Seamless Intarsia

From Let Me Explaiknit.

The other method makes the joins where two of the color blocks meet, and is done by linking one yarn around the other as with flat intarsia, but with some changes because the yarn to wrap around isn't on the correct side yet. It has the disadvantage of having a slightly higher potential for getting tangled up in your work, and the advantage of being quite seamless; I definitely prefer this method. We'll continue using our smiley-face hat example; we'll need one strand each of yellow and blue, because in a seamless hat, there is one section of each color. On the first row which contains the motif, you will work with the blue strand to the right edge of the motif, then twist the yarns as usual and work the motif with the yellow strand. Now, having reached the left edge of the motif, you need to wrap the yellow yarn and blue yarn together, but the blue yarn is still back over on the right edge. What you're going to do is bring the blue yarn all the way around counterclockwise in a very long strand, and lay it over the yellow yarn; don't worry about the length of this very long strand, because we're going to take care of it in a minute. Once you've laid the blue yarn over the yellow, work counterclockwise with the yellow until you're back on the right edge of the motif. Drop the yellow strand inside the loop of blue yarn that you created in the previous step, and then use that blue strand to continue working counterclockwise through the entire blue section; pull out slack from where the end of the strand is caught by the yellow as needed. When you've completed the blue section and are at the left edge of the yellow motif, pull the blue strand taut, so there's no more slack in it and it's snug up against the yellow section. At this point, the blue strand is at the left edge of the motif, and the yellow strand is at the right edge. Draw the yellow strand loosely across the back of the yellow section, and lay it over the blue strand, and then work clockwise with the blue strand until you're back to the right edge of the motif. Drop the blue strand through the loop of yellow, work the yellow stitches clockwise, and then pull the yellow strand taut. As you can see, you're essentially working flat, with the turning point at the left edge of the motif (a brief note: if you have more than one motif, as when you put a design on the front and another design on the back of an item, the join point will end up at the left edge of the last-worked motif), but the left edge of the motif and the right edge of the background section are being linked together in exactly the same way that the other edges are; this gives you an effectively seamless tube. At the top of the motif, if the last row of the motif was counterclockwise, the yellow yarn will be at the right edge; do not draw it across the back, but simply do a YO with the blue yarn and resume working clockwise in rounds, using SSK to work that YO together with the stitch before it on the next round. If the last row of the motif was clockwise, slip the motif stitches in the counterclockwise direction to get back to the right edge of the motif, and then simply pick up the blue strand and resume working clockwise in rounds.