Acids have a varying effect on porcelains. So, if you wonder about your bathroom sink or tub and its ability to withstand certain acids, the answer is not always clear. Some porcelains have more resistance to certain acids than others because of their coatings and finishes. Porcelain also resists some acids, but not others.
Porcelain and Acids
Acids erode materials by dissolving the chemical structure that forms the material. Strong acids wear away porcelain surfaces, cause discoloration or stain the surface a different color. The effect of the acid is not consistent on every type of porcelain, however. The strength of the acid and the porcelain itself changes exactly how the acid affects the porcelain. The pH reading of the acid is the strongest determining factor in how much it affects the porcelain.
Porcelain resists most acids aside from hydrofluoric acid. Certain processing methods give porcelain enamels the ability to resist most alkaline, salts and very strong acidic compounds and gases -- even sulfuric acid and hydrogen gas. This is not unusual, as sulfuric acid is frequently stored inside of glass, and porcelain has some of the same characteristics as glass. Additionally, the resistance to and effect of acid on porcelain is variable. By removing other properties from the porcelain through processing methods, acid resistance increases, while resistance to alkali, for instance, declines.
Extended exposure to acids may erode the surface of the porcelain, leading to extended degrees of change in the surface properties. This in turn leads to more damage. So, resistance and the effects of the solution is also dependent on exposure time. When exposure time increases with a stronger substance, the effects of the acid on porcelain is enhanced in equal terms. For instance, a tub surface contacts acidic agents for hours at a time over a number of years. The effects of the acid is therefore greater than exposure lasting only a few minutes over the course of a few days.
Porcelain in Daily Use
Porcelain uses abound in the home. Laundry machines have a porcelain enamel glaze to resist alkali cleaners. This porcelain is manufactured more to resist alkali solutions than acids, however. Exposure to acid will damage the surface faster than porcelain made to resist acid specifically. Porcelain enamels cover sink surfaces, toilets, tubs and even small electrical transistors.