I have a large area of brick upstairs wall (say 2 by 3m) which is visibly damp from the outside. I think the original problem was caused by an overflow pipe, long since rectified (we're talking some years ago). At the time, the internal wall was damp, and I stripped off the lining paper to the plaster, and have left unpainted - the wall there is inside a fitted wardrobe so I have been OK to leave it bare. But although the plaster now never looks or feels damp, the external brickword always looks dark, and gets darker in damp weather. THe brick is a very soft victorian brick.
I have read the advice here in the project pages, and have coated the external wall with a sealant. What I have not done is re-plaster that wall, because as said above, the plaster seems dry and so I assume the damp comes from the outside and is not due to moist air inside. There are no other obvious sources of damp (have checked tiles and pipework, etc).
To me it seems as if the salts in the bricks are drawing in the damp from the external atmosphere. From the above description, does that seem a fair analysis, and is there anything I can do to neutralise those salts?