One of the topics during the weekend that I had chats about was about wool. And spinning.
I had the wonderful opportunity to try out quite a few different spinning wheels, both in a shop and at the conference, and one of the things that sort of caught me was the expression of "twists to an inch".
Really, folks? Twists per inch? Who wants to count that high? Plus archaeological threads never give the twists per inch - they give a spinning angle. For obvious reasons, because you do not untwist an old yarn.
A basic fact is that the historical yarns are much harder spun than what modern spinners usually do. A spinning angle of 30 to 45 degrees is quite common, and that is a lot of twist in a bit of yarn. The first time I was doing replicas of fine, historical threads, I was amazed at the high twist they had - and now I'm totally addicted to them. The soft-spun yarns that are so often to be found today are nice to wear, but they will not last for as long as a good worsted high-twist yarn. So if you are trying to spin historically and have a modern spinner's background... your wool is probably underspun.
You can measure the spinning angle by drawing a straight line on a piece of paper, then draw lines at some different angles (10, 20, 30, 45, 60 degrees) towards that line. Now you can align your thread with the first, straight line and see which of the slanted lines drawn on the paper will best match the slant of the fibres in your yarn. And if you are doing this, I'd be curious to hear what your spinning angle is in your "typical" yarn!