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Friday Funnies: On Swatching

“[Swatches are] as honest as ex-husbands with new girlfriends and hair transplants who owe you child support…. on a good day.”

The Yarn Harlot

Knitting Math

Yesterday I posted about ambitious knitting. Which got me thinking about why I knit. If you enjoy a craft, it’s usually because you enjoy both the act of doing it as well as the finished product when you’re done. Many knitters are perfectly happy knitting and wearing garter stitch scarves. There’s clearly no obligation to pursue ambitious knitting projects, so why do I?

For one thing, I like wearing socks and sweaters and lace shawls, so it makes sense that I’d want to make those sorts of things. And for another… well, I suppose I view knitting as an intellectual exercise as much as a craft. I’ve always loved puzzles and logic problems. Heck, most of my undergraduate & graduate studies were spent problem-solving (mathematics, operations research, and computer science). B.C. (before children), I designed computer software and websites. I guess knitting was a logical progression!

Knitting presents an interesting puzzle for me… how do you manipulate yarn to make complex lace patterns or to fit the curves of a human body? The mathematician in me loves problems like that. And the knitter in me appreciates that knitted fabric is nice and stretchy, so dipping into triple integral calculus is purely optional.

I always have to stifle a chuckle when I hear knitters complain about “knitting math.” To me, that’s some of the fun of it! Yes, I do realize that this is not a common view. 🙂

Case in point: My Lanesplitter Skirt. The original pattern calls for casting on in a corner, increasing on both edges to make a large triangle. When the right side is the length you want the skirt to be, you start decreasing on the right side and continue increasing on the left side. When the left side is as wide as you want the skirt to be, you decrease on both sides back to a point, then seam up the short side to form a tube. Very clever pattern.

Before I decided to make one of my own, I spent some time reading the project pages on Ravelry (okay, not all 1,457 of them, but enough of them to get an idea about the pattern). Many people commented that they didn’t like the way the stripe colors didn’t match up at the seam, so they suggested that you start with a provisional cast-on, work only the straight section (decreasing at the start of every right-side row and increasing at the end), and then graft the skirt closed at the end, so you get a seamless tube. This sounded brilliant to me!

But how to determine the correct size? I reasoned that we’re knitting a parallelogram (the top and bottom of the skirt will be the same number of rows and thus should be the same size once blocked, and the sides of the seam to be grafted will be the same length). The original pattern called for increasing equally on both sides of the work, so you should end up with a triangle with roughly equal-length sides. This means that you have a 45-45-90-degree triangle. (Sorry if that flashback to geometry class was painful for you!) Which means that the hypotenuse of the triangle is the length of one side times the square root of two (approximately 1.414). So if I want my finished skirt to be 19.5″ long, I need to cast on enough stitches to make approximately 27.6″ of knitting (19.5 times 1.414). My gauge (after washing) was 19.5 stitches per 4 inches, so I needed to cast on 27.6″ times 19.5 stitches divided by 4″ = 134 stitches. I expected the weight of the fabric to cause the fabric of the finished skirt to stretch a bit more than my gauge swatch, so I rounded down to 130 stitches.

I just measured my skirt again, and found that it’s about 18.5″ from one edge to the other. It hasn’t been blocked yet, so with blocking and the way I anticipate that the fabric will stretch lengthwise when I wear it, my skirt should come in right about 19.5″ when it’s done. Yay for knitting math!

How do you feel about knitting math? Do you embrace it or avoid it?


More on swatching…

We’re still recovering from illness around here, so no sadly, new knitting to report here. But I just read a great post by Kate Atherley (Wise Hilda Knits) on the difference that a even a quarter of a stitch can can make in your gauge.

So now I’m wondering if those tiny fraction-of-a-stitch-off measuring errors (even over a 4-inch swatch that you’ve oh-so-carefully measured) might contribute to the perceived inaccuracies of swatches. What do you think?

