Mulespun yarn is rather special, a type of woollen spun yarn that creates an especially airy, bouncy yarn. In the words of Bartlett Yarns, the last operational mule in the United States "The principle of the mule is to duplicate the motion of a handpspinner." The carded fibre is drawn out, as twist is put into it, and then that section is wound onto bobbins before the process begins again. In other spinning methods the fibre is constantly drawn and twisted, without the pause where the tension is relaxed.
There is no mule involved, I'll admit that when I first heard the name I pictured a mill powered by a mule walking in circles. It's called a spinning mule because when it was invented it was a cross between two other kinds of spinning machines. There aren't very many operating spinning mules, I believe there are only a couple left in North America, although historically they were more common in Europe (as far as I know most spinning equipment was imported to N. America from Europe and I suspect the mules were heavier and more costly although I am far from an expert on this history).
There is, however, one practically in my backyard, and anyone can visit it. A couple of months ago we went on a field trip to New Lanark,
a former cotton mill village and now a museum. The spinning mule is in
operation now spinning wool yarns that can be purchased in the museum
shop or ordered online.
There's also a hotel, youth hostel and holiday apartments if you ever
want to visit and the village is a fairly short drive from both
Edinburgh and Glasgow. I mentioned this briefly in the video but it's
also historically important because of its place in the history of
labour and education.
Sarah used New Lanark's Donegal Silk Tweed Dk for a Blank Canvas, which turned out beautifully.