Felted knitting is an amazing transformation. It is wonderful to see your big, floppy, knitted piece transform into something smaller and with definite shape. If you've never tried yarn felting before, here are some tips and couple patterns to get you started.
What is yarn felting?
Yarn felting is the process of agitating your knitting in hot water. This causes the natural fibers to expand and stick together, creating a much thicker, denser fabric where you can no longer see any individual stitches. This process will also shrink the size of the piece. Whenever you are making an item for felting you must start with a piece that is much larger before beginning the felting process. For this reason, you will often find yourself working your pre-felted piece on large needles holding two strands of worsted weight yarn together.
How to felt?
Begin with a knitted/crocheted piece that has been worked in natural animal fibers. I prefer felting with wool because I think it creates a nicer felted fabric, but also because I don't really want to spend too much on yarn that I'm felting.
Once you're ready to felt you can toss the piece into your washing machine with a couple towels (for extra agitation) and wash it on the hottest cycle you have. Stop it every 5 minutes or so to check on how well your piece is felting, to reshape, and stretch. The time needed will depend on the wool and the size of the piece but in general, about 20 minutes normally does it.
If you are without a washing machine, fill a large basin with the hottest water you can, adding a little no-rinse wool wash. Wearing rubber gloves to protect your hands, plunge your piece into the basin, rubbing it together and agitating it as much as you can. This way can take a little longer to felt but it still gets the job done. I've heard of people who felt frequently using this method often buy toilet plungers to use for the agitation, but of course, you'd want to use a brand new one!
Once your piece is fully felted you will need to get all the water out. If you are using the washing machine, run it on a drain/spin cycle. That will get all the water out and leave your piece damp. If you are using the basin method, squeeze as much water as you can out, then wrap it in a towel and tread all over the piece.
Now that your pieces are damp, you'll need to reshape them. Tugging and pulling on your piece will not harm it and will help it get into just the right shape. If you are making slipper or a bag that needs something to help it retain its shape, use plastic grocery bags for stuffing.
Place your felted items in a place with a lot of ventilation. This is important! Because the fabric is so thick, if there isn't enough air movement it will take forever to dry and can end up smelling musty.
Once your piece is fully dry, you can trim any areas that need extra shaping with scissors. I also like to trim off any extra fuzzies from the wool. You can then embellish using embroidery, buttons, or even fabric paint!