I finished this sweater up this past Saturday. It actually dried quickly for a DK weight sweater, but since it has dried I have been pondering the mysteries of gauge. The sweater actually fits me perfectly, but I really think I just got lucky this time. When I knit my gauge swatch I thought I was good to go.

When I tried on the sweater I realized that the ease was not as large as I was expecting based on the pattern size. It meant that the sweater actually fit me better, and with the merino/silk blend, it feels wonderful to wear. So I decided to check the gauge of the finished sweater to see how it changed, as well as going back and re-checking the swatch. While it was lying around the swatch actually tightened up a bit, to about 21.5 stitches and 30 rows in a four inch square. On the sweater itself, the body gauge ended up at 22 stitches and 26 rows, while the sleeve gauge ended up at 22.5 stitches and 27 rows. I wasn’t surprised that the sleeve gauge tightened up, as I do tend to knit tighter on the smaller circular needles (in this case 16” circulars). The pattern gauge is 20 stitches and 28 rows in a four inch square. I knit the sweater on US 6 (4.0 mm) needles, and I like the fabric, it is not dense, nor is it loose, and it still has nice drape - the silk helps with that, but so does the superwash merino, as superwashing wool pretty much denatures it and removes any woolly-ness. Most of my experience to date has been with superwash wool, as it wasn’t until I started spinning that I really started getting in to the wonder that is non-superwash wool, so this discussion is based upon my experience with superwash wool
Now, I don’t really trust pattern gauges that much anymore. I typically will knit a swatch to get a fabric that I like, but I don’t obsess about completely matching gauge. I can do the math to make the adjustments. Over the years I have decided that there is an optimal gauge for any yarn when knit in stockinette that gives a nice fabric, not too dense, not too loose, with a stitch to row ratio somewhere around 0.75. How did I get to that number? It is simply based on the fact that when picking up stitches along the edge of knitting the typical rule of thumb is three stitches for every four rows. I will often check this ratio when looking at a pattern, and if the gauge stated for stockinette varies too far from this ratio I may not trust the stated gauge (especially if it is lower). So let’s look at the ratios of the pattern gauge as compared to the gauge that I ended up with. The stitch to row ratio of the pattern gauge is 20/28 = 0.714. For the body, my stitch to row ratio is 22/26 = 0.846 and for the sleeves it is 22.5/27 = 0.833. So both are on the higher end, but the fabric is nice and definitely not too dense. Now it should be noted that if I had to pick stitches up along the edge of knitting with this gauge, I would pick up 4 stitches for every 5 rows, as this would give me a ratio of 0.8. Based upon the resulting gauge of the finished project I doubt that I could have matched the pattern gauge even if I had tried, at least not with this yarn.
The needle size that I will pick for any given yarn is based on matching the diameter of the needle to the width of two strands of the yarn laid side by side. I base this on the structure of knitted fabric and the way the loops of the stitches lay. Picking a needle size based upon the size of the yarn strand ensures that the stitches will nestle nicely and will not be loose. If there is extra yarn in the loop the knitting will lack structure and will become easily misshapen. Loose knitting also makes measuring a gauge swatch problematic, as you can stretch it vertically or horizontal to match a gauge, but once you turn that into a garment, gravity is going to take control with potentially disastrous results. This is why I also take issue with anyone who states that matching stitch gauge is more important than matching row gauge. Both are important, because they are intimately connected as it is all a continuous strand of yarn, so you cannot separate them in your consideration of your knitted fabric and the resulting gauge. Another interesting benefit that I have found with my method of picking a needle size is that I don’t have the problem of rowing out when knitting flat.
There are many factors that go into knitted fabric and the resulting gauge, and not all of them can be taken into account by a gauge swatch because size does matter, and I don’t think that you can really make a gauge swatch large enough to fully explore all of the factors. I have had gauge swatches that were truthful, and some that were not. In a pattern that is knit vertically, row gauge can be problematic because of gravity. I also think that superwash merino, especially when blended with silk, is going to stretch vertically. Superwash wool lacks the spring that non-superwash wool has, and the stitches will slide past each other instead of clinging to their neighbors, so the row gauge should be expected to change, which will also change the stitch gauge because they are connected. How the yarn is spun will also affect the resulting gauge of the finished project, a more tightly spun and plied yarn is not going to stretch as much as a more loosely spun and plied yarn. The sweaters that I have knit out of sock yarn definitely do not stretch as much, and their gauge swatches were truthful. So, definitely a learning experience here, and I’m very glad that it all worked out and that the sweaters fits me.
Pattern: Adult Acorn Sweater by Kalley Reedy
Yarn: Sundara Yarn Extra Fine DK Silky Merino
Needle: US 6 (4.0 mm) and US 4 (3.5 mm, for the ribbing)