Joining Old and New Warp
I am weaving some kitchen towels and plan to tie on a new warp with different colors. I am going to tie on at the front of the loom and then pull the warp through the reed and the heddles. I have done this many times and have always cut the old warp off of the back apron rod (on the new warp side of the knots I just tied) and then tied the new warp to the back apron rod. Do I need to do this or can I just beam my new warp leaving the thrums of the old one in place? If I do this, what is the best knot to use when joining the old and the new warp?
I tie the new warp to the old warp exactly as you describe, sitting in front of the loom. The easiest and most secure knot is the overhand knot. Line up the two ends together, take their tails around and under and pull the loop closed. If you can learn the weaver’s knot, it is a very good and secure knot, maybe even better than the overhand because it is less bulky and will therefore pass a little more easily through reed and heddles. However, I’ve not been able to learn it well enough to do it as quickly as I can make an overhand knot.
Most of the time, I don’t cut off the old warp from the back apron rod and simply leave it there, so that it winds on the beam and the new warp winds on on top of it. I make sure the original knots from the apron rod and those joining the two warps don’t distort the turns of new warp around the beam by layering sticks or corrugated cardboard between the turns.
For the looms in my school, after I’ve tied on two or three times, I do cut off the older warps and retie to the back apron rod only because their buildup on the warp beam prevents winding on long new warps.