My questions are:
1. Why is it recommeded to use smaller needles for ribbing than what is used for the body of a piece?
2. What is the recommended difference in needle sizes? By what do all of you swear? I've seen patterns that instruct to use needles that are one size different (say US 7/4.5 mm for ribbing, US 8/5 mm for body), and some patterns that say to use needles that are two sizes different (US 6/4.25 mm for ribbing, US 8/5 mm for body).
I have some projects with ribbing that I have put off for some time, and I won't get back to them untill I get other people's opinions on this matter.
My theory as to why it is recommended to use smaller needles for ribbing is that the smaller needles cause the rib stitches to bunch close together, instead of leaving the stitch open if worked with a single size of needles.
Case in point-
I have a plain black superwash wool cardigan in the works, made up with US 8/5 mm needles. A small sample of the details: for the fronts the ribbing has 44 stitches , and increase by 6 stitches (for a total of 50 stitches) for the stockingnette stitch body. I don't mind the way the ribbing looks, as the stitches are beautiful and well-defined, so I may not have to redo it with smaller needles.
(On my laptop at home the stitches in the photographs are visible, but the photographs are dark on this computer that I'm using at the public library. In order to see them, you'll either have to adjust your moniter's brightness or I can lighten up my images.)
Some lighter images of the ribbing.
Unfortunately, however, I have a skull argyle sweater vest in progress that uses the same amount of stitches for the ribbing as well as most of the body, and the ribbing is just unsightly! I think this might be because I used acrylic yarn. Acrylic yarn (in my experience) doesn't seem to be able to handle 1X1 rib, though it's fine with 2X2 rib
Ugly, open rib stitches
Stitch detail (don't stare too long, you might have to get eye transplants)
Another detail shot
Stitch detail (slightly stretched)
I even worked up a swatch using the same yarn as the vest (Bernat Satin) in a different color to see if the stitches would look better if the piece were made with less stitches for the ribbing compared to the body, as with the black cardigan. The results:
Stitch detail (slightly streched)
Not bad, compared to the argyle sweater with the same amount of stitches for the ribbing and the body. But as one can see, the rib stitches are open. I thinking using smaller needles would help "close" them up.
So to recap, I think smaller needles are used to "close up" the gaps in the rib stitches, since they seem to open when another stitch (like stockingnette stitch) is introduced. But the "openness" problem seems to be affected by fiber as well; wool seems to look fine without having to change needles. When worked in one needles size, acrylic looks terrible with 1X1 rib, but decent with 2X2 rib. This is 2X2 ribbing for an acrylic vest.
So what are your ribbing experiences, tips, and recommended readings (if any)? I look forward to hearing from a lot of people!