Since the late 1950s, platinum catalysts have been used in petroleum refineries to reform naphtha into high octane blending components for gasoline (i.e., reformates). This process is called catalytic reforming. Manufacturers of petroleum catalysts coat substrates (e.g. alumina) with platinum solutions. Palladium is used by some refiners for upgrading certain refinery feeds in a process known as hydrocracking. Iridium can also be used in conjunction with platinum in a few niche reforming applications.