Ribbing w/ #5 US needles, rest with #4 US
I first tried out knittig with #4 needles when finishing a pair that my mother had started (for herself) for a friend whose feet were my mother's size. That proved I could now (being more experienced) see the stitches well enough to make socks like that. I made two more pair using first my mother's old acrylic yarn and then one in wool. Then, on the Birthday Socks this spring, I knit one section with size 4s...the stockinette between the ribbed cuff and the heel flap. I did one with the same stitch count as number 5s (a little snugger than I like) and added two stitches (actually, did not reduce 4 st. between ribbing and stockinette, as I usually do) to that section, which produced the fit I wanted. With #4s, I get 7 st./inch in stockinette and 10 rows to the inch, instead of 8. Since the ribbed cuff doesn't wear out fast, I knit the ribbing of the current test pair (royal blue) on #5s, switching to #4s at the ankle, and using the stitch count I'd found worked on the Birthday socks. I left the "front" of the sock with the extra stitches, knitting the heel flap with the familiar number, to see how I liked it. Heel flap position on my heel...the heel flap difference in "wrap around" is about half an inch...a quarter inch on each side. Next pair I do on #4s, I'll do the reverse, and see if I like the wider heel flap better. I will need to wear the socks and walk some miles on the land in them to see if the narrower heel flap will work for me, and if the same stitch count in the middle--the "cup" for the heel--feels right.
Figuring the gusset decreases took real consideration. First, beause of the difference in row gauge, there were more stitches to be picked up. I have both a high instep and a high arch...a very long circumference around the back of my heel pad and the top of the instep, and then a steep decline in circumference as the arch rises fast from the heel. On #5 needles, I've been decreasing two rows, decrease one, to ensure no extra fabric under the arch. On the #4s, I checked the fit every row, and found that I needed to combine both that rate of decrease and the 1:1 ratio usually suggested. After the last non-decrease row, I could decrease that one extra stitch off the top needles, back to even stitches on each needle. There's another decrease (below the "bump" on the top of the foot) coming up soon. And then the work to get the toe fit right for L and R feet.
Stitch counts compared so far: Size 5 US needles Size 4 US needles
Ribbed cuff 60
Heel flap 28
Instep needles 28 30
After gusset 54 -->52 56 -->? (not there yet)
Using a smaller needle puts more wool in the project--denser fabric that should last longer--but also uses up yarn faster (of course) and take longer to knit for a slow knitter like me. Every stitch takes the same amount of time, with either size needle, and puts the same wear and tear on my finger joints...so more stitches per sock means more wear on my joints. Also, though I can still see stitches well enough, increasing vision problems, especially for close work, mean that eyestrain is more using #4s. I plan to use them for mitts, but am discovering just how much harder it is to work with, essentially, one eye (the one that still has a cataract. The other eye has a focal point problem.)
I will use this pair, when it's done, to figure out whether it's worth the extra yarn and effort for the amount of durability gained. This pair will be charted (number of days worn) and I will wear it more frequently, probably once a week, to get the answer faster. If I can finish a pair of socks done in #4 needles in a month (about what it takes me now with #5s) I may start using #4s for some of the socks.