Well, I was gonna answer your Q about the thread, Del, and then I realized you said "crocheting"; "DOH!", I read embroidery, for some reason or other.

My Grandma who did most of the crocheting in our family, used anything she could get her hands on. The stuff I remember her using for dishcloths was just cotton yarn, and it had some size number. Beyond that, I ain't any help at all.
An anecdote about heavy bedroll quilts: I used to have one that I carried around in a GI duffel bag in the trunk of my car, that was made from surplus military blankets of several colors, that had been cut into squares and strips, and pieced together with some sort of heavy thread. It was three layers thick, and tied, rather than sewn - my Mother-in-law called it a "comfort", meaning comforter, I'm sure. That thing was heavy, and about the size of a queen sized blanket. I put some buttons and string loops on it to make a "bag". What they say about wool keeping you warm, even if it gets wet, is true; I spent a wet night in that thing, wrapped up in a tarp. It got wet inside, but I never got cold, until I crawled out of it. It went "down the road" somewhere in the years past; I haven't a clue as to what happened to it.