Okay, I know it's only been a couple of days since the last post; don't anybody keel over in shock. I spent most of this week in meetings that required minimal attention from me for large parts (though intense attention in the remainder), but in which I couldn't knit, websurf, check email, or read -- but I could, under the guise of "taking notes," write out the outlines for several posts. So we'll have a nice little spate of them while I work through this backlog, and then, I'm afraid it's likely to be back to normal around here. At least until the next round of meetings.
So, let's talk gauge! Now, I don't want to hear any panicking. So many knitters seem to consider gauge a bane, but they shouldn't; if you understand it, it's a really useful tool, leading to things such as sweaters which magically fit even after they've been through the first wash, and socks which stay up and actually fit the intended recipient and not some larger or smaller relation. So, let's talk about why you need to use it, and then we'll get into how to do it right.
Do you have to check gauge? No, not if you don't care if your items turn out the size they were intended to be. That's a bit of a flippant statement, but there's a little more to it than first appears. For some things, it really doesn't matter if they turn out exactly the intended size. It's hard for a scarf, and darn near impossible for a blanket, to be the wrong size; if you knit hats for charity, rather than for specific recipients, it's likely that your output will fit someone who will be happy to have it. For these things, you might do a tad of swatching to check that you like the resulting fabric, but you probably really can safely skip your gauge check, or at least do a cursory one on a minimal swatch instead of going all out. However, I think it's important that you first understand how gauge works and how to check it properly, so you can honestly evaluate the level of risk in skipping or skimping your gauge swatch, and avoid unpleasant surprises down the road.
Avoiding unpleasant surprises, after all, is what checking gauge is all about. It does take time to do a gauge swatch, and even more time to wash and block it. However, it takes quite a bit less time to do that than to knit an entire sweater only to find that "close enough" turns out to be a deal further off than you thought, and that the sweater intended for your 6-year-old is sized more for his 16-year-old cousin -- except that the latter has rather gotten over a taste for pullovers with dinosaurs.
There are two statements about gauge that I particularly hate to hear. One is the knitter insisting that she doesn't need to swatch, because she "always gets gauge," and the other is a knitter lamenting that she can't understand why her project doesn't fit, because after all, she used exactly the yarn and the needles called for in the project. There is no such thing as a knitter who always gets gauge, and even if you were one, how on Earth would you know that the pattern writer was? What if they're a loose knitter, and have gone down a size from the average -- if you follow them exactly, are you going to enjoy the results? No, of course you aren't. The needles specified in the pattern are a suggestion, a place to start your swatching, but that's all they are. It's the pattern gauge that you need to match, not the needles. If you know that you're about average, and the pattern gauge matches the ball-band gauge for your yarn, then starting with the recommended needles is probably a good place to begin, but that doesn't mean you don't need to check.
I'm going to set aside, for the moment, how to do a really accurate gauge swatch and get a good accurate measurement from it. Instead, I'm first going to assume that you've done a swatch and measured it accurately, and it's off. How do you use this information?
There are only two cases for how it can be off. The first case is where you have too many stitches in your 4" measurement area -- for example, it's supposed to be 20st/4", and it's 22. Too many stitches means that the individual stitches are too small -- you need to make them bigger, so you need a bigger needle. In this case, where you're about half a stitch per inch off, one needle size might do it; if you instead had 23 or 24 stitches, so you were off closer to a full stitch per inch, then skipping up two sizes would probably short-circuit some of the iteration.
The other case, probably obviously, is when you have too few stitches -- for example, you've only got 18, or 16, when you're supposed to have 20. Too few stitches means the individual stitches are too big -- you need to make them smaller, which means a smaller needle.
By the way, if you've got the idea that there is anything wrong or strange or odd about having to move several needle sizes to get gauge, get over it. There's not, and it's not in any way a reflection on your knitting abilities. Even if a variation seems unusual, it may reflect characteristics of the yarn you're using, or it may reflect characteristics of the pattern writer or test knitter. As an example, I am a fairly tight knitter; I have a friends who's a fairly loose one. We've knit socks from the same pattern, using the same yarn, but I used a needle that's four sizes bigger than the one she used -- and our socks came out the same size, because we both matched the pattern gauge, using the needles we personally needed to do that. And we know knitters who are looser than she is, and tighter than I am, who would have even more variability. There's nothing wrong with that. And to clear up a common misconception, our fabric is not any different -- hers is not more dense, mine is not more airy. Our fabric looks and feels exactly the same, because our stitches are exactly, precisely the same size: that's what matching gauge means. It's the size of the stitch that matters, not the size of the needle used to produce it.
One more comment on adjusting needle size: sometimes it can be tricky to match both stitch and row gauge, particularly if you're at a gauge that's open or dense for the yarn. When this is the case, work toward the appropriate stitch gauge first; when you've gotten there, try moving one more needle size to see what that does to your row gauge. Sometimes it'll change the row gauge without changing the stitch gauge appreciably; needle diameter affects row gauge more directly than stitch gauge, which is to a large part determined by the thickness of the yarn itself. If you still can't match both, generally it's easiest to match stitch gauge and adjust for row gauge; the exceptions would be things like sideways knit sweaters, where row gauge is the dominant measurement. We'll get to how you make those adjustments a couple of posts from now, so just hang tight on that one. If you're not too far off, it may be possible to block to the correct gauge, and you'll want to test that by blocking your swatch and seeing how it performs; we'll get to that in the very next post, when we talk about how to actually do the swatch.
And that's a good note on which to close: next up is the making and measurement of a fool-proof gauge swatch.