Some of the most common questions we are asked by our customers are, “Can I make X out of Y yarn?,” “Can I use A color to make B?,” and the umbrella question that covers it all, “I’d like to make a sweater, what yarn can I use?” To which our answers are, of course, absolutely, and any yarn that you please!

Knitting, to me, is all about personal choice, and it has always been my general philosophy that the yarn and the patterns were simply there to give me the tools to make the things *I* want to make, the way that I want to make them. I knit for the pleasure of it. I knit because it’s relaxing to me. I knit because I love to watch the way the needles turn string into fabric, and because I love the way a yarn feels running through my hands as I knit it up. So I don’t knit anything I don’t want to (unless it is for a gift from someone very, very special – then, there are sometimes exceptions). I don’t really like knitting socks, so I don’t really knit socks. I love knitting sweaters, so I cast on for a new one practically every week. Laceweight yarn tends to make me crazy, so I don’t knit with a lot of laceweight, even if I want to make a lace shawl. A nice squooshy worsted weight pleases me deeply (plus, it knits up so quickly!), so I knit with a lot of worsted weight yarns.

So, how do you get it your way, even when the pattern is written another way? Issue the first: yarn substitution.

There are two kinds of yarn substitution. The one that I’ll talk about today is subbing in like for like. This type of substitution, I think, is much simpler – this is when you want a yarn that is the same weight as the yarn used in the pattern but don’t actually want to use the yarn in the pattern. If you are subbing in like for like, there are basically two key issues to consider:

Fiber content – Certain types of fiber have a dramatic effect on the way a yarn knits up, hangs, and wears (silk, cotton, I’m looking at you here). Silk, for example, offers a lot of drape and almost no stretch, while wool tends to be very springy with less drape. A sweater knit from a 100% wool yarn will be less drape-y than the same sweater knit from a 100% silk yarn, which may stretch and lose its shape. Even in a smaller category like wool, a superwash merino wool is typically a lot more densely spun and has less halo than something like a blue-faced leicester wool, giving the same garment knit with each yarn a different appearance. Unless you are prepared to modify your garment to combat differences in fiber types, it is usually best to stick with a yarn that has comparable fiber content to the yarn called for in the pattern.

Plied versus single-ply – If the yarn used in the pattern is plied, substituting a single-ply yarn will give you a garment with a more relaxed drape (after blocking) and less stitch definition. Conversely, substituting a plied yarn for a single-ply will yield a crisper stitch definition. This can be detrimental to patterns that utilize halo, such as the ever-popular Whisper Cardigan (Ravelry link). For the Whisper Cardigan, which was knit with a single-ply (Malabrigo Lace), if you substitute in a plied laceweight like Madelinetosh Tosh Lace, your stitches will show more crisply, making the sweater look almost gossamer from afar and possibly too hole-y up close. To avoid this, typically you’ll want to move up one yarn weight when subbing a plied yarn for a single-ply yarn (Tosh Sock, in this case, would be a better choice).

Substituting in plied yarns for patterns that call for single-ply yarns can also add durability if you are concerned about wear and tear on your particular project. SweetGeorgia’s Merino Silk Aran is a great plied substitute for Lorna’s Laces Lion & Lamb, for example, because it offers a similar yarn weight with similar fiber contents so the yarn’s look and feel will be similar. However, the finished garment will certainly have less drape in the SweetGeorgia, due to the plies, so it is something to keep in mind.

Keep in mind also that these are merely guidelines, and only apply if you like the way the designer’s finished project looks. If you like his/her version but think you’d prefer something a little different, small changes like fiber content or number of plies are an easy way to do just that without a lot of extra math. Or, if you’re like me, you always to knit a pattern in a yarn weight and fiber type that is totally different from the original pattern, and then you have to move to the second type of yarn substitution, when you just sub in the yarn you want to use and do the math to make it work. And that … is going to have to be a whole ‘nother blog post! With pictures, too, next time.