Caustic soda, also known as sodium hydroxide and lye, is created during the same process of making chlorine. It is the principal strong base used in chemical applications. In most cases, the base is purchased as a 50% liquid solution. However, it is also available in dry forms such as pellets and granules. In its liquid form, it is both odorless and colorless. Dry forms tend to appear white in color.
Lye is highly corrosive and highly reactive in all forms. This is why it is so commonly used in the chemical industry. It is used primarily in the manufacture of organic compounds. At the same time, the base is also used when making paints, glass, ceramics and even cosmetics and soap. Paper mills use it to break down pulp and cellulose.
While the product is stable, its shelf life can vary widely based on storage conditions. It should be kept in a temperature controlled environment, and stored in an airtight container. When it is exposed to air, caustic degrades in quality quickly. Eventually, sodium carbonate solids will form, and the caustic will become unusable.