Knitting with more than one colour yarn opens up all kinds of creative opportunities for knitters and the techniques are not difficult to master. Here we start with stranding, which is used for small regular repeats of different colours. It is the technique traditionally used for Fair Isle knitting.
Most Fair Isle type patterns are worked in stocking stitch. Traditionally they were knitted on circular needles so only knit rows were worked. Carrying yarn across the back of the fabric makes the rows condense slightly so knitting a tension square is even more important before you begin.
Stranding one-handed (knit stitches):
Stranding is used for small repeats of different colours worked across a maximum of four stitches. In this example the colour is changed every two stitches. On a knit row, work to where you want to introduce the new colour. Knot the new yarn around the old yarn and slide the knot right up under the last stitch.
Knit two stitches in the new colour.
Drop the (green) working yarn. Bring the (white) new yarn under the dropped yarn.
Knit two stitches in this new colour and then drop the yarn.
Take the green colour, which is now the working yarn, over the top of the dropped yarn and work the next two stitches.
Repeat this process of stranding the colours, keeping the green yarn over the top of the old yarn each time and the white yarn under the old yarn each time you change. Make sure that you stretch the stitches out on the needle slightly as you take the new yarn across the back of the stitches.
When you end the knit row the blocks of colour should have an even tension so the loops of the stitches on the needle look the same.
On the wrong side of the fabric the loops of yarn should be an even length and stranded neatly. If the loops are too tight it will make the fabric pucker.
You can make small bobbins of each yarn, one for each colour, so they do not become tangled. The finished blocks of colour should be exactly the same with no difference in tension.