All of us have, at some time or another, spun yarn that we are just not very happy with. It is too thick or too thin, too lumpy-bumpy, too smooth, even and uninteresting, or just not right for the intended use. Can it be fixed? And, if so, how?

The easiest way to “fix” a yarn that did not come out quite right for a project is to use it for a different project. This way has the advantage of giving us a good reason to buy more fibers and spin more yarn
but perhaps we love the color or the texture of this particular fiber or maybe it is an expensive exotic and buying more is simply not in the budget. There are still some things we can do to save the yarn or the fibers.

A too thin yarn can be fixed by adding more plies or by using it doubled.

A too smooth, uninteresting yarn can be used as the basis for creating a novelty yarn. For example, plying it with a sewing tread would change the look of the yarn without adding much bulk.

A too thick, boring, lumpy or otherwise unsuitable yarn may be unspun provided that the yarn has not been wet finished and is not fulled. Unspinning is a slow process so try just a little bit to start before deciding if the fiber is worth the time and effort. It is also not recommended for a plied yarn as the yarn would have to be unplied first.

The simplest, but most time consuming way of unspinning is to simply roll the yarn on your leg, rolling in the opposite direction of the twist in the yarn. Once the twist is out of a small section, pull the loose fibers out and set them aside. Repeat. A slightly faster method is to use a drop spindle to remove the twist. Use the “park and draft” method as the spindle will drop once the twist is out of the yarn and you also have to watch carefully for that point or the fibers will retwist in the opposite direction.

The fastest way is to use your wheel. With this method, you can respin the yarn to a finer grist at the same time as you unspin the too fat yarn.

Here's how it works:
Note that this assumes using an unfinished animal fiber singles yarn which was spun Z and that the goal is to spin this yarn to a finer grist.

Put a long leader onto the bobbin and tie the yarn to the leader.

Using your slowest ratio whorl and treadling slowly, spin S while holding the leader right above the point where it is tied to the yarn. When you can feel the twist building up behind the fingers of your forward hand, let just a bit of the twist into the Z spun singles. This removes the Z twist. Let the S twist in just a bit at a time until the fibers will start drafting back easily. Once you have the loose fibers drafted to the grist you want, clamp down with your back hand and let the S twist enter the fibers. Repeat.

Note that there is a point where the S twist being inserted meets the Z twist yarn. Always keep some loose fibers between these two twist points.