Here is a photo of the beginning of my sampling process. I always put on enough warp to weave a number of different weft try-outs, cut it off, wash and see which weft works the best and suits my idea of the intended purpose . Sometimes I change the end purpose based on the best weft!
This warp is 6/2 cotton, natural green, and natural brown probably sett about 16 epi. From the bottom, I wove with the brown, then the green, then tried a darker brown of another yarn (10/2 mercerized I think), then 14/4 white linen. As one can see there are two different things going on (aside from the fact that the darker brown ran in the wash!) The white linen is a much heavier yarn than the 6/2 cotton and not only didn’t shrink as much, but the thicker thread kept the warp separated more. The finer yarns drew in more and shrank more as well.
I think this was woven for the Complex Weavers Crackle Weave Study Group a number of years ago. I will have to locate my notes in the great computer filing system for more information on the sample.