I have had my kitchen ceiling and the walls, which had previously been artexed, professionally plastered. The ceiling is fine but we noticed a series of bumps, about the size of a 5p, on one of the walls. Our plasterer said it was something to do with 'glue' and re-skimmed it after first unsuccessfully trying sandpaper. This part is now OK but after we have applied emulsion to the main walls (after PVA) we've found many other bumps. Could anyone comment on a possible cause and advise action?