Most knitting and crochet patterns call for multiple skeins of yarn that have to be joined. If you are using a sticky or fuzzy yarn, such as Shetland wool or a mohair yarn, there are many ways to join these yarns without knots. Even super-wash wool and wool blends can be joined without knots. However, some yarns benefit from knots; these yarns are made primarily or entirely from smooth silk or synthetic fibers. Slick fibers such as these benefit from knots, and a secure, discretely placed knot will not affect the integrity of the design.
Tie a Slip Knot
Hold the tail, or end, of one ball of yarn in your left hand and the working yarn, in your right hand.
Loop the working yarn down over the back, under, and up the front of your left index finger.
Drop the working yarn. Reach through the loop, front to back, with the thumb and forefinger of your right hand, a knitting needle or crochet hook. Catch the working yarn and pull it through the loop, back to front.
Place the loop of yarn on a hook or needle if you've used your thumb and forefinger. Pull the tail of the yarn so the knot is small but not tight. Pull the working yarn so the loop of yarn is snug on the hook or needle.
Use this knot when casting on in your preferred method to begin a project.
Tie a Square Knot
Hold the tail of the finished ball of yarn, which you have made into your work-in-progress, in your right hand and the tail of the new ball of yarn in your left.
Lay the right end over the left end. Pass that right end back over the left end, under it and back up. It is now the left end. Lay this left end over the right end, pass it back over, under and up so it is now at the right end once more.
Hold the tail of the new ball with the working end in your left hand, and the tail of the old ball of yarn, which is now your work in progress, in your right hand. Pull, gently but firmly, until the knot is as small and as tight as possible.
Use this knot to join yarns while making a garment. Plan your knitting so that you are able to knot your yarn at a side seam or edge. This allows you to use the ends as sewing material for the seams, or hide them in the treatment you use to finish the edges, such as crochet trim or a knitted-on button band.
If you are knitting a garment in the round to the underarms, knit to the middle of the garment where the underarm seam would be, and join yarns in a square knot. Leave tails several inches long. Pick out the last two inches of your knitting, and reknit those stitches with the tail of the old yarn held double with the old working yarn. There should be enough of the tail dangling so that it will be inside the garment, or about one-half inch. Knit to the knot with the old yarn, and then knit the next two inches with the new working yarn held double with its tail. Drop the old yarn inside the garment, and continue knitting with the new working yarn only.