Almost all of Stripy is going to be knit in the round. I've decided to do a false button placket at the neck because there is no need for it to function and the original one pops open occasionally, presumably because of the various button sizes, which is annoying. Of course, if you really want functioning buttons you can do that, but I think this way will be neater. Knitting both the yoke and the body in the round also avoids other potential problems such as rowing out - unevenness caused by the difference most knitters have in the tension of their knit and purl stitches which makes the gauge of flat stocking stitch different from that of stocking stitch in the round. Because of the potential for such differences it makes sense to knit your swatches in the round. They don't actually have to be knit in the round, the key point is that all of the stitches are knit stitches. You may already know this simple trick and if you do feel free to skip this part. This is also what I'm referring to when my patterns suggest swatching in the round for the most accurate results.
You can use either double pointed needles or a circular, you need to be able to slide the stitches right along the needle. The material that your needles are made from can make quite a big difference to your gauge, I know that I knit looser with bamboo than aluminum, so you want to swatch with either the same or very similar needles as you will use for the jumper. It's also not a good idea to switch needle type midway through the jumper. Unless you already know that you're a very tight or loose knitter and always need to go up or down several needle sizes the recommended size on the ball band of your yarn is a reasonable place to start. If your yarn doesn't provide this information then this chart should be helpful.
Most ball bands also give a suggested stitch gauge, to get the number of stitches to cast on multiply this number by 1.5, that should give you plenty of stitches to allow for variations in gauge and messy edges. Begin by casting on and knitting a row. Instead of turning it over to begin the next row just slide the stitches along to the other end of the needle. Carry the yarn across the back and knit the next row, I like to loop it over the back of my left hand so that it doesn't get too tight. This is just like doing i-cord except with many more stitches and you want to strand the yarn across the back rather than pulling it tight. Continue in this way until your swatch measures 5 - 6 inches and bind off normally. Cut up the back of your swatch so that it lays flat, don't worry about the ends unravelling.
Water changes most yarns and you don't want any nasty surprises when you first wash the finished jumper. So take your swatch and dunk it in some lukewarm water. Don't agitate it or anything just leave it to soak until it has properly absorbed the water, which can take a while. Then roll out the excess water with a towel and pin out the swatch to dry. There are various opinions about how much you should stretch yarn when blocking. For this I want to maintain the elasticity of the wool but I also want my gauge to reflect the amount the wool stretched in water so I pinned the wet swatch out flat without stretching it further.
Leave your swatch to dry and then you can assess whether you like the fabric, you're not aiming for any exact gauge but for a fabric that you're happy with. Unpin the swatch. Do you like how it drapes? Does it feel too sturdy? Or maybe too loose? Are there uneven stitches - I find that this is often a problem with looser gauges? Remember that generally jumpers at a tighter gauge wear better than looser ones. If you're happy with the fabric you can lay it flat and carefully measure your swatch - over 4" in the centre. If you're not happy with the fabric try repeating the process with a different needle size remembering to go down a needle size if your first one was a bit loose and up a needle size if it was too tight. This might seem like a lot of work, but I promise that by the time you have a perfectly fitting jumper in a fabric you're happy with you won't even remember the time spent swatching.
I knit two swatches, that nicely illustrate the importance of washing the swatch. I used 3.75mm and 4mm needles for my double knitting weight wool. Before washing I thought that the looser 4mm swatch was perfect, the 3.75mm one felt far too stiff. After washing the 4mm swatch felt too loose and unstructured and worse - the stitches were less even. On the other hand the tighter swatch had also loosened up - into a nice, fluid even fabric.
Make sure you make a note of your final gauge. Everything else will be worked out from these two magic numbers so check them thrice. I like to measure both stitch and row gauge at a few different points just to make sure that there is no wonkiness throwing it off. This is an especially good idea if you're using an uneven yarn, in that case you should measure several points and average them to get your working gauge. Generally, if there is a difference, the top of your swatch once you got into a rhythm will be more accurate unless you plan on being very tense while knitting the jumper! My stitch gauge is: 22 sts = 4" / 5.5 sts = 1" And my row gauge is: 32 rows = 4" / 8 rows = 1" Any questions?
The next post in this series will be about taking your measurements and I strongly recommend that you have someone to help with this. Some of the required measurements will be pretty much impossible to take accurately on yourself.