I have a 5 yd casual 80% poly 20% wool. I wash it by dunking in a bath full of lukewarm water with just a drop of washing liquid as used in a washing machine. Let the kilt spread out in the bath and just gently press the kilt down into the water. Then rinse in cold water 4 times. Hung it up on a kilt hanger to drip dry over the bath. Do not agitate too much and do not in fact handle it much in the water. Do not ring out, let it drip dry.
When almost dry, gave it a lite pressing with a damp pressing cloth and hung up again to fully dry.

Chris.