Metal corrosion and plastic compatibility are important factors, especially in acidic cleaning. These factors should be checked when developing bathroom, coffee machine and industrial scale cleaners. The main function of acidic cleaners is the removal of hard-water salt deposits. In bathrooms, however, aggressive cleaners can also constitute a threat to the equipment itself. Both acids as well as surfactants used in cleaner formulations can cause corrosion on metals and stress-cracking of plastic surfaces. In general, surfactants are more aggressive for plastic and acids act more on metals. L(+)-lactic acid shows a very mild behavior compared with other acids on metals, as shown in the following example:

A lot of bathroom equipment is plated with a decorative layer of chromium. For example, shower bars are often made of chromium-plated brass tubes. Acids will attack the metal in time, but one to a greater extent than the other. The difference in behavior of acids can be seen in the picture below. Small pieces of shower bar were submerged 50 times in a 10% acid solution. Inorganic acids attack the metal surface much more than organic acids. The picture also shows that citric acid and PURAC are the safest. This is why PURAC is desired for bathroom, all-purpose and coffee machine cleaners, but also for industrial applications.

Compatibility of acidic cleaners with bathroom and shower equipment

Besides metal, many equipment parts in the bathroom are made from plastic nowadays. Good compatibility of an acid is essential for its durability. L(+)-lactic acid is one of the mildest organic acids on plastics as well.