I learn a lot of things from a lot of places, and I can't remember where I learned this. My apologies if I learned it on this board and just forgot. I use it all the time when hand stitching anything like bindings to keep my needle from coming unthreaded repeatedly. The recent topic of dryer sheets for knot prevention reminded me of this, and of the "quilter's knot" that I use at the long end of the thread.
needle knot drawing
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