I hate sewing seams to assemble sweaters. If I wanted to sew, I’d crawl around on the floor cutting out fabric, then sit at the sewing machine.
Instead, I like to make sweaters in the round, whether bottom up or top down. When I make bottom-up seamless sweaters, I’m going to have to put stitches on holders at both underarms on the body and on each sleeve. If I don’t have enough needles of the correct size to leave all three pieces on needles until I can join them for the yoke, I put each sleeve and the body on holders while I work everything up to the underarm joining point.
Sometimes I have to try on things in work: socks, sleeves, sweater bodies, hats.
Some people use a length of the project yarn as the stitch holder. It’s not my favorite, because it can cause some (or a lot of) drag when you remove it.
That’s why I prefer satin ribbon. I use eighth-inch ribbon for worsted-weight yarn and sixteenth-inch for fingering weight. It slips through the stitches easily, with very little friction, and the best part is… Satin ribbon does not leave fuzzies behind.
Since ribbon is flexible, it’s going to minimize tugging on the stitches, especially if you have live stitches on each side of a group being held. Imagine a sweater front with the stitches at the bottom of the front neck on one of those extra-large safety-pin stitch-holder thingies. It will be a complete pain to work the sides of the neck up to the shoulders with that unfriendly thing poking you constantly. It’s going to distort the stitches on each side of it, and it may well poke itself into the yarn’s plies. Especially if you tend to shove your WIPs unceremoniously into your knitting bag, like I do.
I keep 18-inch lengths in my goodie bag for holding underarms stitches; 36-inch lengths for holding an entire sleeve, sock, or hat; and 6-foot lengths for sweater bodies. I put a dab of Fray Check on both sides of each cut end, since the ends will be pulled on quite a bit.
Once all the stitches are off the knitting needles and on the ribbon, I tie a bow to keep the stitches from sliding off. I leave lots of slack if I’m going to try on my WIP, and I do a not-too-tight, not-too-loose bow for everything else. And I can throw my WIP into my bag safely, knowing that I’m not stretching out stitches or damaging anything with unyielding safety pins on steroids.