Lye water is basically a mixture of sodium hydroxide and water. The reason behind pre-mixing these ingredients is to ensure a complete reaction when adding it to the soap making oils. In all instances, appropriate safety equipment (goggles and gloves at a minimum) should be worn. This could save you a loss of pain or even your eyesight.
The more common name for sodium hydroxide is Caustic Soda and is generally available at most hardware stores.
