See how the heel of the hand is larger than the other side of the palm? It's a sort of hybrid method, halfway between a regular M1 increase, where you work into the back (or front) of the horizontal strand lying between two stitches, and an EZ-style M1(bl), where you make a twisted loop around your finger and place it on the needle. See here for my tutorial on the latter method. The first type of M1 creates a tight increase perfect for when you want to close up a gap. I used it at the base of the thumb on my new gloves. The second type is ideal for those times when you don't want any extra tension on neighbouring stitches. I used it to increase in the garter stitch peplum of Harriet's Jacket. Deb's increase is halfway between these two methods. It puts less tension on the next-door stitches, which is desirable when you are increasing every row on the bias. At the same time, the fact that the twist in the stitch is coming from the loop already around the needle, instead of being made before the loop goes around the needle (as in EZ's method), gives just enough tension to keep it from being too loose.
Like the other two methods, it can be made to lean left or right. The left-leaning version is very simple. You just make a YO, then on the succeeding round, knit into the back of the YO. Done!
The right-leaning version can befuddle a knitter at first glance. Instead of making a YO, you need to make a Reverse Yarn Over. I decided to dub this RYO. Deb calls it a Lift Over or L/O. Whatever you call it, the yarn goes over the right needle to the front, then under the needle to the back, i.e. in the opposite direction to the usual YO. It looks like this.
The slightly tricky bit comes when it's time to work into the FRONT of the RYO on the next round. You need to look quite carefully at where you are sticking your needle. I use my left forefinger to separate the RYO from the stitch coming after it and to create a bit of space between the yarn and LH needle so that my RH tip has somewhere to fit.
I also found it useful, when I got to the end of the needle with the increases, to do a stitch count to check that I hadn't accidentally made an extra stitch (it can happen if the RYO rolls around and tricks you into seeing two stitches instead of one). Hard to explain, but try it out and you'll see. Once you grasp what's going on, it's easy to get it right.
The gloves are done and drying now in the afternoon sun.
Thank you, test knitters. You'll be receiving a little gift in the mail very soon. I expect to publish the pattern on Ravelry on Friday. Happy New Year! Doesn't Labour Day feel like the real start to the year?