Aqueous Hydrofluoric Acid (HF)
Hydrofluoric acid is a colorless, fuming solution of hydrogen fluoride in water. It is usually shipped in concentrations of 30% or 70%. Except for tantalum, glass and glass-lined piping, most materials suitable for hydrochloric acid can be used for hydrofluoric. Glass and glass-lined piping will not work since hydrofluoric acid attacks silicates of any kind. With silica (SiO2), it forms silicon tetrafluoride gas.		Density of HF-H2O solutions Specific heat Heat of dilution Normal boiling point - composition diagram Freezing points of aqueous HF acid
Hydrofluoric acid is used to polish, etch and frost glass because of this reaction. It also is used to dissolve ores, clean stone and brick, acidize oil wells, electropolish metals, clean castings and pickle copper, brass, stainless and other alloy steels, and as an alternate source of fluorine for aluminum production.