Why do white patches (salts) form on the surface of a stone ?

During the spring, white frost, or salt, can form on the paving. Salt can also occur on stones that have been left packed in the weather for long periods. The problem is aesthetic and does not affect the functional properties of the paving. There are different ways of removing salts. One of the possible options is to wash the salts with a water and vinegar solution. The concentration of vinegar should be fairly low; we recommend adding one (1) part vinegar to nine (9) parts water. Alternatively, the cleaning agent can also be obtained from our partner http://www.remei.com/products/detergents/.