cheers lads, its got to be a paint that lets efflorescence salts pass through with no damage, ie you just wipe the wall with a sponge when they appear, iam thinking some sort of mineral emulsion, but tomorrow will dig deeper,.the walls are dry and most of salts seem to have come through the existing plaster, one coat machine sprayed, salts kill it completly, push your fingers in it, this is a bodge job for a mate, he can not afford the right gear to do it properly, s@c and skimmned, idea being if the salts try to come through the s@c and the skim they can pass through the paint to the surface and be wiped off. cheers del