Zinsser® DIF® Liquid Concentrate Wallpaper Stripper is a biodegradable, non-toxic and non-staining wallpaper stripper which dissolves old paste fast. The 22 oz. bottle will make 2 gallons of stripper, enough to remove the wallpaper from a 12’x24’ room. The 1-gallon container will make 12 gallons of stripper. Simply add 10 oz. (1¼ cups) of concentrate to each gallon of warm water.