I would guess that about 80% of the time, You Can Do That, although doing so might turn out to be expensive, awkward, or embarrassing. Or all three.
One of the biggest Can't Do That's around in Fiberland is the myth that you can't spin long fibers, such as silk and alpaca, on a charka. For those unfamilar with this device, it's basically a compact spinning wheel originally designed for spinning cotton. Closed, this size of this elegant machine is a bit smaller than a hard-backed book, hence its name book charka.
Spinners use charkas for other short fibers, such as cashmere and camel, but the First Law of Charkaness states that for longer fibers, You Can't Do That.
Having received this gorgeous cherrywood Bosworth charka as an early birthday gift, I dutifully spun the enclosed sample of mindnumbingly boring white cotton and then fooled around with some cashmere and camel. Okay, got the concept. Now on to the You Can't Do That fibers.
Out comes a lovely silk/merino batt from Corgi Hill Farms. These batts are not carded to homogeneity. Instead, the long, lush silk fibers are layered in between the beautifully dyed merino.
Contrary to expert opinions, not only can silk be spun on a charka, it spins beautifully with nary a blob.The stuff was just meant for long draw. It spins thick, it spins thin, it spins any way you like your yarn.
Here are some samples--medium, thin, and really thin.
And while we are busting myths, we might as well explode the Second Law of Charkaness: You Can't Spin Thick Yarn on a Charka. Sure you can, and here are some thicker samples to prove it:
Of course, the spindles on the Bosworth are small and delicate, so spinning yarn of this weight would fill them up in a few minutes. However, I have a Babe charka too, which sports a spindle fashioned from a nice, big knitting needle (courtesy of a fortuitous swap with Janice in Georgia). That spindle can hold almost as much as a clunker drop spindle. So there.
I figured I was on a roll, so I pulled out a one-ounce spindle and spun some gossamer laceweight from the batt. Current opinion is that you can't spin gossamer-weight on a spindle that heavy. I went up to the heaviest weight spindle I own, a 1.2 ouncer. And spun gossamer on that too.
All this, by the way, was accomplished in my round kitchen, which, when we requested this eccentric design from a herd of architects and builders, were told: "You Can't Do That."