I wonder if anyone can advise me on what to do, to explain..... there were awful cork tiles on bathroom wall, when these were removed there was a browny adhesive (i'm told) left behind - plasterer pva'd and skimmed over - he had trouble with areas bubbling up and I think he will have to reskim as the finish is uneven, however the main problem is that after 2 mists and three normal coats of emulsion there are yellowy brown stains showing through, I've read some post that recommend "shellac-based white-pigmented primer-sealer stain-killer" Zinsser BIN but can the wall then be reskimmed and then emulsioned - any help appreciated. Thanks