Effect of cation addition on silica scale on glass surfaces

Mineral components in tap water generally contaminate sanitary ware. In this study, various cations (Mg, Ca, and Al) were added to an aqueous solution containing silica to prevent water stains on sanitary ware. The particle size in the aqueous solution was measured and observed to increase for all cations. To create artificial water stains, a solution containing the cations and silica was dropped onto glass and allowed to dry. When these water stains were removed by sliding, the removal rate was higher for the water stains that contained the cations. This trend was attributed to the formation of precipitates owing to the reaction of silica with the added cations in the aqueous solution. The formation of these precipitates possibly increased the particle size and brittleness of water stains owing to their sparse structure. These findings provide insights into silica-scale removal, which can improve the cleanliness of sanitary ware and reduce the frequency of maintenance.