1. Pull the bobbin down to maintain tension on the thread. Press the back of your right index and middle finger against the thread. (You may press the bottom of the two fingers against the thread, with your index finger below your middle finger. Try both methods, and see which you prefer.)
2. Loop the thread around your fingers. slightly bend your index finger, and hook the thread around the finger. Draw the bobbin toward the left, and position the apex of the triangle against the hook. (If you started with the bottom of your fingers against the thread, flip your hand over and reverse the position of the fingers when you pull the thread up in front of you. Now your fingers and thread are in the same position as seen in the photograph.)
3. Continue to maintain tension on the bobbin with your left hand. Twirl your index and middle fingers inside the loop, wrapping thread around the hook and standing thread. Important: do not wrap the standing thread leading to the bobbin around the hook. The goal is to make four or five wraps of thread over the standing thread; you must bind the standing thread against the hook. Here’s another important point: The hook eye must remain inside the triangular loop of thread.
4. We’re ready to tighten the knot. Continue to maintain tension on the bobbin. The thread is looped around your index finger on top of the fly. Now press your fourth “ring” finger against the knot; this will hold the wraps of thread in position while you complete the whip-finish. Grasp the thread loop with your index finger and thumb, and begin pulling the bobbin down. Lower your thumb and index finger to the hook as the noose tightens. Give the bobbin a gentle snap to pull the thread from your fingers and tighten the knot. Now you may clip the thread.