The electrical conductivity of wetted stone is affected by the concentration of salts in pore fluids. Higher salt concentrations result in higher conductivity. An electrical conductivity probe can therefore be used to obtain semi-quantitative data on the soluble salt content near the surface of wetted building stone. This can provide information on salt loading and provide a rapid field method for determining the efficacy of the wash-off process following chemical cleaning. Experimental investigations have been made of the conductivity of salt solutions and sandstones soaked in salt solutions. Further experiments examined the conductivity of samples of chemically cleaned and uncleaned sandstones where the soluble salt content has been quantified by depth profiling for soluble salts. Results showed a positive correlation between conductivity and the concentration of soluble salt in the outer 2 mm of the stone. Chemically cleaned sandstones did not always have the highest soluble salt contents or conductivity; stone samples from coastal locations and particularly polluted urban sites could also have high salt loading and consequently high conductivity readings. Readings of conductivity following chemical cleaning of granite building stone suggests that chemical residues are also present on the surface of the granite, despite its low permeability. If the accuracy can be improved, this technique could be used to obtain semi-quantitative data on salt loading near the surface of building stone without the need for destructive analysis (e.g. coring or drilling). This could be usefully applied to rapid assessment of the efficacy of wash-off after chemical cleaning.