Because I have to wet and stretch the skeins anyways, the plan for the warp yarns this time was that I add some sizing in that process, saving Silvia (who will do the weaving) from that extra prep step.

As it's here and available already, we settled on animal glue for the sizing. The idea behind sizing is to strengthen the threads against friction and abrasion on the loom, making it easier to weave and giving a better end result. So I dissolved some animal glue in warm water, bathed the skeins in their hot bath to set the twist, pressed out as much excess water as possible and gave them a good long soak (about half an hour) in the gluey liquid. 

All this was followed by the usual draining of the skeins, then stretching them and hanging them with a weight to dry. In this case, I made sure to move them frequently, especially at first, to prevent them from sticking to the drying rods.