My sofa bed cover has definitely seen better days, is very grubby but too big to go in the washing machine. My plan was to take it to the launderette but having plenty of student experiences of washing coming out a bit grey, my plan was to soak it in the bath to give it a head start before taking it to the large launderette machines. Any ideas as to what would be good to soak it in. It's cream (or was originally!) & cotton. thank you!