Tonal yarns produced by kettle dyeing, space-dyeing or hand-painting are beautiful when seen in the skein. The wonderful subtleties of the color changes seem to catch the light and add an extra dimension to the yarn.
However, they are not always easy to use. One problem is that they can have quite a degree of variability, so that even within the same dye-lot one skein can be very different from another. This is, of course, part of their charm and character but it does mean that when you are making a pair of socks they can look quite mismatched.
Pooling of the colors and irregular zebra striping can be an additional issue, especially with small items such as socks. This pattern is designed to reduce these effects while still allowing the beauty of the yarns to shine through.