If you cut anything off for a test piece - I would go with something like a 2 x 12 inch strip from one end - Have the 12 inch part cut on the crosswise grain -
I have cut squares off pieces and regretted doing so. I also cut a long piece off parallel with the selvage. I also regretted doing that. If you cut a piece off crosswise, you will only mess up the over-all length by not-so-much.
Some wools can be gently washed (little or no agitation) in warm (around body temperature) water and rinsed in warm water and put in a dryer long enough to get the drippy water out and then hung to dry.
Wool has little barbs on it - a bit like Velcro - and a lot of agitating will make the wool bunch up.
Also, shocking wool with drastic temperature changes when washing it will also make it shrink.
Sheep get wet and don't seem to shrink. The wool they are wearing is usually untreated, though.
Last edited by bearisgray; 10-31-2015 at 09:21 AM.