brown speckles stains coming through lining paper

[chocdrop]

Hi

Just decorating my sisters toilet. I've taken off the old wall paper and prepped the walls by filling holes and rubbing down the walls. I put on the lining paper a few days ago, and went back today to carry on. I've found a small wavy line of brown speckles on the paper beneath the window sill. Not sure what this is, but is there anything like a stain block that I can paint over it before applying my final matt coloured coat. Everything in B&Q has to be put onto bare plaster first and then wallpaper.

I'm a little concerned that once the top coat has gone on, the speckles might come through that too.

 

[Zampa]

They could be rust stains from something on/in the wall activated by the paste...give em a dab of oil based undercoat., that normally seals most stains.

 

[chocdrop]

cheers Zampa. I thought something had reacted with the paste too. I'll give that a go