Far and away the most popular - and successful - bullet casting flux, MARVELUX has been on the market since 1971 filling the needs of knowledgeable and successful professional and hobbyist bullet casters. MARVELUX is non-corrosive to iron and steel, and does not produce fumes which can cause corrosion, as does sal-ammoniac (ammonium chloride). In fact, regular use will keep your pot free from rust! Reduces dross formation dramatically while increasing fluidity of bullet alloys, making it easier to obtain well filled-out bullets. MARVELUX is well suited to any lead alloy melt intended for casting bullets or swaging cores. Non-smoking, flameless and non-smelling. Superior to beeswax, tallow, paraffin, and other grease-type fluxes. Even better than rosin and it doesn't smell like you're burning down an old shed.