Environmental regulations in the United States disapprove of lead in the kettle bath. Lead is either added to primary Z1 grade zinc or already contained in used secondary zinc. A third, declining method is to use low Z5 grade zinc. Steel strip can be hot-dip galvanized in a continuous line. Hot-dip galvanized steel strip (also sometimes loosely referred to as galvanized iron) is extensively used for applications requiring the strength of steel combined with the resistance to corrosion of zinc, such as roofing and walling, safety barriers, handrails, consumer appliances and automotive body parts. One common use is in metal pails. Galvanised steel is also used in most heating and cooling duct systems in buildings  Individual metal articles, such as steel girders or wrought iron gates, can be hot-dip galvanized by a process called batch galvanizing. Other modern techniques have largely replaced hot-dip for these sorts of roles. This includes "electrogalvanizing", which deposits the layer of zinc from an aqueous electrolyte by electroplating, forming a thinner and much stronger bond. In 1742, French chemist Paul Jacques Malouin described a method of coating iron by dipping it in molten zinc in a presentation to the French Royal Academy. In 1772, Luigi Galvani (Italy), for whom galvanizing was named, discovered the electrochemical process that takes place between metals during an experiment with frog legs. In 1801, Alessandro Volta furthered the research on galvanizing when he discovered the electro-potential between two metals, creating a corrosion cell. In 1836, French chemist Stanislas Sorel obtained a patent for a method of coating iron with zinc, after first cleaning it with 9% sulfuric acid (H2SO4) and fluxing it with ammonium chloride (NH4Cl). A hot-dip galvanized coating is relatively easier and cheaper to specify than an organic paint coating of equivalent corrosion protection performance. The British, European and International standard for hot-dip galvanizing is BS EN ISO 1461, which specifies a minimum coating thickness to be applied to steel in relation to the steels section thickness e.g. a steel fabrication with a section size thicker than 6 mm shall have a minimum galvanized coating thickness of 85 µm. Further performance and design information for galvanizing can be found in BS EN ISO 14713-1 and BS EN ISO 14713-2. The durability performance of a galvanized coating depends solely on the corrosion rate of the environment in which it is placed.