Sampling for a Wide Warp
My question stems from problems I have had when weaving a sample. How do you sample for sett on a wide warp, for example 36" or 40" wide? My experience has been that a narrow sample isn't really an accurate sample for a wide woven piece. The sett looks fine on the small sample, but when warped and woven in a wider width, the weave turns out much looser than the one sampled. For example, I wove a sample of 10/2 pearl cotton 10" wide in a huck lace weave at 20 epi, which looked perfect when washed, but when translated to a 36" wide warp, looked too loose, and it seemed like 24 epi would have been better. Several times I have even re-sleyed for a closer sett when the wider warp seemed too loose, but that is a lot of extra work. Perhaps you have solved this problem?
I think that you are perhaps ascribing the wrong reasons to your observation that the wider piece ends up being looser. When you beat, you are actually applying force to the fell of the cloth. I was a physics major for a semester in college until I realized—er, well for one thing, I didn't have as big a slide rule as all the other majors—so I remember a few formulas. An important one for weaving has been: force equals mass times acceleration. This means that when you beat, the mass of the beater and the speed with which it hits the fell determine how closely you can beat in the weft relative to the density and number of warp threads.
Therefore the more warp threads you have and the closer they are together the more mass/acceleration you are going to need to accomplish the same weft sett. If you weave a sample at 10" width and then weave the fabric at 30" width, you are going to have to up the acceleration to get the same weft density. In cases where you are trying for a dense weft sett, sometimes this can't be done.
Huck lace in 10/2 pearl cotton at 20 ends per inch should be woven with 20 picks per inch, no matter how wide the cloth. Really, your 10" sample was sett too open (10/2 usually works best at 24 ends per inch). You actually should be able to beat in 10/2 pearl cotton at 24 ends/24 picks per inch at any warp width, whether narrow or wide; it just takes practice with your beater and loom and careful measurement.
But for pieces that do need some forceful beating for a closer weft sett, I never sample with a narrow warp width. I like to put on an extra yard or more and sample with the actual warp width. If I do discover a need to change the sett of the warp (which would be to make it more open, i.e., fewer ends per inch, if I needed to beat in more picks per inch), I just change the sett of the warp and start over.