Hydrogen Fluoride (HF) is a colorless gas. Hydrogen Fluoride in the liquid form is Hydrofluoric Acid. Hydrogen Fluoride emissions are present across a variety of industries including metal processing and finishing, agricultural, fertilizer, semiconductor, chemical production, and mining. HF is widely used in stainless steel and alloy industries for pickling and descaling various metals. HF is often used in the chemical etching process of aerospace components.