This was my first attempt at felting. The swatches on the left were not felted, those on the right were felted. I know it's not a close-up shot, but you can probably see that there is not a lot of difference in stitch definition between the two sets. I had hoped to accomplish a near total loss of stitch definition. I felted the swatches for 20 min in the washer. I think the problem was that the water in my washer wasn't hot enough. I set it on "warm", but got water that was maybe slightly warmer than tap water. Every water source in our house seems to take a long time to warm up. Even though the washer is just on the other side of a wall from the hot water heater, it apparently has the same problem. I guess next time I'll have to try it on hot. The felted swatches have also been blocked, so they lie flatter than the others. I also made two swatches each with hook sizes H, I, and J to see how the stiffness/drape of the fabric would be with those differences. I felted one of each. Interestingly, the felting seem to pretty well equalize the difference, so that all the felted swatches have about the same drape.
In order to felt you have to start with a yarn that is at least partially animal fiber. Other fibers don't felt. I used Louet's Riverstone (100 % wool). You need friction, warm to hot water, and plain soap, such as Ivory dish soap. You can do this by hand and rub the material in the water, or you can do this in your washing machine by placing other items in the wash that are similarly colored. I found some good felting instructions by searching the Lion Brand yarn website.
I hope to eventually design a felted garment with this yarn, but obviously, I'm going to need more practice. I need to be able to consistently get the results that I want and a predictable amount of shrinkage. Then I'll have to be able to tell others how to get the same results.