You know you are getting deep in the weeds of yarn, so to speak, when you start asking about ply… At its most basic, ply refers to the number of strands of yarn twisted together. Why does this even matter? We are glad you asked! You can break most yarns down into 3 categories: Unplied, Single Ply and Plied. Let’s take a look at unplied first…
Unplied yarn has no (or very little) twist to it. It is prone to breaking if you pull too hard but can still make a very durable finished piece. Many of Brooklyn Tweeds yarns like Loft, Shelter, and Quarry are unplied and quite lovely to work with. Our one caveat! If you are a tight knitter or crocheter, beware- because it is more easily broken, it can be hard to deal with.
Single Ply, like unplied yarn, means you just get the one strand - but it has a twist to it. A good example that we carry at the store is Malabrigo Mechita. It is typically soft and can be lovely to work with and wear but it has some drawbacks. It is less durable than plied yarn which means you need to be careful with how much stress you put on it while working with it. Also, it is more likely to do the dreaded pilling since there is little to no twist to keep things together.
Plied yarn refers to all yarn with at least 2 strands twisted together. Plied yarn does wonderful things for stitch definition in projects, and also affects the durability of the finished piece. Especially if you are making something that gets lots of wear like socks, sweaters, and blankets, you are definitely going to want to use plied yarn. Blue Moon Socks That Rock Lightweight is a great example of a sock yarn that uses a tight ply to make it wear well (rather than adding nylon).
BOTTOM LINE - HOW WILL IT WEAR?
Typically it comes down to the project itself and how much wear you expect it to take. “Will it pill?” may be one of the most common questions we get (after “Do I really have to knit a gauge swatch?”) and ply plays a lot into how the project wil wear. Generally, plied yarn will pill less quickly but, honestly, everything will pill over time. What yarn and what ply depends on how much that impacts the functionality of the garment, as well as your personal preferences.