How to select yarn and hook for crochet wearables

Are there any parameters that should be considered when selecting the yarn for crochet wearables? Yes definitely there are.

If you are following any pattern, then it gives details about the yarn to be used. It is not possible to use the exact yarn. But go for an alternative that is similar to the recommended yarn as much as possible. Check for the weight (thickness) and composition.

Yarn thickness:

If you're following a particular pattern, then this is the first thing to look for. Yarn is available in many thicknesses ranging from thread to super bulky. So if pattern calls for worsted weight yarn, you should always use worsted weight yarn. If you use thinner or thicker yarn, it will change the size and the fabric texture or drape of the finished garment. 

In general, worsted and bulky yarns are used for warm and cozy winter garments and lightweight yarns are used for summers. If you want to use worsted weight yarn for summers, you can use a larger hook to create airy fabric or use lacy stitch pattern. Similarly if you want to use lightweight yarn like DK for winters, try smaller hook and textured, heavy stitch patterns like basketweave stitch. 

Yarn composition:

The most widely used yarn is acrylic.

Wool is used for warm winter wears. It is durable and has moisture wicking property. But it feels scratchy against skin and tends to pill. Some people are allergic to wool. Other options for winters are merino wool, alpaca, angora, cashmere etc. But they are quite expensive. Cotton is popular choice for summers. Silk yarn is good for delicate, intricate patterns and garments that need drape.

Hook size:

Which hook should you use depends on many factors. But as a initial guide always refer to yarn label. In general, 2.5 - 3.5 mm hook used for sport weight yarn, 3.5 - 4.5 mm for DK yarn, 5 - 6 mm for worsted weight yarn and 6 - 7 mm for bulky yarn. I crochet loosely, so you might need a larger hook. For stiffer fabric, use smaller hook. For flowy fabric with some drape, use larger hook. Also remember that the stitch pattern used will also affect the stiffness/drape of crochet fabric. Some stitches like waistcoat stitch, spider stitch create stiff garments, where double crochet (dc), herringbone half double crochet (hhdc) create flowy fabric.

For stitches like waistcoat stitch, even 8 mm hook and worsted weight yarn creates slightly stiff fabric.

I used worsted weight yarn and 8 mm hook for this waistcoat stitch beanie in all sizes.

In the end all these factors combined (yarn composition, thickness, hook size and stitch pattern), will determine the characteristics of crochet fabric.