52 Weeks, 52 Hats: My highly derivative method for making a hemmed hat

Back in early April, one of my Ravelry friends asked how I made the hemmed edge for my Giant Snowflake Hat-- I started to write her a rather long-winded reply before deciding that I might as well turn it into a blog post. I feel a bit like I'm standing on the shoulders of giants here-- TECHknitter (as usual) has a great series on better bands and facings, including a post on sewn hems, and I've also picked up quite a few tricks from Knitting Without Tears and Knitting in Plain English. So I hesitate to call this a tutorial... hence the post title.

There are a few good reasons for making a hemmed hat:

It looks pretty and doesn't curl.
The doubled fabric makes an exceptionally warm layer over one's ears.
For the wool-sensitive, the lining can be made from a less irritating fiber-- no more prickly forehead.
It's perfect for all-over color patterns where another type of border would be out of place-- or for large motifs that would be too large to allow for another border.

That said, the first time I made a hat that called for a hem, I found it a daunting process... in fact, it still daunts me a tiny bit, though less so each time. This is the process I usually follow for a basic hemmed hat:

1. Start with a provisional cast-on. This is my favorite method-- you'll need a crochet hook. Using waste yarn (or cotton crochet thread, which I prefer), cast on the number of stitches needed for body of your hat. THIS IS IMPORTANT: after you pull the end of the waste yarn through the last stitch of the chain, tie a couple of knots in it-- you need to know which end is which. Join your working yarn, knit across the row, then join to work in the round. Now, knit one round plain, then purl one round. The purl round is important because it gives a horizontal crease line that will enable the hem to fold over neatly. It will look awesome.

Here's the edge of that hat with the provisional crochet cast-on-- note the knots!

2. When you are finished knitting your hat-- which, if you are me, and you're doing battle with a colorwork pattern, may take a while-- go back to your provisional cast on. You'll notice a couple of things:

One side looks like a crochet chain-- which it is.

As for the other side-- those blue loops are soon-to-be live stitches!

The beauty of the provisional crochet cast on is that it can be easily, yet carefully, undone one stitch at a time, starting at the end of the chain (you did remember to tie knots in that end, right?):

Place each live stitch onto a circular needle as you go.

3. Once you have all the live stitches on your needle, the fun really begins. You can knit your lining in a contrasting color-- or knit color patterns or an inscription to the recipient or lines of poetry into it. You can use up annoying little bits of leftover yarn-- or maybe a stray bit of cashmere... Whatever you do, one rule to follow is to make it less bulky than the outer hat-- decrease the number of stitches by 10-20%, use thinner yarn, do BOTH if you're feeling crazy. A slimmer lining = a hem that is less likely to flare-- and you know how I feel about hem flare.

Another trick-- work the facing in 1x1 ribbing-- it will reduce bulk and give the edge just the right amount of grip.

4. Make your lining at least 2-3" wide, then... DO NOT CAST OFF! The point of making your hem this way is to have the least possible amount of binding at the edge, and to make it nearly invisible from the outside. So you are going to tack each individual live stitch to the inside of the hat. Start by transferring all of the live stitches to a length of waste yarn. Cut the working yarn to a length 3-4 times the circumference of the hat. Then, turn the hat inside out and fold the facing into place: