Deionized Water System: Deionization is a method used most often by laboratories to produce purified water on demand. All naturally-occurring water contains dissolved mineral salts. In solution, salts separate into positively-charged cations and negatively-charged anions. Deionization can reduce the amounts of these ions to very low levels through the process of ion exchange. Cations are removed by cation exchange resin. It replaces sodium, calcium, magnesium, and other cations with hydrogen ions (H+). This exchange produces acids which must be removed or neutralized by anion exchange resin. This is also why you must not use the system outside of its operating parameters or you could cause damage to your work surface. A true spotless and waterless rinse.