yarn substitution

You’d think that if a pattern calls for 4ply yarn, you’d be able to take any 4ply yarn and knit a successful project. So why does it so often go wrong?

Conventional substitution theory goes:

Take the number of metres needed to complete your project (hopefully the pattern gives you that, otherwise take the number of skeins needed and times by the number of metres in a skein). Divide this total amount by the number of metres in the skein you want to use.

total needed / by number of metres in skein = number of skeins

For example: you want to make a shawl that takes 935m of yarn / 5 skeins of 187m each.

The yarn you want to use is 200m / skein.

935m / 200m = 4.675 skeins

Answer: you'll need 5 skeins of your substitute yarn to make the project.

So why isn’t this method foolproof?

Firstly, yarns are loosely classified according to the number of metres per 100g. Laughing Hens has a really good guide:

Take a note of that 4ply range: a whopping 251m to 499m / 100g. That’s an almost 100% increase in yarn length from the shortest to the longest! So you'd think that if you chose a substitute that was close in range at least, logically they'd be a similar thickness and all is ok.

Let's take a look at three examples in the range 350 - 375m / 100g, quite a small range given the rule. Note the thickness:

On the left is Rowan’s Felted Tweed DK (50% wool, 25% alpaca, 25% viscose) at 350m / 100g. They’ve classed it as a DK weight. In the middle, a merino linen blend at 366m / 100g. You can see it’s the thinnest of them all. On the right is my own 4ply cashmere yarn at 375m / 100g. 

Given how varied yarns can be even in such a close range, it’s no wonder our projects don’t always work out as expected.

So what to do? Warning: you may not like it if you're a jump-in-and-see knitter.

Swatching

Take your substitute yarn and with the recommended needle size, cast on the number of stitches + 6 for the gauge of your pattern. Knit an inch, and that will already give you an idea if you’re close to the recommended gauge. If you’re not, undo it and change needle size up or down. Are you now getting gauge? If yes, and this is the most important consideration: do you like the fabric you’re knitting? Will it suit the finished object? For example does the pattern call for tight colour work and does your fabric fit that bill? If so, carry on for a couple more inches and check the gauge again. Still happy? Then I think you’ve got a winner.

It’s a quicker method than knitting 5 or so inches, blocking and then checking only to find it's wrong, and even better than knitting the whole project and being unhappy with the result.

What about substituting yarns-held-together projects?

Well you multiply the complexity of the above considerations by the number of yarns you're going to hold together = headache.

Here's what I'd do:

1. Choose the thickest of the recommended yarns and use those length requirements to be the number of metres you'll need of each composite yarn.

2. You really do have to swatch here, so choose your combinations and try a mini swatch as above. Adjust the yarns as you like to achieve the effect you want. If you're getting gauge and you like the fabric, you're good to go.

How can I help?

Buying enough cashmere yarn for a project without knowing that it'll work is a risky business. So I offer a 10g 'try me' skein in DK or 4ply to test whether it'll be right for your project, pot luck as to what colour it'll be. It helps me as I can use up colour test skeins. It helps you as you can buy a small amount at a discount and see whether it's right for you.

Do you have your own foolproof method? Please share!