patented a water borne leach-resistant borate preservative formulation that contains ammonium or sodium borate, a source of co-biocide metal zinc and/or copper (metal oxide, metal carbonate or metal hydroxide), a volatile organic acid (formic, acetic or propionic acid), free ammonia, and ammonium salts to aid dissolution. In order to achieve a high concentration of metals and borate, it is necessary to use high concentrations of ammonia, resulting in excessive ammonia volatility and noxious fumes, creating undesirable worker exposure problems in large-scale operations
and encouraging mold growth on treated timber.