I know you are itching to dive in and start your project, but before you even purchase yarn, there are a few things you should know.
The pattern you have chosen will call for a specific weight of yarn and a specific needle size. This combination is meant to give you what is known as “gauge,” or the same number of stitches and rows per square inch as the pattern designer. However, since knitter’s personal gauges can vary widely (and, as a beginner, yours is likely to be loose), it is always best to make a gauge swatch before beginning a pattern. (See “Making a Gauge Swatch”.)
That being said, the Building Blocks Cowl/Hood does not require you to make a gauge swatch before you begin. I know you just want to start making something!
Yarn Weight and Needle Size
Yarn weights from lightest to heaviest (or, if you prefer, skinniest to thickest) are:
DK (Double Knitting)
Each yarn weight has a typical range of needle sizes that produce fabrics from dense to airy. The “middle-of-the-road” size is usually listed on yarn labels with the typical gauge you will get using that needle size. For more information about which needle size goes best with what and expected gauges, see the Craft Yarn Council’s page about it.
Note: For tips about the different styles of knitting needles and what they are for, see Choosing Needles.
The Building Blocks Cowl/Hood pattern uses Bulky Weight yarn (denoted on yarn labels using the symbol on the right), and the middle-of-the-road needle size for this yarn weight of 6.0 mm (in the Canadian system).
In the United States and UK, needle sizes have their own measuring systems. 6.0 mm in Canada is size US 10, UK 4. Needle size conversion charts are only an Internet search away. (Try this one.)
For your first several projects, choose yarn that is well-structured, not fuzzy, bubbly, hairy, or “fancy” in any way. The colour should not be too dark, as this makes it difficult to see what your yarn is doing, and you need to be able to see that in order to fix inevitable mistakes. Smooth, structured yarns give better “stitch definition,” meaning the texture created by alternating your knit and purl stitches (as in the Building Blocks pattern) or knitting stitches in different orders (as in cables, etc.) can take centre stage. “Fancy yarns” are best on projects that use mostly Stockinette Stitch (knit one direction and purl the other), and sometimes Garter Stitch (knit both ways), or they can make wonderful trims or “interest” yarns when worked alternately with other types of yarn textures. Some, such as eyelash yarns (ones that appear “hairy”) work up best while being held double with another “plain” yarn.
Within each yarn weight there can still be a great deal of variance for gauge. If you are substituting yarns, make sure the yardage of the yarn per weight matches the recommended yarns as closely as possible. Also pay attention to fibre content. Different fibres have very different properties and not every fibre is suited for every project.
Many beginner knitters (myself included) have begun with acrylic yarn because of availability and price. Oh, how I wish I had made the switch to natural fibres as soon as I started knitting! Acrylic can have its place, but its lack of structure means that your finished garments will lack the crispness you can achieve with natural fibres. Not only that, on the scale of warmth, it ranks near the bottom.
The best natural fibres for winter projects are wool or alpaca, as both are very warm (even when wet) and will wick moisture away from your skin. Superwash wool will resist shrinking when washed. Roving or other types of wool will need to be hand-washed in cold water and laid flat to dry to avoid shrinking. Nylon or acetate is sometimes blended with these fibres for strength, while acrylic is sometimes blended in for lustre or to reduce the cost.
Summer projects are best made with cotton, linen, or rayon from bamboo or other plant-based fibres.
Luxury fibres like cashmere, angora, or other animal fur fibres are perfect for indulgent projects like neck warmers. Many of these have a “halo,” so are best used with plain stitch patterns (Garter or Stockinette).
Wool comes from sheep, alpaca comes from, well, alpacas. Alpaca yarn has greater “loft,” meaning it captures more air and can therefore be as warm as wool while being lighter weight. Cashmere comes from goats, angora comes from rabbits.
Because of this difference in weight for different fibres, make sure you have the minimum required yardage for your intended project if you will substitute yarn from that suggested by the pattern designer.
This is far from an exhaustive tutorial about choosing yarn. For more details, see this blog post about how to substitute yarn.