Shadow knitting, or illusion knitting, is a process of knitting such that the finished piece has a hidden image only viewable from an angle. The effect is created by alternating rows of two colored yarns so that the raised stitches from one row block out the flat stitches of another row. The finished work looks like a simple striped pattern from the front, but when viewed from an angle, the "hidden" image appears.
The first image is a piano keyboard pattern that I knitted. The second and third are a simple block pattern for this instructable viewed straight on and then at an angle.
Step 1: Gathering Materials and Creating a pattern
This process relies on raised stitches, so worsted or sweater weight yarns work best. Homespun yarns or yarns that have irregular shapes do not work as well.
You will need two contrasting colors, usually a light and a dark work best.
To create the pattern you will need graph paper or a spreadsheet program like Microsoft Excel. For the sake of this instruction set, I have created a simple block pattern that is 20 stitches wide and 6 stitches high, repeated indefinitely.
After the basic pattern has been created choose which of your two yarn colors you will start with. This will be your "background color" The other color will be the "pattern color". We'll call them "Color 1" and "Color 2". For this set Color 1 will be white and Color 2 will be blue.
The trick to shadow knitting is in reading the pattern. Each single row in the pattern represents 4 knitted rows.
Row 1a - Color 1 - Knit across
Row 1b - Color 1 - Knit and Purl in pattern
Row 1c - Color 2 - Knit Across
Row 1d - Color 2 - Knit and Purl in Pattern
Step 2: Casting On and Beginning Row 1a
Using Color 1, cast on the number of stitches in your pattern.
Step 3: Row 1b - Knit and Purl in pattern
Follow the pattern knitting where the squares are white and purling where the stitches are black. Since we are on the "wrong side" of the fabric, this will create raised stitches where you knit and a stockinette stitch where you purl.
Looking at the pattern, it shows the first five stitches are Color 1, The next five are Color 2, five of Color 1, five of Color 2. In the first picture I have knitted the first five stitches. To switch between, I move the yarn from the back of the work between the needles to the front so that it looks like the second picture.
Step 4: Row 1c - Introducing Color 2
Switch to Color 2 without cutting Color 1. Knit across in Color 2.
Step 5: Row 1d - Knit and Purl in pattern.
Remember, this is still "Row 1" of the pattern. This is essentially the opposite of Step 3. In Color 2, you will purl where the blocks are white and knit where they are black.
Once you finish with this, bring Color 1 up behind the work and start your next knit row. This is the start of Row 2a.
Step 6: Continuing the work...
Continue to work in the same fashion:
Row a - Color 1 - Knit Across
Row b - Color 1 - Knit on the white pattern blocks, purl on the black pattern blocks
Row c - Color 2 - Knit Across
Row d - Color 3 - Purl on the white pattern blocks, Knit on the black pattern blocks
This picture shows rows 1-6 of the initial pattern.
Step 7: Step back and admire your work
During the process, you can gauge how your work is going by looking down the piece at an angle.
Once your pattern is done, or you are happy with the length of the piece, bind off as normal once you have finished a 'd' row with Color 2.