The stains are the shape and size of a tennins ball, on the internal surface of one wall in a downstairs room. They appear in a regular pattern every 6 inches horizontally and vertically all over the wall. Beyond this wall is a cavity and then an external wall. The house was built in the 60s, originally had a fire place in the room but no longer. There is no damp in the room.
We put sealer - cannot remember exact make - on the wall before painting it eight years ago. Possibly, the decorator also skimmed it with filler. The wall was fine for 6 years but 2 years ago the stains came back. I am wondering whether to use a sealant such as Lithofin Stainstop this time before painting or perhaps removing the plaster all together and replastering. Grateful for any advice.
We put sealer - cannot remember exact make - on the wall before painting it eight years ago. Possibly, the decorator also skimmed it with filler. The wall was fine for 6 years but 2 years ago the stains came back. I am wondering whether to use a sealant such as Lithofin Stainstop this time before painting or perhaps removing the plaster all together and replastering. Grateful for any advice.