Does anyone know the knot to use when tying the loose end of a thread. Tough for me to keep it from unraveling.

Are you talking about inbetween steps, or finishing the head of the fly? There is the "halfhitch" knot between steps. I always do this to keep a section from unraveling either between tying steps or if a fish shatters a fly. When I'm finishing a fly, on the head I do a whipfinish. If you've ever wrapped oars, it's similar. You basically wrap the thread over itself to finish up the head. That way their is no tag hanging off head of fly. If you're in/near the Tacoma area, I'd gladly show you how to do both knots.

Thanks '69

I'm not really tying for flys (yet), I'm dressing up my spinner collection with yak hair and luminescent green synthetic material used in streamers.

Its difficult to get the synthetic stuff to distribute evenly around the yak hair and get it wrapped and tied off, looking nice.

So far the fish don't seem to mind how nicely its prepared.