We have an old stone building. Thick walls, no cavity. Its not been well looked after. I've fixed the worst of the leaks in the roof and windows so now its time to make the interior a little more habitable. I think the walls are lime plaster but they've been patched and skimmed with modern multi finish in places. This is mostly falling off now. Its also been painted over many, many times with any old paint they had lying around as far as I can tell. When you rub your hand on the wall a thick layer of dust and paint comes off. Its had several cleans but its still coming off. Longer term we'll being doing a full renovation but that is a way off. What can be done for now to stop the dust, or is it a case of needing to do a proper job. I know we want it to breath.