Slip stitch knitting is a way of making two-colour designs using slipped stitches. It is very easy, because you never have to carry the yarn behind your work.
That single fact gives it two real advantages over conventional colourwork. The fabric does not come out thick and heavy the way stranded knitting does. And it keeps its stretchiness, which stranded work loses.
The designs can look complicated. They are not.
How it works
It is as easy as knitting a row. You work a row in one colour, and where the pattern calls for the other colour, you simply slip those stitches instead of knitting them.
Slipping a stitch means passing it from the left needle to the right without working it. The stitch below stays where it is, and its colour is carried up into the new row without any yarn being carried across the back.
That is the whole trick. You only ever use one colour per row, and the second colour appears because stitches from the previous row have been left in place.
Why it stays stretchy
In stranded colourwork, the unused yarn runs horizontally across the back of the fabric. Those strands do not stretch, so the fabric cannot either – which is why stranded mittens are warm and firm rather than elastic.
Slip stitch knitting has no strands. The fabric behind is the same as the fabric in front, so it keeps the give of ordinary knitting. For hats, cuffs and anything that needs to grip, that matters.
Practical points
Slip purlwise unless told otherwise. Slipping knitwise twists the stitch. Most patterns assume purlwise and do not always say so.
Watch where the yarn sits. Whether you hold the working yarn in front or behind while slipping changes whether a bar shows on the right side. Patterns will specify; it is the detail most often skipped.
Do not pull tight after a slipped stitch. The slipped stitch spans two rows and needs room. Pulling snug puckers the fabric.
Choosing colours
Use two colours with clear contrast in value, not just in hue. The pattern is made of one colour showing through another, and two similar tones will produce a fabric that looks vaguely textured rather than patterned.
A smooth yarn helps. The design depends on individual stitches being visible.
Where to use it
Hats, cuffs, mittens, bags and blanket panels all suit it. It is particularly good anywhere you want two colours without the weight and stiffness of stranded knitting.
It is also a very good first step into colourwork, precisely because you never manage two strands at once.
