But there comes a time in many crocheters' lives when they realize there is an entire world of yarns outside the Big Box Store. They'll begin to experiment with wool and cotton, then maybe move on to the more exotic silk and alpaca. And then suddenly the yarn world can start to seem overwhelming in options. How can one possibly narrow down all the available options to the particular project in mind?
While a lot of it is going to come down to individual preference, we've got some tips to help you narrow down your choices. As we can't possibly cover every single type of fiber in existence, we'll focus on the fibers currently carried in Crochet Kitten's Bazaar.
This manmade fiber is the most common fiber for Big Box Store yarns, but it can also be found in many higher end yarns. I went through a brief period in which I only wanted to use yarns with natural fibers, but I had to admit that acrylic also has its place, especially for those with fiber allergies. Choose acrylic when cost is a factor or when making items for charity (such as chemo hats or items for the neonatal intensive care unit). Acrylic has also been my go-to lately when making items for children (especially amigurumi), because it is so soft and cuddly. You may find that some acrylics tend to "pill" after washing, but this can be avoided by killing the yarn after it's crocheted (you'll be amazed how much the texture of Red Heart Super Saver improves after killing it). I've found that higher end yarns have less tendency to pill, but that doesn't mean you should go out and buy the most expensive acrylic you can find. Our favorite right now Cascade Cherub Aran because it's inexpensive and doesn't need to be killed to avoid pilling, and it's warm, to boot.
Alpaca is a popular alternative to wool for those with wool allergies, but word to the wise--we have a friend who is allergic to alpaca, so don't assume that it's a completely hypoallergenic fiber option. If you are unsure of someone's allergies, acrylic is the way to go. That said, alpaca is my favorite winter fiber because it is six times as warm as wool. The only reason we don't use it more often is because it's also more expensive than other fibers. So if warmth is your main concern and money is no object, go for alpaca! Otherwise you may wish to opt for less expensive (but still warm) fibers such as wool or acrylic.
A while ago we had an entire blog post dedicated to cotton, but in sum, we like cotton for items that we don't want to trap heat, such as summer wearables. Cotton also lacks elasticity, which means once it's stretched out, it's going to hold its stretched out shape. This means it's not a good choice for anything that you would expect to be stretchy, like a beanie hat or gloves (you would want warmer fibers for those anyway), but is great for items that you would want to be more sturdy, such as shopping bags. It is also excellent at absorbing water, which makes it a popular choice for dish cloths. And cotton thread has such excellent stitch definition that it's pretty much the only fiber used to make intricate doilies. It's not the softest fiber, however, so I would avoid it in anything that you want to be soft and cuddly.
Mohair is used for two main reasons: its warmth and its aura. By "aura," I mean that the yarn has bits of fiber that stand out and create a fuzzy (yet cozy) look to the finished project. It is incredibly difficult to crochet on its own though, so I would recommend either crocheting it together with another yarn or buying a mohair blend (although sometimes mohair blends loose that fuzziness that's associated with the mohair). It's also difficult to rip out if you make a mistake, so it's not the best choice for beginning crocheters. Use mohair only when washability is not an issue and when you're not concerned about stitch definition (which refers to the "crispness" of the stitch).
You know you've really taken your crochet to the next level when you start considering crocheting with silk. I love the look of silk. It gives excellent stitch definition and makes any project feel luxurious. However, silk has the same issue as cotton in that it has no elasticity. Since you wouldn't want to make something as utilitarian as a shopping bag in silk, care must be taken when making wearables to select a garment in which elasticity wouldn't be an issue, such as a shawl. And silk can be cost-prohibitive as well. For these reasons, silk is often blended with other fibers to make it both more elastic and more affordable.
We also did an entire blog post on wool a while back. Wool is famous for its insulating properties (and I'm talking about 100% wool, not wool mixed with other fibers or imitation wool). It's a common fiber, so its fairly inexpensive (though not as inexpensive as acrylic), and is the most popular choice for winter wearables. And did you know that wool is water resistant? Back before there were disposable diapers, babies would often wear wool "soakers," which were short pants worn over the cloth diaper that would wick water away from the baby's skin and keep the outer clothes dry. That's pretty high tech for the 1800s (heck, even up through the 1950s), and we think it's still a good thing to keep in mind today. Picture it: a wool winter hat that wicks the melted snow away from your head. I like this idea. The big issue with wool, of course, is washability. Most wool will felt and shrink when washed, and then your project is ruined. You can get what's called "superwash" wool, which has been specially treated to make it machine-washable, but I would still recommend taking care when washing it. (This is another reason why acrylic has become my go-to fiber for children's projects.) And of course, some people just don't like the feel of wool against their skin.
If you have any questions about any other fibers, please feel free to ask in the comments!