I probably learnt one of the most important things of my weaving career. Tension of the warp. When I started I used to ask and ask and pester - how do you know how tight to tension the warp. In the end I was told just keep tensioning until the shuttle stops falling through the warp! Not so.
When weaving with merino it should be loose enough to be able to press your knuckles into the fabric slightly. It might only be the difference of one click of the ratchet. This gives the threads somewhere to move when tension is released.
Thanks Margaret for that gem. I'm going to have to revisit other types of warp as well.