1. The rust on the surface is a small amount of iron residue left on the surface after contacting with iron substance in the process of mining, processing, transportation and installation of stone. These residues react with air and water to form rust.
2. Deep rust is a special kind of stone, which contains a certain proportion of iron components, such as some granite, slate, American white hemp, Shandong white hemp. These iron components will also breed rust when exposed to air and water.
3. In addition, under the action of water, alkaline substances in cement will react with iron in stone to form rust.
Conclusion: the air humidity in South China is relatively high, and the texture of Yashi white stone contains certain iron components. The iron components react with water and oxidation to form rust and rust spots. Another reason is that the cement mortar is wet pasted, and the alkaline substances in the cement are immersed from the back of the stone, and the rust spots are formed by the interaction of the iron components of the stone itself.
Treatment: use professional stone rust remover to clean the stone surface.