Waistcoat stitch in rounds and rows
The waistcoat stitch (WST) is also known by some as the "knit" stitch or "centre post" stitch. When worked up you get something that looks like knitted stockinette stitch. Because you work into the post of the stitch, the resulting WST all stack up neatly on top of each other.
I can't remember how I first learned about the waistcoat stitch but I was excited that there was a stitch that made crochet look like knitting. Sadly, I also remember is that my early attempts at doing this stitch were a bit of a failure even though it is a fairly easy stitch to do. One of the reasons I think I failed initially was that I didn't read the instructions properly. I had been looking at the instructions for working in rounds and then trying to work the WST in rows. This blog post is not really a "how to" for doing this stitch but also more a collection of some of my thoughts on how I figured things out for working with this stitch. I've tried to write this post several times, so this is the result of several attempts and, hopefully, it will all make sense to whoever takes the time to read it.
The short version
The short version (before I go into more detail) is that you work your stitches like a normal single crochet (or hdc or dc) except that you insert your hook into the post of the stitch instead of the space. You need to make sure you have a relaxed tension in your stitches or you will struggle to work into the posts of the stitches.
The longer version
While working in rounds (particularly continuous ones) is relatively simple, working in rows can be a little more confusing. When you are working into the space made by a stitch you don't really have to think about what the post of the stitch looks like. However, if you are working the WST then the way the post looks depends on which side of your work you are looking at. If you are working in continuous rounds then the right side is always going to look the same (see photo below) and you end up with the post looking like a "V" every single time. This makes it relatively easy to work this stitch in rounds.
However, if you are working in rows then you are looking into the back of the stitches you made in the previous row. In this case, you will see an upside down "V" with a couple of lines at the top of it (see photo below).
There is also a difference in what you see at the beginning of a row since the post is made up of parts of 2 adjacent stitches and therefore the last stitch of a round does not look like an upside down V at all. You can see this in the photo below the first stitch looks different to the rest of the stitches in the row (kind of as if half of the post is missing).
I think this was what I found most confusing about trying to work this stitch. I looked at a few videos and photo tutorials and very few of them actually showed how to begin or end each round (they mostly began the tutorial or video in the middle of a row). After trying a couple of ways of doing my stitches (including finally finding a video where someone explained how they began and ended rows of WST), I realised that there are a couple of ways people do the WST in rows (all the photo tutorials and videos had been using either one or the other method).
The first method is the obvious way of doing things where you strictly go into the post of the last stitch of your previous row even though it does not look like the other stitches. This means that the first stitch is tricky to work. However, the rest of the stitches all look identical. While I was trying to figure out how to do the first stitch this way, I sometimes turned my work to make sure I was going through the V on the other side of the row as you can see in the photo below:
The photo below shows several rows worked in WST in this way:
Another way to do things is to work your first stitch into the first upside down "V" ie the second to last stitch of the previous round (see photo below the hook is showing which post to work the first stitch into).
This might seem like a silly thing to do as, in theory, you will not have enough stitches in your row. However, if you're doing things this way then you make your last stitch into your turning chain. You might think that this method would leave your work looking lop-sided or give you jagged edges. However, it is actually the opposite. If you are working strictly into the posts of the stitches in your previous row, you will end up with a jagged edge (as you can see in the earlier photo of the orange swatch). However, if you skip the last stitch of the previous row and work into the second stitch (ie the first stitch post that looks like an upside down "V") and your last stitch into the turning chain, then you will end up with much straighter edges as you can see in the photo below.
I hope you have found my thoughts on this stitch helpful.
After talking to the friend who tested a pattern using this stitch that I'll be sharing later, I realised that I wasn't the only person who struggled to figure out how to do the waistcoat stitch. My friend made a small swatch in the round and quite possibly invented a whole new stitch in the process. The only instruction I gave her on how to do the stitch was to insert your hook into the post, pull through a loop, yarn over and pull through 2 loops. She interpreted that as insert your hook into the stitch as you normally would, then insert it through the back of the post and pull through a loop, yarn over and pull through 2 loops.
I think the end result kind of looked like purl stitches on the right side and front post stitches on the wrong side. However, as she was doing it in the round it was a little tricky to figure out. I think if you were going to name the stitch you'd call it a half front post single crochet.
I tried her method in rows to see if it gave me a purl-like stitch. The result was rather interesting but did not look like a purl stitch. I think it kind of looked more like the camel stitch or a bunch of front post stitches (probably more the latter) which give a kind of brioche knit look to the fabric (more on brioche knit-like stitches at a later date).
Thinking about it, I know when I was trying to work this stitch I worked out that the post was where you put your hook but hadn't relaxed my tension enough to get my hook through the post so I used the hook at the end to twist the post and ended up with a crazy looking stitch too. Sadly, I don't think my early versions looked quite as cool as my friend's version.