Knitted Felt

[kochi~mochi]

As far as i know, you have to use some percentage wool. I know that if it says that its machine washable, it won't work.  

[Catcheen]

Acrylic is plastic. Plastic will not felt. Plastic will melt, though!

Wool felts because it's hair. Hair that has barbs. When you felt, you're opening those barbs, agitating and locking them together, and closing the barbs in the cold water rinse. Alpaca, angora, mohair, and wool will all felt.

Cotton, bamboo, soy, those are all plant materials and will not felt. Silk is an animal material, but not hair. Silk also will not felt.

You need at least 80% wool to get a decent felt going. Between 50% and 80% will only give you a partial felt. Anything less might not show any noticeable difference.  

[Catcheen]

kochi~mochi

As far as i know, you have to use some percentage wool. I know that if it says that its machine washable, it won't work.

Yes, superwash wool has been treated with a chemical that burns off the barbs thus preventing any felting. This type of wool is safe for machine washing.  

[Supertheory]

It won't, but acrylic yarn is icky anyways.