Sometimes swatches lie

Swatching seems to be a popular topic right now! After I wrote my last post on swatching, I saw this post on the WEBS blog. They suggest putting eyelets in your swatch to indicate the size needle that you used in the swatch, in case you forget by the time you’re ready to actually start the project. This is a great idea, especially if you have another large project that you need to get out of the way before you can start the new project. (I usually use purl bumps to do this, as they don’t seem to distort my gauge as much as the eyelets do.)

So once you’ve done your swatch, figured out what needle gives you the fabric you like best and cast on the project, you’re good to go, right? Well, not always. You see, sometimes swatches lie. They don’t really mean to, they just can’t help it!

Now, I’m assuming that you made and measured your swatch correctly:

  • You used the same needles that you’re going to use for the project. Not the same size needles, the same exact needles. I get very different gauges between the same size wood and metal needles, and I have even noticed differences in gauge between aluminum and nickel-plated metal needles.
  • You made your swatch in the same way that you plan to knit the finished item (i.e., if you’re knitting your sweater in the round, you knit your swatch in the round as well). TECHknitting has an excellent post on circular swatching.
  • You used the same stitch pattern that you will use for the actual pattern. If you’re making a heavily cabled sweater but worked your gauge swatch in stockinette, your finished sweater may fit your cat. 🙂 Usually the pattern will state the gauge and say “in stockinette stitch” or “in pattern stitch,” so you can calculate your gauge accordingly.
  • You made your swatch large enough. Ideally you want your swatch to measure at least 6″ square. This gives you at least a one-inch margin around your 4″ measurements.
  • You measured your swatch correctly. You want to measure the number of rows or stitches over 4″, not over 1 or 2″. Something that looks like 5 stitches per inch could be actually 19 or 21 stitches over 4″, which may not seem like a big difference but could translate to a 4″ (or more!) difference in the size of your sweater!!
  • You measured away from the edges of your swatch. Cast on and bound off edges often have a different tension than the rest of your stitches. If you used a different stitch pattern along the edges to keep your swatch from curling, this will likely alter your gauge near those edges.
  • You washed your swatch. Some yarns— like superwash wools or yarns with silk in them— will grow when washed. A lot. Wouldn’t you rather know that now, before you knit the whole sweater, bound off, knit the button bands and sewed on the buttons?

But what if you did all that, and still realize that your gauge is off once you start knitting? How could that happen? Well, it might be you. If you’ve been knitting socks at a tight gauge and then start a sweater in chunky wool, you might unconsciously strive for a tighter gauge. Maybe you knit your swatch while relaxing in front of the tv, but now you’re knitting on your lunch break, in the middle of a stressful project at work.

Or maybe— and I think this is what happened with my Lanesplitter— you get a different gauge when knitting a small swatch than you do when you’re knitting a project that involves scooting a lot of stitches around your needles. The gauge on my swatch was 20 stitches per 4 inches but once I cast on my 130 stitches and started knitting, I found my gauge was 19.5 stitches over 4″. And this new gauge is for unwashed fabric. I expect my gauge to be slightly looser after the finished skirt is washed and blocked, so the final gauge will probably be something like 19 stitches per inch.

So what do you do when your knitting gauge is different from your swatch gauge? Well, this is why you should check your actual gauge while you’re knitting. Ideally, you should do this several inches away from the row currently on the needles, for the same reasons that you should measure away from the edges. If you can’t do this, slip your stitches to some waste yarn and then measure. If gauge is really critical for this project, you can wash and block your work while the stitches are being held by the waste yarn (make sure the waste yarn is white or very light-colored, so there’s no chance of the dye transferring to your project) and then measure again.

In some cases (a hat band that’s too small to go around the recipient’s head), you’ll have to frog your work and start over. But you’ll have more experience with the yarn and can cast on with more confidence this time, knowing that you have a better chance of getting the right size! In other cases— especially if the gauge differences aren’t too great— you can adjust the pattern as needed. If you’re knitting a fitted pullover, for example, you could add extra increases or decreases to your waist shaping (and/or start the shaping a little sooner or later).

