I have always had good luck by soaking then a little container of water with
laundry soap or Dawn. Let them soak, maybe stir them around a bit. Some have
soaked over night. Rinse and blot dry. Iron them while they are still a bit damp.
I haven't had to use starch as they seem to stiffen up without it but can't
imagine it would hurt.
In Off Topic, SetsetBricks writes:
Hello
How do you clean used capes and boat sails? And how do you keep them straight?
Do you place them under a dictionary?