Protective effect of TiF(4) solutions with different concentrations and pH on development of erosion-like lesions.

To evaluate how concentration and pH of TiF(4) influence the erosion-protective effect. Specimens were treated with a TiF(4) solution: (1) 0.5 M F, pH 1.2, (2) 0.05 M F, pH 2.1, (3) 0.5 M F, pH 2.1, or (4) 0.05 M F, pH 1.2; then, they were exposed to HCl. After 2 min, the proportions of the area covered with the coating were 93, 71, 17 and 0% in groups 1-4. When present, the coating seemed to protect the surface. After 6 min, a coating could only be seen in group 1 (43%). Reducing the concentration of TiF(4) and increasing the pH of the solution decreased the protective effect.