SiO2-FATTY ACIDS AND TiO2-FATTY ACIDS WITH THE ROLE OF BASED HYDROPHOBIC COATINGS FOR THE PRESERVATION OF ANDESITE STONE

This study explains the preparation of self-cleaning material and preservation agent for andesite stone by consecutively layering the surface with SiO2 and fatty acid through dip coating method. SiO2 and TiO2 behaved as surface roughness agent, while palmitic acid and stearic acid were functioned to create hydrophobic layer by lowering the surface tension. The performance of the surface was defined as the hydrophobicity indicated by the contact angle formed by the water droplet. The influence of dip coating parameters was investigated including SiO2 or TiO2 and stearic acid or palmitic acid concentration, contact time, drying temperature as well as pH of hydrolysis. The highest contact angles were obtained by TiO2-stearic acid coatings with the water contact angle about 136.6 +/- 0.9 degrees. These maximum values were obtained over dip coating condition as follow: TiO2 0.04 M, stearic acid 0.16 M, 30 minutes of contact time, 95 degrees C of drying temperature and acid hydrolysis.