Oxyacetylene in use to cut through mild steel plate. Acetylene is used both to cut & to weld steels. Its flame burns hot enough to melt metals & is neutral, which means it burns without leaving oxides (rust") in the weld region. The acetylene burns in two stages; close to the torch, where the two gases mix, it burns to carbon monoxide. This reaction provides the heat for melting the metal. Away from the torch the carbon monoxide burns in oxygen from the air to give the blue flame. A special use for oxyacetylene is the welding of cast iron. Protection (goggles & gloves) is against the shower of sparks rather than fumes or ultraviolet light as in other forms of welding."