What is the difference between slipping a stitch ‘as if to knit’ (also called ‘knitwise’ or kw) or ‘as if to purl’ (also called ‘purlwise’ or pw)?
First of all take a good look at a few of your stitches on a needle, observe carefully which leg of the stitch is in front of the needle. For most knitters the right leg (or side) of the stitch will be in front of the needle.
To slip a stitch pw: hold the two needles tip-to-tip and allow the stitch to slither from one needle to the other. Nothing changes, other than which needle holds the stitch. The leg of the stitch in front of the needle remains unchanged.
Stitches being slipped for your own convenience, such as in mosaic stitches, slip-stitch patterns, stitches behind beads, special edge treatments or in double-knitting are slipped purlwise unless otherwise specified. The working yarn is usually held at the private side of the stitch being slipped unless it is to display a bead or form a decorative feature in your pattern (as in some slip-stitch patterns).
To slip a stitch kw: The needles approach one another at approximately 90 degrees and the needle enters the stitch just as if it were about to be knitted (to the left of the right stitch leg), and then the stitch is transferred to the new needle, this results in the stitch straddling the new needle with the left leg in front.
Slipping stitches kw makes a difference!
Stitches are slipped kw (almost always) when they are going to form part of a decrease sequence, however the abbreviation given for a decrease will usually omit any reference to this fact (such as ssk), if in any doubt consult the full definition for the full scoop!
For example, my full definition of an SSK reads:
Slip the next two sts, knitwise, one at a time, to the RHN. Insert the LHN purlwise (needle-tip to needle-tip) into both sts and knit them together. (This feels similar to working the sts through the back of loops). This produces a one-stitch, left-slanting decrease known as a ‘slip, slip, knit’.
In addition, pay attention to whether the stitches should be slipped singly or as a unit: this adjusts the sequence of the stitches.
The purpose of re-orientating and/or re-ordering the stitches is to ensure that once the full decrease manoeuver is made that desired stitch falls on top of the stacked stitches that form the decrease, with an appropriate direction of slope and usually without a visible twist at the base of the decreased stitch.
Decrease directions are customarily written assuming that you knit in ‘the standard manner ‘ – alternative knitters who may throw their yarn in the opposite direction or from their right needle to the left (or many other possible variations) will have to adapt the manoeuvrers required to achieve the desired result.
K2t (or k2tog) = a one-stitch right-slanting decrease.
Ssk (s1-k1-psso) = a one-stitch left-slanting decrease.
Remember, it doesn’t matter how you get there, it is the outcome that is important.