This is easily one of our most asked questions- usually right after we've asked if the customer wants their yarn wound! It turns out, there are a couple of reasons why...
First, a quick vocabulary lesson... Unwound yarn is typically called a "hank." Commercially wound yarn that is ready to go and doesn't need to be wound is usually a "ball." And wound yarn by us? A "cake!"
The biggest reason yarn often comes in hanks is that it travels much more reliably that way. Wound balls tend to snag, fall apart, and generally become tangled knots.
Also, unwound yarn is much better for the fiber for storage. When yarn is wound, it puts tension on the fiber which is fine for a while, but long-term it will slowly stretch the yarn. If you don't think you will get to the project for a few years, do yourself and your yarn a favor and hold off on winding!
Also importantly, it's often to see the color of yarn when it is unwound! Especially if it is hand-dyed, kettle-dyed, variegated, or speckled, you can unwind the skein and see it in all of its glory to help pick the perfect one for your project.
Finally, if the yarn is a hand-dyed yarn, cost factors in. Winding the hank into a ball after it is dyed is just one more step a dyer has to do and therefore pass the cost on to the customer. Leaving it as dyed in the skein keeps costs down for everyone!
THE BOTTOM LINE
While it's a little more work, leaving yarn unwound in a hank is better for it, and usually better for the dyer and you, too!