Spots and patches coming through paint

[Deimos]

I’m trying to paint a ceiling and having problems with brown patches and spots coming through in some areas (about 30% of the ceiling). Patches are lighter brown/yellow whereas the spots vary from lighter to dark brown. Spots are limited to a single area which makes me less sure about tar from smoke which in my experience tends to be quite an even coating.

Before starting to paint I washed the ceiling off quite thoroughly and wire brushed it (previous owner smoked but the ceiling was not completely yellow or even noticeably stained). Then on the patches and spots painted a blocking paint (water based). Spots came through, but difficult to say about the patches. Then when well dried painted with a monocouche white acrylic and patches and spots came through quite quickly (using a monocouche I expected I might get away with 3 coats without the stain problem).. The blocking paint I used was water based as the guy in the shop said that oil based ones would make it hard for the subsequent acrylic coats to adhere to properly (no idea if that is true, but it’s what he said).

I do not know if they are cigarette smoke stains as the spots which are very determined to come through are very definite and around 1cm in diam, with a very hard edge.

Do I just carry on until eventually the patches and spots get covered or should I do something else (e.g. paint oil based layer over the problem areas.

I’d appreciate any ideas or suggestions as it’s a difficult ceiling to paint (basically the bits between the large beams so its all by brush with loads of edges to do and avoiding getting paint on the beams.).

Many thanks

Ian

[Dick Smith]

Could there be something above the ceiling which is excreting or otherwise oozing? We have had this from wasps' nests and a large stain which looked like a cow had given birth. We used oil-based blockers and that (eventually) covered it up, but it took a few coats.

[Just Katie]

Also, are the spots confined to one area of the ceiling? Is the ceiling to the first, second or other floor.  It is fine painting it but you really need to know the cause in order to remedy completely.

[Gastines]

Damp patches/Nicotine will bleed through any water based paint.Give it a good coat of OIL based undercoat. I usually go over any patches with a fine roller and that does the trick.You can buy blocking sprays but they are expensive and difficult to use on a ceiling.

Regards.B&B  St.Malo

[Deimos]

[quote user="KatieKopyKat"]Also, are the spots confined to one area of the ceiling? Is the ceiling to the first, second or other floor.  It is fine painting it but you really need to know the cause in order to remedy completely.[/quote]

It’s the ceiling between the ground and 1st floor. Its actually constructed of those hollow bricks laid between very large beams. There is additional stuff above the bricks though I do not know what. However, I do not believe that there is anything coming down from above so sounds like nicotine is the most likely. I will try an oil based undercoat rather than spending loads on special blocking paints (other than the water based one I tried because I happened to have already purchased it for something else).

Many thanks for suggestion.

Ian

[Debra]

You can use ordinary gloss or PVA too

[Bassman]

Unibond usually does a fine job of curing this and normal gloss will also do it [:)]