Big, take a small spring and hold it between your fingers, right hand on one end and left on the other. If it's wound with the wire going away from you (over the top), twist it to the right and you'll see that it wants to unwind. Twist it to the left and you'll see that it tightens up more. I think we're on the same page though
When making my strings. I put about 12 or 15 twists to the left in the material after serving the end loops. I then put as much tension on the string as my jig will allow (about 200 pounds) and then serve the end servings to the right (over hand away from me) and then do the idler and center servings, all the same direction. When the string is done I'll put it on the bow and check for length and if necessary, I'll put more twists in the string to the left (opposite the way the serving is applied).