Laboratory glassware and instruments may be washed by hand or using specifically-designed washing machines or washers. Laboratory glassware washing machines and detergents are designed to clean all types of soil.
In most cases, glassware or instrument cleaning is performed in 3 steps:
Pre-wash This is used if impurities are strongly adhering to the items to be washed. Pre-was is especially important when cleaning stainless steel instruments that have been in contact with corrosive fluids such as blood or saline solution.
Wash Water is used to dissolve detergents and provide mechanical force for the cleaning process. Hard water decreases detergent cleaning efficiency, therefore, the use of softened or purified water is often recommended.
Rinsing It is important that no detergent residues remain on the items being cleaned, as they may interfere with the experiments being conducted with these items. Therefore, rinsing is a very important step of the washing process. In addition, as the water used for the final rinse is allowed to dry, the salts naturally present in the water droplets become more concentrated, increasing the risk of discoloration, corrosion or the formation of “water spots.” It is usually recommended to use purified water for the final rinse, regardless of whether it is preformed by hand or by a machine.