Pooling and flashing are terms used to refer to blobs or streaks of color that appear when variegated yarn is worked up. Usually I love to see yarn asserting its independence and getting all rambunctious on me, but as a yarn dyer I needed to better understand when pooling happens so I can control it.
My first foray into an experiencial investigation. When I was knitting Christmas socks, I calculated that it takes roughly an inch of yarn to make two stitches in stockinette. I have also used the rule of thumb that one armlength of yarn makes a row of sock knitting. My armlength is about 28", and my socks are usually 60 stitches around, so this jives pretty well.
My plan was to dye a skein of sock yarn with a 30" repeat, aiming to make a pattern repeat that would correspond to a row of sock knitting. Since it is hard to wind 420 yards of sock yarn into a 30" hank (the hank gets so fat that the yarn wound toward the end of the skein has a slightly longer diameter than the yarn would at the beginning of the skein), I settled for a 60" hank dyed in two pattern repeats. This is what my yarn looked like dyed up:
Each section of yarn is as close to 10 inches as I could get. I used tight ties between the colors to minimize bleeding, thinking that if there were little undyed sections in between then would serve to emphasize the boundaries between the colors.
(The green dye needed to sit for longer before being used - it separated at at the ends which is why you see turquoise there.)
If everything were perfect and consistent, I would end up with socks that had three vertical columns, one of each color. More likely, I thought, would be slow spirally indicating that my pattern repeat is slightly longer or shorter than one round of sock knitting.
I've only knitted up one sock so far but here's how it came out:
Since the rounds at the toe are shorter than the rounds for the body of the sock, the pooling pattern doesn't establish itself until the end of the toe when each round is 60 stitches.
(Details: base yarn is
Kraemer Jeannie sock yarn, dyes are
Jacquard acid dyes in sapphire, emerald, and silver gray, sock was knitted toe-up on 2.5mm/size US 1.5 needles at 60 stitches per round. The short-row heel was worked with yarn from the free end of the skein so the pooling pattern would not be disrupted.)
As I was working, spiraling to the left would indicate that my pattern repeat is slightly longer than a round of knitting; spiraling to the right would be caused by my pattern repeat being too short.
In this photo the sock is orientated upside-down so spiraling to the right means my pattern repeat was slightly too long. (Edited three months later - I just read a post on Ravelry that points out that spiraling looks the same upside-down, so what I wrote above is totally wrong. Spiraling to the right means that my pattern repeat was too short. If you look at my picture upside-down, the green part still travels from upper left to lower right. How embarrassing.)
<---My favorite part is right here when the spiraling reverses itself. When I winding my hank the chairs must have skidded closer together, shortening the diameter of the hank for the rest of the skein. I'm fairly certain the second sock will not do this.
Moral of the story: if you want to avoid pooling when making something in the round, you need to figure out how many inches of yarn are needed to make a complete round in your project. Also you need to measure the length of a pattern repeat in your yarn. This is the length of the hank the dyer wound the yarn in before dyeing. If your pattern repeat is the same as the length of yarn for a round, or if the pattern repeat length divides evenly into your one-round length, or if it's close, you will have pooling.
