Strange patches

[Joj0B]

Hi,
I'm new here so please be kind!

I'm in the process of 'doing up' my first flat with the help of my Dad. We've recently finished the living room...or so I thought!
After removing the horrible raised wallpaper, we discovered an odd looking patch halfway up the party wall, in the corner. It was about two foot long and looked like glue as it was quite shiny, we thought it was old wallpaper paste. We washed the walls down (after filling the cracks and sanding) and then applied diluted pva. The patch was still present, we papered with heavy duty lining paper and have painted 2/3 coats of my chosen colour on top. This was all completed about 6 weeks ago.

Since then the patch has come back, it is now joined by similar patches all along the wall at roughly the same height. There is one or two near the ground in the same corner and there are two which look spotty. Everytime I go to the flat (about once a week) I notice a new patch/stain. The flat is empty but the room is carpeted with some furniture in there, it does get quite warm in the room as it has patio windows and full sun in the morning.

Does anyone have any ideas as to what it is or how to cure it?
I'll try and get some photos up later.

Any info would be appreciated as I feel really disheartened at the moment!
Thanks,
Jo.

 

[joe-90]

Whenever I've seen this it is an old fashioned damp block. Is it an outside wall? Or a chimney breast wall? Try a modern stain block from B&Q or wherever. If all else fails you'll have to use a thick lining paper.

 

[Thewaltons]

first you need to find why the stains are geting there. we used to just put oilbased undercoat on stains and that used to work well. carl

 

[Joj0B]

I had a damp proof course last year on other parts of the flat, I pointed out the first patch then as it was visible on the plaster once the wallpaper had been stripped. The surveyors said there was no damp in the room and the patch was possibly glue.

The area affected is the adjoining wall to next door, no chimney breast just a plain wall with a radiator in the middle. It looks like the previous owners have tried to do their own damp proofing as the wall is plastered halfway up the wall running the entire length. The patches are predominately above this although there are some near the skirting.

I took some photos on my phone, not sure if they'll come out but will try and post them later.

I think I'll try the oil based undercoat, can I apply it directly on top of the lining paper and paint?

Thanks for the advice so far - Jo.