Hi Steven. I have a client who has 9 x 100% viscose sofas in mushroom brown one in each room (its a small high end hotel/lodge) I clean these Twice a year I have always used the Chemspec extraction free quick drying shampoo mixed in a bucket of warm water. Using a a microfibre cloth put in the solution and wrung out i gently wipe all over the sofa after i have given the sofa a good vacuum first. leave for 5 minutes then towel off with a large towel. The sofa will be slightly damp and dry within 1 hour. when all sofas finished (approx 3 hrs) I go back to each one an give a light brushing with a soft hand brush. the result are always good and i have been doing this client now for 7 years. hope this helps.