If you can do a square knot you can surely do a half knot. The half knot forms a decorative spiral. As you work a sequence of knots you’ll find that you need to let it flip itself over every few knots. I started by attaching 2 (green) cords using the Lark’s Head knot onto a (pink) horizontal mounting cord.
1) Just like the square knot the outer 2 cords are the knotting cords, and the inner 2 cords are the filler cords. The difference between this knot and the square knot is that rather than alternating sides, you start each and every knot on the same side of the filler cords. Lay the rightmost cord over the filler cords horizontally forming a loop on right.
2) Take leftmost cord and place over the horizontal cord, then underneath all cords and up through loop on right.
3) Continue working the same knot on the same side for desired length. At about every 6th knot or so, you’ll notice that the spiral twist will force you to flip your work over.
4) Below are samples of how the twist differs depending on which cord you start with. The spiral on the left was worked by starting all knots with the right cord first. The spiral on the right was worked by starting all knots with the left cord first.