Efflorescence/Frosting/Mottling: This is a common phenomenon easily recognizable as a white flurry crystalline deposit which forms on the surface of new plaster and cement rendering, or on brick work. This deposit consists of water-soluble salts, originating from within the building fabric, which are brought to the surface by moisture during the process of drying out. Although efflorescence is found mainly on new building work, it is prevalent in many older structures where moisture persists within the walls. Efflorescence can frequently be caused by the penetration of rain water through defective masonry, from leaking water pipes and faulty or unprotected flat roofs and canopies. Rising damp can frequently cause efflorescence particularly in older building which have no effective damp-proof course. Remedy: Where these salts are still forming on the surface it is not advisable to attempt to restrict the process by applying any type of sealer, or impervious oil paint treatment. In these cases an emulsion paint can be applied with reasonable safety as this, being porous, does not restrict the drying out of the moisture, and the salt can crystalise more or less harmlessly on the surface of the paint instead of underneath it. Efflorescence should be removed by dry brushing down from time to time, but on no account should any attempt be made to wash off the crystals as water will only dissolve the salts again so that they are absorbed back into the porous surface. The continued formation of efflorescence indicates that moisture is still present within or gaining access to the building fabric