Long before I became a knitter, I was sewing my own clothes. Here's a dress I just finished made in a two-way stretch fabric. (Bear with me. This does pertain to knitting.)

It looks much better on me than on the hanger. The wrapped bodice and A-line skirt give it a very sexy shape on the body. I look forward to wearing it to the ballet when the new season starts next month. But for knitting purposes, I wanted to talk about this fabric and some of the finishing techniques we use in sewing knitted fabrics. The fabric is basically stockinette at a super-fine gauge, cotton with a dash of lycra. It would be appropriate for swimsuits or dance costumes because of the high degree of stretch on both the horizontal and vertical grains.
So, knitters know what happens with this kind of fabric along the edges. Curls like whoa damn. This particular pattern didn't call for facings (which would have added bulk and might have interfered with the way the fabric moves) but for rolled hems at cuff and bodice edges. But we know from knitting that these curly edges can be made to lay flat by adding an edge with a slightly different pattern. So I decided to use cross-grain binding pieces at these edges to make them lay smooth. Here's the bodice. You can easily see from the print that the piece was cut at a ninety degree angle to the bodice. This isn't the true cross-grain because the bodice pieces are angled, but they're at right angles. It works.

And the cuffs, also on the cross-grain, but on the true cross-grain, meaning that the binding pieces are cut with the grain running horizontally. (This is the opposite of the way pattern pieces are usually cut, on the vertical grain. Weavers will be thinking about warp and weft right now.)

See how nice and flat those edges are? No rolling at all. (By contrast, the skirt hem, which is a narrow rolled hem, tends to flip up along the stitching line because it doesn't have a special finish. Which might be changing in the foreseeable future, because I don't like it.)
Knitwear designers incorporate details like this into sweaters for the same purpose. But one thing they don't always do is stabilize the shoulder and neck edges during finishing. I think this is an important finishing detail with knitted fabrics, which can stretch out of shape along the shoulder and collars if we don't stabilize them. Here, I used a bit of seam tape (purchased at the fabric store in the notions section near buttons and zippers) to stabilize the shoulder seam. (I had to flip the seams inside out to show you -- so it looks funny, but you can see from the first picture at the top of the post that these seams lay very flat and smooth.)

Well-made ready-to-wear will also have this stabilization along the neck and shoulder seams. Here's a fleece jacket I bought in the late 90s from Lane Bryant, well constructed and still perfectly suitable for wear to the gym. They used a grosgrain ribbon instead of seam tape. Either will do -- the main thing is to find something that doesn't stretch.

These kinds of finishing details are becoming increasingly rare in ready-to-wear as manufacturers cut corners. One of the benefits of learning to knit and sew is that we know what to look for in quality garments. I doubt I paid more than ten or twenty bucks for this fleece jacket, but because it was made well in the first place, it has held up beautifully to hard wear in the gym. There's some pilling on the fabric's wrong side, which is the only side of wear so far. Without the stabilization ribbon, though, I'm sure this would now be stretched out and shapeless and ill-fitting now. I have knitted shirts far younger that are ready for the rag bag because they weren't as well-constructed.
Moral of this story: Knitters, stabilize your shoulder and back neck seams, and your beautiful garments will last longer.