How to Join New Yarn or A New Ball in Knitting
Joining a new color of yarn (for example when knitting stripes) is the same method as joining a new ball or skein of an existing color when the first ball or skein has run out.
To prevent unsightly knots, join new yarn at the beginning of a row wherever possible. To make a perfect join at the end of a row, simply drop the old yarn and start the next row with the new yarn. If this is difficult to do, you may knot the new yarn and old yarn together temporarily while you knit.
Untie the knot and securely weave in the yarn ends at finishing. Leaving the yarn ends knotted leaves an unsightly bulge in your yarn and is not a secure way to leave the ends.
If it is impossible to avoid joining new yarn in the middle of a row, try one of these methods.
Drop the old yarn when at least 6" remain. Start work with the new yarn, leaving a 6" end. After a few more inches of knitting have been completed, individually thread the ends through a yarn needle and weave them back and forth for a few inches to secure.
Another method to join yarn is the splice method. When ast least 6" of the old yarn remains, untwist the plies of yarn. Untwist the plies of 4" of the new yarn and retwist them with the untwisted plies of the old yarn. Work with this doubled length until you are working entirely with the new yarn.
When working with thinner yarns, it may not be necessary to unply the yarns and retwist them. When at least 6" of the old yarn remains, simply pick up the new yarn and work with both yarns until the old yarn runs out. When working the next row, work these doubled stitches as one.