Navajo plying is a handy way to ply when you only have one bobbin of yarn spun. It creates a 3-ply yarn from a single strand. As always with plying, you will want to ply in the direction opposite the direction of your spun single, usually "S" for plying.
To begin, place your full bobbin on your lazy kate. You'll find it easier to control your yarn if your lazy kate is placed on the same side as your forward hand. In my case, I always spin with my left hand forward. So these directions will be written from that perspective. Feel free to work in the way that is easiest for you.
Make a loop at the end of your leader, and another loop of about 6" or 8" at the end of your single to be plied.
1. Place the loop of your single through the loop at the end of your leader, pulling it through to the point where your knot is at the loop of your leader. You now have a loop of 6" or 8" hanging from one side of your leader, and your single strand on the other side.
2. Open the loop with your right hand, and bring the single strand through it forming another loop, pulling it to about 6" or 8" long as you begin treadling.
You'll be holding the loops with your right hand, and controling the single with the left. You want to keep even tension on the loop and your single.
Be sure your new loop is pulled through before the twist enters the place where the two loops intersect.
Continue this process of forming chain loops until the bobbin on your lazy kate is empty.
A Tip For Smooth Joins Between Loops
As the twist enters the place where two loops intersect, you should be holding your single in your left hand so that the single is positioned over your index finger as it goes toward the wheel. Keep your index finger slightly under the loop held in your right hand, so that the join will roll over the side of your index finger as the twist joins the single to the loop. Placing tension on the single while it slips under the loop as it twists will create a smoother join. This may sound complicated, but is really very simple as you do it.