Until about ten years ago there were few, if any, products of this type on the market. Most coatings manufacturers recommended that decks and other exposed wood surfaces be cleaned before refinishing. The usual recommended cleaners were household products such as detergents for dirt removal and liquid bleach for mildew removal. Household cleaners and bleaches can be effective to some extent but they have their limitations. For example, liquid household bleach should not be mixed or used directly with ammonia or any other detergents or cleaners containing ammonia since the resulting chemical reaction can form a potentially dangerous gas.
Today there are a variety of such products available.
Each of these is discussed below. Chorine-Based Bleaches Common types of chlorine bleach used in deck cleaning products are sodium hypochlorite, calcium hypochlorite and dichloroisocyanurate. The first two are typically used in laundry detergents while the last is a swimming pool additive. When used on wood decks chlorine-based bleached products can do more harm than good. They can result in the wood's having a whitish unnatural tone due to the bleaching of natural components or a fuzzing of the wood's surface due to the loosening of small fibers during the cleaning process.