Damp mark on ceiling - how to seal before repainting?

waterwatereverywhere

Hi,

We have a very water stained ceiling following a damaged pipe in a loft some while back. The leak is all cured but ceiling has brown staining.

We know of the Polycell stain block stuff you can buy but it's very expensive.

Someone in the DIY shop told us we could just buy some cheap "PVA glue" and mix it with water and paint that on instead.

We've also heard we could just use gloss paint instead.

We'd need to do the whole bathroom ceiling.

Pls can anyone advise whether the PVA or gloss paint options are effective and which might be best?

We will then want to just use ordinary emulsion over the top.

Many thanks in advance for any tips. Can't wait to have a white ceiling again...

phill99

I run a property maintenance company and we com across this a lot. We always use an oil based undercoat ( the type you use on wood). Let in dry then just emulsion over it as normal.

Don't use gloss, as the emulsion struggles to adhere to this and it will peel off.

Leif

I'm not sure Zinsser 123 is much more expensive than a tin of gloss undercoat, and being water based it dries quicker, and is less messy. I suspect it is pretty much the same stuff as water based undercoat i.e. acrylic. And for large areas Zinsser Gardz might work as well, but be cheaper, albeit without any covering power in terms of colour.

PVA is exactly what you don't need. It prevents the paint adhering to the plaster, and it reactivates when damp.