I had some mold on the ceiling of my bathroom. I scraped it off with a sponge. The thick black mold has gone, but there are still fainter grey stains all over the ceiling which won't come off, even with bleach. I sprayed on PolyCell mould killer (UK product).
How do I know whether or not that has worked? I was told the area would have to be completely dry for it to work. There is obviously a lot of moisture around there every day when we have a shower.
If I now paint over the ceiling with anti-mold paint, how can I be sure the mold is not festering underneath it? Does anti-mold paint prevent existing mold from growing underneath, as well as preventing any new mold from coming on top?