Wool Content Necessary for Felting Yarn?

I assume you are referring to wet felting, which involves washing the wool in hot water so it becomes thicker and tighter. Wet felting requires 100 percent wool. Any other fiber will keep the wool from shrinking the way you want it to.

There is a method of felting called "needle felting". The extreemly sharp needles have hooks on them and they grab the fibers and interlock them. Can be used on most all spun fibers. Get a kit at a yarn shop. It will give you sugestions on what to use under the fabric to catch the needles. I use an old piece of foam rubber about 4 inches thick. Remember, no little kids under 14 near the needles.

Oh! I was thinking about the needles so much forgot to mention that some wool will not felt with the water method as it is super wash. I don't know much about it except it is sold for spinning.