Lanesplitter-in-progressWhat did I decide to do about my Lanesplitter? Well, I cast on 130 stitches, so this means I expected the width to be 26″, but instead it’s 26.7″ and will likely grow to 27.4″ after blocking, so 1.4″ difference. I’m knitting this on the diagonal, so this indicates that my skirt is going to be approximately 1″ longer than I’d planned. But the width is determined by the number of rows that I knit, so I will still be able to achieve the fit that I want. For these reasons, I’m going to keep knitting. Once I have a few more inches knit, I’ll be able to hold it up to me and see where it’s going to fall, and then I’ll make a decision.

So tell me… are there any swatching secrets that I’ve missed? Have you found other reasons why your gauge might change between swatch and actual project?

To swatch or not to swatch?

Swatching is one of those things that knitters either love or hate. I think it depends on the kind of projects you knit, and how often you’ve been burned by bad gauge. If you knit scarves or things where gauge is largely irrelevant, then probably swatching isn’t a big part of your knitting life. But if you knit sweaters or things where fit is important, then it only takes one ill-fitting sweater (and all the days or months that went into knitting it) to make you see the value of swatching.

For my Lanesplitter skirt, gauge is important. I don’t want my skirt to fall down while I’m wearing it, and I’d prefer it to end just above my knee. I’d also like it to be long enough to be legal and to fit without looking like I’m wearing a striped sausage casing. Tall order, eh?

Lanesplitter SwatchHaving worked with Noro’s thick-and-thin yarns before, I know that I tend to prefer them knit up at a slightly tighter than normal gauge. I also don’t want this skirt to stretch all out of shape while I’m wearing it, so that’s another reason to work to a tighter gauge. The pattern calls for size 10 needles; I would ordinarily start with size 8 needles for this yarn. I started my swatch with size 7 needles. As expected, the fabric was drapey and had lots of stretch. Too much stretch, actually, which indicated I should go down a needle size. So I changed to a size 6 needle.

This time, I decided to experiment with reversing the angle of the stripe, by beginning the row with an increase and ending with a decrease. Another aspect of swatching that I didn’t really appreciate when I first started knitting was the opportunity to play with the pattern, to try out new-t0-me stitch patterns or techniques. Which increases would look best? Which type of buttonhole? How wide should the button band be? I can play with all of these in a small swatch, instead of getting 6″ knit of a sweater and then deciding that I don’t care for the hem treatment. (Okay, that still happens, but swatching helps minimize some of the ripping and frogging and cursing that often accompany my knitting!)

I liked the fabric from the size 6 needles, but I wasn’t as happy with the look of the increase/decrease edges. So I went back to the original pattern and down to size 5 needles. This fabric felt a bit stiffer than the size 6 swatch. If I had stopped here, I probably would have decided to go with the size 6 needles. But I’ve knit with Noro before, and I’ve found that yarns with silk in them tend to grow and relax once they’ve been washed and blocked. So into a Eucalan bath the swatch went. (I don’t cut my yarn before washing my swatches. I bind off the top section, pull the last loop out a few inches and pass the ball of yarn through, so the swatch won’t unravel. Then I pop the swatch in the water and set the ball of yarn beside it on the sink. This way, I can simply undo the bind off edge and pull my swatch apart when I’m done with it, and I don’t have a small bit of yarn– with extra ends to weave in– if I need the yarn to finish my project.)

As I expected, my resulting swatch was much softer and had more drape after a bath than it did when it first came off my needles. I’ve decided to go with the size 5 needles.

So tell me…

Next up: Winding my Noro and planning the stripe colors. And talking about why swatches sometimes lie! 🙂



My husband calls my gauge swatches “prototypes.” At first I was amused by this, but really, he’s right. A prototype is a proof-of-concept, something that validates what you’re attempting. And isn’t that what a swatch is?

So what *is* this mysterious blob?  I am currently working on Every Last Yard, which is a lovely, seamless top-down sweater by Amy Swenson.  I’m using Madelinetosh Pashmina yarn (in Celadon), which is simply heavenly stuff.  (I’ve made two scarves out of it and am already thinking about what I can knit next with it!)  I’m making pretty quick progress on it, so more pictures to come soon!