Wool is one of the most common fibers for handknitting. It comes in various grades from very rough, mostly used for outerwear, to very high micron count merino, which is very soft and used for everything from next to the skin clothing and baby products. Depending on the grade chosen it can be very durable. Wool can hold a large percentage of its weight in moisture before you begin to feel damp or cold. It is often blended with other fibers to create more durable or special blends.
Wool is among the less expensive choices for knitwear.
Alpaca and Llama
This fibers are from large mammals from South America. Their coats are known for the softness and warmth. Their wool is also usually considered somewhat hypoallergenic. It can hold a larger percentage of moisture then wool before you will feel damp or cold. Llama and Alpaca have less crimp in their fiber which means they have less bounce and more drape. Pure Alpaca and Llama are very soft and has a lot drape. This makes it very good for scarves and shawls. They are also often blended with a sheep wool to give it more bounce and stretch. As a warning these fibers are not the best for anything which needs to retain its shape.
Silk comes from the cocoons of silk worms. There are two major kinds of silk. The first kind of silk is spun from the unbroken thread domesticated silk worms. These worms cannot live without human intervention and spin a very soft and very delicate silk. The second form of silk is spun from the broken threads of silk after wild silkworms break open the cocoon. This silk is also very soft but not as strong and takes dye in a very different method leading to a very different looking fiber. Silk is very strong and has a lot of shine. However it does not have much stretch or bounce. This means once it stretches into a shape it will not bounce back. It is often blended with wool to give it more stretch and softness. Silk will also alternately keep you warm or cool depending on what the outside weather is like. Silk is very often more expensive then other fibers.
Cashmere is the very soft undercoat of a few specific breeds of goats. Cashmere is very, very soft. However it is very delicate. This means it is best used for objects which will receive very little friction or hard use. Cowls, fingerless mitts and scarves are the best use for it. It is also very often blended in small amounts to give extra softness and loft to wool blends. Cashmere, like silk, is very often expensive because of the way the goats are raised and the amount which can be harvested per year.
Cotton is a fiber which is spun in many ways to create many different kinds of yarn. Cotton is often used to make warm weather and baby clothing. Cotton blends are also very common since cotton does not have much stretch and blending it with synthetics or wools creates a more comfortable fabric.
Other Luxury Blends
Quivit, Muskox, Camel, Possum and Bison are all newer animal fibers on the market. These are are very soft and very delicate. They are also very, very expensive.
Milk, corn and bamboo are all man processed fibers which mimic the properties of silk with less expense for the buyer.