Substituting Knitting Yarn

So, you've found a great knitting pattern for a beautiful autumn pullover and you've just picked up a bargain bag of yarn that knits up to roughly the same tension. I've substituted yarn for quite a number of knitting projects, so last year I decided to knit Lori Versaci's 'Vines' (published in Knitty, Deep Fall 2010) with a bargain bag of Classic Elite Yarns Classic One Fifty  and I was pretty confident it would work. The pattern called for a yarn with an identical tension, Classic Elite Yarns Fresco, and after knitting a large swatch in the slipped stitch pattern, my tension was spot on. It was a mammoth knit, using just over 1800m of yarn and taking me over two months of solid knitting. And the outcome? Well, as you can see, a bit disappointing. While I had substituted a sport weight yarn with another of the same weight, the composition of the yarns is quite different and this has dramatically effected the outcome. My cardigan is not light and snuggly and soft; it is dense, a bit unforgiving, heavy and hot.
Lori Versaci's Vines Cardigan on Knitty and my Vines on Ravelry
Knitwear designers talk about 'hand'. Hand is how the yarn feels when knitted up. It is easy to substitute a yarn that is like for like, say Filatura di Crosa's Zara for Rowan's Pure Wool DK as they are both plied DK or 8ply woollen yarns with roughly the same meterage on the skein. In this case, all you need to do is knit a quick swatch to check your gauge and needle choice are correct for the pattern and start knitting. But if your knitted fabric has a different 'hand' from that the designer intended, there is a fair chance your outcome will be as disappointing as mine. The problem was that my yarn, Classic One Fifty, is a 100% wool firm plied yarn which creates a firm structured fabric made worse by the structure created by the slipped stitch pattern; whereas the recommended yarn, Fresco, is a wool alpaca angora mix yarn, which although plied, retains it's 'lofty, soft hand' enhanced by the slipped stitch pattern. Hmmm…
So, back to the task in hand. This autumn I've decided on a new Louisa Harding pattern, 'Faith' from the Delphine and my stash of Teva Durham's Loop-d-Loop River, a worsted/aran weight (or 10ply) blend of cotton and cashmere.
A close up of Louisa Harding's Delphine yarn, Louisa Harding's 'Faith' from Delphine and a close up of Teva Durham's Loop-d-Loop River yarn
So, let's go head to head on the yarns.
Delphine (specified in the pattern)
Weight: worsted
Meterage: 100m per 50g skein
Tension (gauge): 18 stitches and 24 rows over 10cm
Needle size: 6mm 
Composition 100% cotton
Texture: chain
River  (my choice of yarn)
Weight:  worsted ( aran (Ravelry)
Meterage: 94m per 50g skein
Tension (gauge): 18 stitches and 22 rows over 10cm
Needle size: 5mm (for me 4.5mm as I knit cottons loosely)
Composition: 90% cotton and 10% cashmere
Texture: plied with a very loose soft twist

Weight: Ravelry bases yarn weights on both stitch and row count, so River yarn to be classified on Ravelry as aran rather than worsted weight on based on stitch count alone. Row count is not as important as the stitch count as this is where most knitters differ and is easily adjusted for as you knit up the fabric.
Meterage: meterage per skein tells you how heavy the yarn is. if the yarn you intend to substitute is substantially heavier than the yarn specified your project will be much heavier, droop unattractively perhaps and be overly bulky. If your yarn is much lighter, your finished garment will not hang in the way the pattern example does and will tend to ride up and stretch sideways.
Tension (gauge): see note above about weight. These two yarns are essentially the same, I'll may just have to play with my row counts.
Needle size: it really doesn't matter what needle size you use as long as it creates the type of fabric you want, so start with the needle recommended on the yarn and go up or down from there. If you don't have a great needles collection many yarn shops will let you sit down and try several different needles if you've bought your yarn there and buy the needles once you've got the tension you want. Remember you only have to knit one tension square for every yarn you knit with. Once you have it, you can refer back to it if you want to use that yarn again. If you don't keep your tension square, note it on the ball band, in your journal, or on Ravelry so that you can refer back to it when necessary.
Composition: relates to meterage and weight. In this case the two yarns are similar.
Texture: I'm replacing a cotton chain yarn with a loosely plied cotton/cashmere yarn. Both will be a bit unforgiving as cotton does not have the same natural 'stretch' as wool. 
While I'm attempting to knit a similar pullover, I don't want my pullover to be as loose and drapey as the one in the pattern book, so I'm hoping my plied yarn will give my finished project a bit more structure. 
Getting Started
As I have a real problem knitting with cottons and struggle with tension every time, I usually have to go down at least one need size and I find I end up with a difference tension on my tension square than on the project pieces. So this time followed the advice of Leonie from the WoolBaa and knitted a sleeve instead of a swatch square using 4.5mm needles. This gave me a much better idea of my tension, the drape of the knitted fabric and how it felt on my skin. It also gives me a large section of work to measure my row gauge on a piece with a bit of weight.
My sleeve 'swatch' and measuring gauge
So I'm happy. My knitted stitch tension is 18 and my row tension is 23. And I'm really happy with the 'hand' of the fabric on the sleeves, so I'm going to take a leap of faith and start on the body pieces. In the end, substituting yarn is a creative process, so you always have to step off into the unknown, and that's the joy of it!
Ms Jane is Melbourne-based artist who earns her living taking photographs and spends it all on knitting yarn and sewing material. You can see her knitting and sewing projects here or find her as msjane on Ravelry.