Mould under paint

[Bluevelvetcake2]

hi, we have always had issues with mould on ceilings in the winter even though we keep windows open, have a dehumidifier running and use anti mould paint. I’ve just finished cleaning the ceilings and noticed in one room that there are grey spots that look like mould but don’t clean with the HG spray. Is this mould growing under the paint? Is that possible? I’ve scraped the paint in a few places to see if it will remove black mould underneath but doesn’t seem to be the case so why am I getting these grey dots that look similar to black mould spots and how can I get rid? Thanks!

Mould can grow through paint and into the plaster. It sounds like the plaster is damp - you need to solve that to prevent the mould. E.g. we have a concrete slab on our bay window, it suffers from condensation in the winter and gets damp and mould. I want to replace the whole bay window to solve it!

Do you have water coming in form a leak, or is the ceiling cold and getting condensation?

Thanks. If it was growing into the plaster wouldn’t the surface be black? This is like light grey dots which could almost be mould growing underneath the paint if that’s possible. However the weird thing is that the mould cleaner which works on the actual black mould spots doesn’t work on these light grey ones. When I use a scraper the grey seems to come away though but I’m curious about what this actually is and if there’s another way to get rid off them as in some cases I end up scraping the paint completely off so will need to repaint. I’ve just seen there there is something else called “ghosting” which is grey spots and I wonder if it’s that.

We do have condensation issues and cold ceilings though and I’m planning to get a point in ventilation system installed as I’m really fed up of mould so that will hopefully help.