Fill the washing machine with warm water, (if it is too hot to put your hand in then it is too hot), Never let the water run onto the blanket!!! This will cause spot fulling. When the machine is full stop it and gently put your blanket into the water allowing it to soak up the water. Then turn on the timer again to allow the agitator to work the blanket. If you want to use some soap to clean it during this find one that is gentle and has lanolin in it. that will help the blanket to be somewhat water proof later. She suggested Dawn dishwashing soap. And only use enough to make a small amount of suds. Stay near by the washer. When the wash and first spin cycles are over and the machine stops to refill for the rinse cycle push the timer in again to stop it. Reason being not to allow the water to flow onto the blanket. Take the blanket out and then let the washer fill again. When the water stops flowing stop the timer again and put the blanket back into the washer to rinse the soap out and spin most of the water out.
Next you will need to block the blanket for this you will need a clean wooden plank longer than the blanket is wide when it is folded in half length wise. Lay the blanket on a clean surface and fold it length wise. Lay the board on one end and start rolling the blanket onto the board. Make sure to keep the edges even as you roll it, this will help the blanket to keep it's shape. Put the board and blanket in a cool dry place for about 8 hours I like to drill some holes in the ends of the plank to hang it from. Then unroll it and hang it on a line along the fold you made to block it to finish drying. The outside of the blanket will seem dry but where it has been folded on itself will still be wet. And wool will fool you and feel dry while still holding water. After it has hung long enough to feel dry you can then put it in the dryer to finish drying it and to fluff it. According to C.J. I could expect to loose about one to one and a half inches side to side and length wise. This will probably differ depending on the blanket.