Tension in sprang is always a question. How tight should I keep my warp? Too tight and it is hard to get your hands in there to work, and strings break. Too loose and it becomes impossible to move the row just worked to the mirror image portion of the cloth. I am finding that tension also plays a role in the ‘rows per inch’ of the finished cloth. Oddly enough, a very tight tension prevents a tightly packed cloth. High tension will ‘loosen’ the cloth as you weave the next row.
Preparation work for this massive replica project included the creation of samples, using the threads that seemed right for the project. Those samples were narrower and much shorter than the finished product. Finishing the samples, and comparing them to measurements of the original sash I was concerned. The number of rows per inch was much higher in the samples than in the larger sash.
Now that I am working with a 15 ft warp, I find that high tension is mandatory. It is my only hope for keeping the threads in order, and pushing the work around to the mirror-image side. Interestingly, without working at it, the number of rows-per-inch seems to be coming out just exactly right. The amount of tension required to manage such a long warp is exactly the amount of tension to give me the right rows-per-inch. It’s looser than my sample pieces, but correct for my measurements. Go figure!