's a (super) simple trick to refresh the innards of a well loved pair, and at the same time, tighten the fit to like-new.
1) obtain some loose wool--the kind of locks prepared for spinners (washed and combed) are perfect. However, pretty much any combed loose wool with vegetable matter and oils removed will do.
2. Slip some of this loose wool into your boots in small handfuls, trying to keep the strands of the fibers oriented in the the same direction. Insert your foot every handful or two, to test the fit, then keep going until things feel snug but not suffocating. Put the wool more around the edges of the foot, and don't put as much under the foot as you think--too much loose wool under the sole tends to clump up and get hard to walk on. As you walk around, the wool inside will mold to your foot.
It is best to wear your Uggs barefoot with this trick, or the loose wool will stick to your socks and make a mess. If you must wear socks, wear thin light-colored smooth cotton ones, *not* woolen.
As to the exactly best kind of wool to use, my own method has not been very scientific--I just grab a small bag of loose wool at a farmer's market whenever it comes up for sale, so I can't tell you what kinds are best. It does seem, however, that different batches of stuffing-wool last for different amounts of time. Perhaps someone more knowledgeable will speak up in the comments as to what would be a specific kind of wool to look for?
At any rate, when this new wool has become too trodden down--overly felted and worn, its easily removed and replaced with fresh.
Neat, huh? Not a new idea, though--this is actually a trick from the Middle Ages.
This is how folks kept their feet dry and warm in all manner of clunky footwear--wooden shoes and heavy boots. This is also how the fit was adjusted on the coarsely-sized footwear then made. Wool was used if available, but really poor folks used straw (ouch!) or moss.
--TK