We live in a barn conversion which is newly decorated and have had damp checks carried out which are ok. In one area on the kitchen wall we have darkish shadows coming through the paint which we are told may be due to salts. is there any process or materials we can apply before repainting to stop these coming through?
Logically if the wall is dry salts will not travel to the wall surface so I would suspect damp. You may need to strip back the existing paint and use a permeable paint so the wall can breath.
Yes I would agree - of the stain is changing then it would indicate damp - through the floor or maybe a window frame. First, you need to stop the damp then you need to remove this damaged plater and replace it. Have you had a dmap specialist come out to assess the stains?