I want to give my garage a clear out and a new lease of life, the floor has been painted by previous owner and obviously quite some time ago, in garage floor paint. It is a concrete floor. I thought I would first loosen any of the flaking paint and there are parts where this paint has come off. On brushing I notice the white greyish patches where the paint has come off are just causing continuous dust. I mean I could brush forever and still remove dust, its not a dirty dust but seems almost white and floury. Will this just need PVAing before I repaint in order to seal, or is this something more sinister. Once again your help on this site would be much appreciated. thanks.