It’s a Wrap ; some thoughts on the relationship between gauge and WPI.

I’ve been spinning a lot recently and I’m designing a sock pattern right, so gauge and WPI have been in my mind a great deal.

WPI, or wraps per inch, is the measuring standard used by spinners to determine the thickness of a yarn. The higher the WPI, the finer the yarn.

Gauge (tension in the UK) is a measure of the number of stitches in 4 inches of stockinette. To my mind, an ideal gauge swatch is 6 x 6 inches, with a garter stitch border. I generally block swatches before measuring them.

Gauge is the trickier measure, and thus decreed by fate to be the one most commonly used in knitting patterns. Gauge varies from yarn to yarn, even within the same weight category — the gauge of a worsted weight yarn may range from 16 to 20. And this before we’ve even started knitting.

Individual knitting styles add further variation – a tight knitter will get more stitches per inch on the same yarn and needles then a looser knitter will, making the manufacturers declared gauge nothing but a very rough guideline. Anna Zilboorg observes, in ‘Knitting for Anarchists’ that

“…three or four needle sizes will give me the same number of stitches per inch.”

This agrees well with my personal experience — trying to get gauge by adjusting needle size is a bitch.

It is in Ms. Zilboorg’s elegant explanation of this difficulty that gauge meets WPI. She writes:

“…changing needle size is far more apt to change the number of rows per inch then the number of stitches per inch. This makes sense. Basically, in each stitch two strands of yarn are lying side by side. The yarn continues to be the same width no matter how thick or thin the needle is. However the yarn must go up over the needle and down the other side. If it must go up twice as far and down twice as far, it stands to reason that the resulting stitch will be longer, giving you fewer rows per inch.”

“The yarn continues to be the same width…” There in lies WPI, and why you can measure wraps per inch accurately around a ruler, a spare knitting needle, or any of the lovely and variable WPI tools available to the spinner.

Practically speaking, I think that this means you’d be better off matching the WPI of the yarns when you want to substitute one for another, and that it’s probably easier to get gauge through appropriate yarn selection then through needle changes.

references

‘Knitting for Anarchists’, Anna Zilboorg

Measuring WPI, Spindlicity, Spring 2006

Standard Yarn Weight System, Yarnstandards.com

Personal master gauge swatch.

Simple knitting after the hat. I spent today making a personal master gauge swatch. This is knit in Galway Wool by Plymouth – a 100% wool worsted weight. I cast on 40 stitches, starting with size 11US needles, then knit 4 inches of stockinette, working my way down in needle size. From right to left you can see size 11, size 10.5, size 9, and size 8. I don’t have any size ten needles! I’ll need to get some. I had been hoping to go all the way down to size 4 – but I ran out of yarn. I was using a partial ball left over from some hat making. I’m going to get myself a full skein when I get the size 10’s, and make a full swatch.

The needle sizes are separated by rows of garter stitch – it shows me where I switched, and also takes the rows I switch over out of stockinette, so they don’t confuse my measurements. It’s wet right now, but once it is dry, I will be able to measure my gauge on the different needle sizes, and compare that to the recommended needle/gauge for the yarn. Then I will know roughly what my personal gauge is for this yarn – if I knit tight or loose, if I am getting row and stitch gauge proportionally or need to keep aware of row gauge issues.

I’ll still need to do project specific gauge swatches — but now I will have a better context for what the swatches are telling me, and where to start when I start swatching.

How to knit a gauge swatch.

Cast on 30 stitches in the yarn you are swatching, on the needles you are using. Knit three rows of garter stitch, then hold 3 stitches on each side of the piece in garter stitch, and knit the center in stockinette. The pattern for this is RS – K3, k24, K3, WS – K3, p24, k3.

Knit in pattern until the piece is 4 to five inches long, then knit another three rows of garter stitch and bind off.

Block the swatch very gently – nudge it carefully into as true a rectangle as you can without stretching it. This helps ensure that the gauge it reflects will be accurate.

It will look a lot like this:

This swatch is knit in worsted weight yarn (Galway Highland Heather) on size five needles. It’s stitch gauge is 5.5 – 6 stitches an inch, and it’s row gauge is 8 rows an inch.

This makes a nice sized swatch – the one in the picture is 5 and a half inches by 4 and half inches. The garter stitch edging helps keep the stockinette from distorting, making it’s gauge more accurate, as well as easier to read.

To read the gauge, I use a tape measure, and carefully line it up along the row or column, then count the number of stitches per inch — I read the gauge in at least three places, to ensure that I am knitting evenly — on this swatch, my row gauge is good, but my stitch gauge varied slightly, so I know need to account for that when I knit.   Since I am making up my own pattern (pretty much) I can account for it by adjusting how many stitches I cast on, rather then trying to change needle sizes to get gauge.

And now I am ready to start my knitting.   The project that has prompted me to this unusual level of precision finickiness?

A plain ribbed hat.