|My first mosaic project|
Sometime later I started to become aware of how I was slipping the stitches. I'm certain at first I always slipped knit wise. This was the slip direction that I used in the left leaning decrease, slip, slip, knit (SSK) so I think I just didn't even reason out that the stitches could also be slipped purl wise. At some point, I must have read something in Barbara G Walkers stitch treasuries that introduced the concept of slipping purl wise to avoid twisting the stitch - and then I had another Ah Ha moment. I discovered the concept of stitch mount.
If you look closely at a row of stitches on a left needle, you will see that the yarn sits over the top of the needle at an angle, not directly perpendicular to the needle. One leg is closer to the tip of the needle than the other. If the front leg, the leg closest to you, is closer to the tip of the left needle, then this stitch is mounted in the traditional western stitch orientation. To keep a stitch in this same orientation while slipping it, it must be slipped purl wise. Or to state it another way, insert the right needle tip into the front leg of the next stitch as if you were going to purl it, but instead of wrapping the yarn, just move the stitch to the right needle with out working it.
I've seen some rules bandied about explaining when to slip knit wise or purl wise. The most common one is to slip the stitch knit wise if it is going to be worked again on the same row (as in a decrease like the ssk) and to slip purl wise if the stitch is not going to be worked again until the next row. I think there are probably a few exceptions to this rule. And rules can sometimes keep you from discovery. So the next time you encounter a slip stitch where the designer doesn't specify how to slip that stitch - just give it a try either way, and decide for yourself which you prefer.
Happy New Year - may 2012 bring you many knitting adventures.