What's on the loom (the web) isn't necessarily what the cloth (web after washing) is going to be like. This is why I can't stress enough the importance of sampling.
Here's a spot bronson that I wove while it was still a web (unwashed);
Here's the spot bronson after it was turned into cloth (washed):
As you can see it is completely different!
I didn't sample here because I wasn't really all that concerned with the outcome. I'm posting this to show you that, if it matters, then sampling is an absolute must!