My friend Rob likes to go out rowing even in the middle of winter. And it's not exactly balmy out on the water around Vancouver, so he could use a nice hat. A hat of lofty, warm yarn would not stand up to daily abuse and one of firm yarn would have fewer air spaces to trap heat. To keep his head warm in damp and windy conditions, I combined a firmly knitted shell with a soft inner lining. Wool is the material of choice, because it insulates even when it is wet.
But I didn't want to do a completely double layer reversible hat, because that would make the hem bulky as well. The hem should be thin, with ribbing to help hold the hat on without catching in the wind. The answer is to insert a second layer of knit fabric above the hem.
Here are some images
I spun two different yarns, one firm and one soft, to make the layers. I did some swatches to determine the number of stitches required for each to make the correct size, knit the lining, then started the shell and inserted the lining a few rows after completing the ribbed hem. Before completing the shell, I fastened the loose ends. I didn't need to completely darn them into the fabric, because they are enclosed inside the lining.
The lining is knit the same as the shell, except it's only the top part. Start with a provisional cast-on to have ready loops to pick up later for the joining row. Any basic pattern for a knitted in the round hat will do, and the only tricky part is joining the two layers. If you have one you like already, then see the section below on joining. Or you can follow what I did and design your own great hat.
The lining and shell serve different purposes, so the yarns must also be designed with different tasks in mind. Both yarns were spun from wool top, hand combed from raw fleece. Different amounts of twist and different drafting techniques make one firm and the other soft from the same type of preparation.
This single was a little smaller, with a worsted draw and more twist. At about the same m/kg, it's a smaller yarn even as a three ply. I attempted to ply from both ends of a center pull ball plus one from a bobbin and I don't recommend this. It might be ok for a small sample but the tension is hard to control and the the two ends from the ball want to twist themselves, leaving the other out. With some effort I got a usable yarn, but it is not perfectly plied. I spun 110 g but only used about 90, or around 175 m. Yes, handspun yarn usually weighs more than a similar looking commercial yarn. It's like that fancy ice cream: more stuff, less air.
From my gauge swatch, I needed 116 stitches with a size 5 needle to get the size I wanted. I cast on and did a few rows in waste yarn and then attached the lining yarn. Leave a really long tail, enough for three or four rows, and fold it up with a safety pin to keep it out of the way. You will need it later to pick up and knit the joining row.
I should have done a real provisional cast-on that would rip out easily later, but I forgot. So I did the extra rows in waste yarn and cut it out instead. I should have left a longer tail, too, because I had to rip back a row to get enough. But, hey, this is a prototype.
I knit round and round for 12 cm before starting the crown shaping. I did evenly spaced decreases, 8 per round, until there were about 48 stitches remaining. (I didn't count.) At this point it gets small enough that 8 decreases per round are too many, so I cut back to 4 and skipped a round entirely about one out of three. There isn't a real pattern to follow here, I just did it so that it seemed to be progressing towards the center at the right speed. Too many decreases and it gets too small too quickly, putting stress on the stitches. Too few and it doesn't lie flat nicely. There's nothing special about my method and any pattern that makes a nice rounded crown works just fine.
When that's all done, take out the cast-on, rip the waste yarn and pick up stitches onto another needle. Then knit one row REALLY HUGE. I mean it. You can do it very loosely or with a big needle or wrap the yarn a few times, however you like. But this row should be about three times taller than normal, that's why there is all the extra yarn. It gives enough slack to fold the lining into place and have it stay flat, otherwise it would want to hang down instead of stay inside the hat.
Ok, here's the scary part. There's math involved, and there might even be some bits that will just be a guess. I'm not used to either writing or following patterns, so when I did this, I would write out a set of directions and then attempt to follow them. It took several tries to get it right, so if you make a mistake then it doesn't mean you are an idiot. Try not to, because taking it all back out is a big pain. Trust me on that one. Just remember one thing: the join is hidden inside the hat and nobody will ever see the lining except you and the wearer. So if it's off by a bit here or there it's not a complete disaster.
The theory here is just like a regular hem, except the number of stitches is off because it's two different pieces. Normally you would just pair them up and knit two together, one from each. With 138 body stitches and 116 lining stitches, there's 22 extras that have to fit in someplace. 116 pairs divided by 22 gives 5 and 6/22 repeats. That's a pretty weird number, so start with 5 pairs per repeat as an "initial guess."
That gives the pattern BL BL BL BL BL B, or one extra body stitch for each five pairs and uses six body stitches for every five in the lining. 138 divided by 6 is 23 exactly, but 116 divided by 23 leaves one extra. Stick that one in at the center back and don't worry about it. If you get more extra than I did, evenly space them as best as possible but don't get all worked up about it because it's not that big a deal. To confirm that your pattern is correct, multiply the number of Bs and Ls in each repeat by the number of repeats and add the extra stitches. You should get your exact stitch counts for both body and lining.
Once you figure out your pattern of body and lining stitches, write that down on a piece of paper so you don't forget. And go get a cup of tea. If you don't like math very much you will probably want something about this point.
When you get back, put the lining inside the ribbing with needles together and the purl side of the body touching the knit side of the lining. When the lining is folded back up into the completed hat, then the knit side will show. With another circular needle, slip stitches from both in the pattern you determined earlier. Take it slowly to make sure you get the pattern correct. On the next round, knit your body stitch plus a lining stitch together as you come to them.
Continue knitting the body as usual, with the lining folded down out of the way. After the joining row, the body is knit exactly the same as the lining. Trim all the loose ends to about 3 cm before you start the crown decreases, but there's no need to darn them in. That's one of the great things about linings, all those ends are hidden. And with a wool yarn, they aren't likely to come undone, either. At the very end, fasten off the tail and pull it inside with a needle or crochet hook.
Stuff the lining up into the body, tugging a bit at the joining row so those huge stitches you made give enough slack for the lining to lie flat.
Now give it to your adoring, grateful recipient and bask in the accolades. Or wear it yourself and admire it regularly. And start planning the next project!