Deterioration of the stone due to soluble salts depends of the stone structure and on ambient conditions and it can be described as follows:

Pre-mix the compound with deionized water around 8 hours before application (max conductivity 5 S/cm) in the following proportions: - 1 part (weight) of powdered mix. - 1.5 parts (weight) deionized water. Mix until the product is completely hydrated with a thorough manual action or using an electrical mixer. At the end of the process, seal the container with the cover and leave to hydrate for 8 hours. Before application add a further 1/4 or 1/2 part (weight) of deionized water with respect to the dry powder mass and mix the compound that is now ready for use. (E.g. for the previous pre-mixed compound add a further 0.5 liters of water). Remove all surface deposits with manual brushing with a soft bristled brush. In particular, eliminate salt efflorescence and powder deposits so that the surface is prepared for the extraction of soluble salts. The product action can be improved by spraying with deionized water, waiting around 15 minutes until the water penetrates into the pores of the material before applying the compound. 

Before the application, the surface must be mechanically cleaned beforehand with a brush so as to remove the deposits of crystal salts, also, the surface must not be consolidated before salt extraction. The depth of the reclaimable layer for extraction depends on the chemical/physical features of the material and can be determined via the specific lab analysis of transverse sections of material, taking samples from the surface. DESAL cannot be used on stones previously treated with waterproof sealers because this would block water absorption and salt extraction.