Here's the stuff I have slowly learned over time about yarn fibres. This is by
no means extensive, but it's the basics that you may need to know so that you (unlike me) don't have a few early projects get ruined because they were made out of the wrong thing.
A quick note: if you're wondering what it's made of, check the yarn band! It should say on it what fibre it is.
There are basically three categories of fibre. Yarn snobs will get puffed up about breaking them up this way, but when it comes to their qualities, this is the easiest way to divide them. Fibre is either animal-made, plant-based, or plastic.
Here's a really simple rundown:
Animal-made fibres include alpaca, angora, bison, camel, cashmere, llama, merino, mohair, qiviut, yak, and the most common, wool. All of these are some type of animal hair. The only animal-made fibre that doesn't act like the others is silk, which while made from silkworms, isn't a hair and thus acts a bit more like a man-made fibre. Animal-hair yarns tend to be very warm, due to the fibres being made to trap heat near the animal's body.
However, animal-made yarns can cause allergies and be rough if not processed correctly. Wool especially has
lanolin, a natural oil produced by the sheep that can be irritating to the skin. Due to these allergies, most hospitals and some charities won't accept items made of these yarns, because those with immune deficiencies can't handle that.
Another downside to many types of wool and other animal yarns is that they can felt. Check your yarn label for how it needs to be washed. Most of the time, a hand-wash yarn has a tendency to felt. This is when small scales on the hair open up in heat or water and can get stuck together with friction. It shrinks the item and sticks it together into... well, felt. While sometimes this is a wanted outcome, such as with slippers or some bags, most of the time you don't want your item suddenly shrunken and felted.
Plant-based yarns are made from plant fibres. This includes bamboo, cotton, hemp, linen, and soy. These tend to not be nearly as elastic as animal-made yarns and can shrink slightly when washed, just like any cotton clothing. They're less warm, which makes them great for spring and summer items. The drape can also be better, due to no sticking scales on the fibres, and linen especially is valued for its flow. Hemp is known to be durable. Bamboo is slightly rarer to see used, but it's got a lovely sheen.
My favourite part of plant-based yarns is that they're able to be thrown in the laundry so easily, but there is a downside because plant-based yarns also can give allergies. They also tend to pill with use and friction.
Finally, there are
man-made fibres, or, as I call them, plastic. This includes acrylic, metallic yarns, microfibre, nylon, polyester, vinyl, rayon, and tencel. By far the most common of these yarns are acrylic.
Acrylic gets a bad rap. When it first was made it was scratchy and hard and keeps that stigma today, but now there are hundreds of acrylic yarns that are soft. Here are the pros and cons.
Pros: Acrylic is machine washable, durable, and hypoallergenic (hospitals tend to ask for things to be made of acrylic for this reason). Acrylic is also cheap, which makes it a great choice for large projects like blankets and afghans. It doesn't shrink or felt, though the softer ones can pill (Check the washing labels).
Cons: Some acrylics
can be scratchy and hard (though there are ways around this. I'll maybe make a post about softening acrylic later). Also, acrylic yarns give off small pieces of plastic - they shed, like most other yarns - and these microplastics can become dust and infiltrate our ecosystem (this is one of the things that causes microplastic pollution). Non-synthetic yarns based on plants or animals biodegrade better, but things used to process them such as bleaches or dyes can still harm the environment.
Here are a few tips:
- Try to stick to one category of yarn for a project. In other words, don't use cotton and acrylic to make stripes - the cotton will shrink and the acrylic won't, giving you a wonky texture. Wool and acrylic used in the same project mean you have to wash your entire item by hand so it doesn't felt.
- There are mixtures of fibres in many yarns! Superwash wools are wool yarns mixed with other fibres so they're less likely to felt, and most sock yarns have man-made fibres for strength so the socks last longer. Wool mixed with cotton will be a little less warm and less itchy, while cotton mixed with a man-made yarn is often more durable.
- Wool is good for really warm items, while acrylic is great for large items, or anything intended to be gifted (easy-wash is excellent for those who don't know how to hand-wash knits). Cotton yarns are excellent for summer, underclothes, and items that you want to be more breathable. Use man-made fibres for things you want to last for ages.
- Finally, do some research if you're unsure. The Ravelry forums are a great place to start, but also the yarn manufacturer or the people at your local yarn shop often have some really great ideas!