Nobody likes to make gauge swatches. It's a thankless chore, preventing you from getting to the fun stuff. But I'm getting ahead of myself. What is gauge?
knitting gauge (or tension): the number of stitches per inch (or cm) and number of rows per inch (or cm) in stockinette (unless the pattern indicates otherwise) stitch.
Easy, right? Almost every patten, whether it's a tiny baby bonnet or an extra-large cardigan, warns you to CHECK YOUR GAUGE. Even with the menacing ALL CAPITAL LETTERS, I still sometimes neglect to do it because I regard it as a PAIN IN THE ASS. If you're wondering how one checks their gauge, there's a nice (albeit sparse) how to here. The bottom line: if you have more stitches/rows per inch than indicated in the pattern, your extra-large cardigan could end up baby sized, and on the flip side you have less stitches/rows per inch, your baby bonnet could end up being your new hat. So you knit this worthless (I know, people do cutesy things with them sometimes, but the only cutesy thing I've ever done is throw them into a drawer with the promise that I'll look up some cutesy thing to use them for then never look at them again) little swatch to make sure you're going to come out with the correct sized piece. Too many stitches/rows per inch? Try larger needles. Too few stitches/rows? Smaller needles. It grants you a peace of mind to know you're not going to create a freakish sized garment (unless the pattern is horribly written, in which place you're screwed from the get-go. Sorry about that).
What I've never seen emphasized, though, is that it gives you an example of what the fabric is going to look and feel like. I realized this in the process of making my trial XL hat, once I switched to larger needles after the brim. The fabric was far too thin for a winter cap; I could see my fingers through the stitches when holding it. It was also boring as hell; the yarn color is 'oatmeal', and on my albino-toned/tow-headed friend it would probably just blend right in to his head. If I had only made a swatch...
Snore. The photo doesn't do it justice, but trust me, my fingers are showing through the fabric.
Deep breath, no worries. It only took five years of knitting for me to come to terms with the fact that taking apart any amount of work is better than forging onward if the item is the wrong size/full of obvious mistakes/ugly. That is why I'm currently in possession of a hideous dingy yellow-colored sweater-vest, and a lovely sweater that when worn is so tight and see-through as to be illegal in most southern states. So I ripped it apart. I have a lot of wonderful green NZ merino 4-ply yarn left over from making my husband a neck gaiter for skiing (perhaps a post on that later), so I decided to beef up the size and color by holding a strand of that with the worsted weight oatmeal yarn.
My first instinct? Start in on the pattern, of course! Argh, have we learned nothing? I went through all my usual rationalizations: surely this was going to make a good fabric, these colors are great together, it will be the right size, I can just tell. After some mental gymnastics, I was resolute--make the damn swatch already!
And it was lovely.
Maybe I'll actually look up some of those cutesy things to do with swatches this time...