DIY Doctor UK DIY Forums

Hello,

Can anyone advise on what this looks like:

It does not feel damp, but the paint keeps drying out and flaking off.

As the stain does not start at the bottom, at a guess I would say it could be some contamination in or on the plaster surface staining the emulsion paint. Any staining will come through water based paints however many coats you apply. A simple fix could be a coat or two of OIL based undercoat to seal the stain before applying the emulsion finish coat.