As a new knitter, you may be surprised at how often knitting books and yarn stores will recommend wool yarn for projects. If your experience with wool garments has been mostly from garments available from major retailers, you may be surprised that even 100% wool can be very soft and gentle to the skin. You may even have wondered if you are allergic to wool, when you may not be allergic to it at all.
True wool allergies are very rare. Occasionally, someone will be allergic to the alcohols that are naturally present along with sheep's fiber. These people will break out in a rash on their face or hands when they are exposed to lanolin or other wool alcohols. An allergist can test for this response by performing a simple skin prick test with a small amount of the possible allergen, and then waiting to see if such a reaction develops. For a person who is truly allergic to wool, they should look at using and wearing other fibers.
What is more common is a sensitivity to wool. Wool is a natural fiber from sheep, with each hair having scales and crimp. Sheep's wool has as many variations as does human hair. Some humans have fine soft, straight hair, other humans thicker courser hair with a great deal of curl or crimp. Different varieties of sheep have been bred over several hundred years to have different properties - some sheep have very fine hairs with little crimp and smooth surface to each hair, while other breeds are known to have lots of crimp and rougher strands that cause the wool to spin up easily. All kinds of variations and combinations exist in sheep's wool. In addition, the quality of an individual sheep's wool can vary tremendously. There are several different grades of sheep's wool, with the highest, most expensive grades often being the ones that produce the softest and most insulating yarns.
Sheep's wool that is scalier will produce a rougher feeling, almost prickly yarn. This same scaly feature allows the yarn to spin together and stick to itself well, so that these wools often produce thick and warm yarns that are great for outerwear. These same yarns would be prickly close to your skin, and many people may be sensitive to them, The scaly nature also allows these yarns to pick up and hold other types of allergenic dander, which can lead to the person wearing the garment believing they are allergic to wool when in reality they are reacting to something else the yarn has picked up - such as cat dander, dust mites, or a pollen.
Since sheep are raised in the outdoors, it is necessary that the sheep wool be cleaned before it is spun into yarn. Many different chemicals are used in the cleaning process. Sometimes, people who react to wool are reacting to the chemicals that were used to clean the wool. Buying a good wool wash from a knitting or spinning supplier can help the knitter or garment owner to wash out any allergens or chemicals that a garment may have picked up. A gentle pH balanced shampoo, such as many baby shampoos, can also be used to wash woolens.
Wool that has been bred and processed for the best skin feeling yarns will cost more than lower grade wools. When shopping for wool sweaters a major retailer who advertises a soft merino wool sweater that feels prickly may simply be using a lower grade merino or merino that was heavily treated with harsh chemicals. Feeling the garment will tell you a lot about the quality and nature of the wool used to make the garment. At a yarn store, touching the skeins or knitted samples will let you know if the qualities of the yarn are suitable for your project.
If you believe you are sensitive to wool, it is worth seeing how the many different wool yarns available feel. Wool has many unique properties that lead it to be one of the best insulating fibers available. It retains its warm insulating qualities even when wet. The many different breeds and yarn spins that are available allow a knitter to get just the right features they want for a particular garment. If you are knitting for someone else who has always thought they were sensitive to wool, you may want to educate them about wools positive qualities - and its varied qualities so that they can see if they enjoy wearing a different and softer wool yarn than what they have tried in the past. You can also explore the many wool blends that are available, in which the wool has been mixed with another fiber to produce a yarn that combines the characteristics of both fibers.