Vacuum the entire couch, including under all the cushions and in all the crevices, using your upholstery brush and crevice tool, to remove all loose dirt and debris.
Remove all arm covers and any removable cushion covers.
Find a place on the underside of your furniture or inside cushion cover where you can test the fabric for color-fastness.
Mix a solution of 1/2 pint triclosan in 1 gallon of water. Triclosan is the active ingredient in most liquid antibacterial household cleaners.
Drip the triclosan solution onto the area you want to test. Wait one hour and proceed if there is no color change in the fabric you tested. Add another gallon of water to the solution to reduce its strength by half if the fabric changes color, and test again.
Dip a soft-bristled floor-scrubbing brush into the triclosan solution. Shake it until it does not drip but is still damp.
Rub the brush over a small area at a time, using even, overlapping strokes. Rinse the brush after every 2-foot square area and dip it into the triclosan solution again.
Shake the brush and repeat until you have scrubbed about a third or half of the piece of furniture.
Dump the triclosan solution at the halfway point if the furniture is heavily soiled and mix a fresh solution. Finish scrubbing the furniture.
Position one or more box fans so that they blow across the furniture to help it dry faster.
Replace all cushion covers and arm protectors.
Pour 1 oz. triclosan into the steam cleaner tank and add water to the tank fill-line.
Run the steam cleaner over a 2-foot section of the furniture at a time to apply the triclosan solution.
Use suction to remove excess liquid from the upholstery.
Position box fans to blow across the furniture until it dries.
Replace all cushions and arm protectors.