I've recently bricked up my fireplace & plastered over it. The fire was in use last year burning coal. I've now gota couple of water like patches with a rusty look in one area & the plaster looks darker @ the bottom. I've taken all old lead piping out from behind what used to be an old back boiler & that was drained before using the fire.
What can I do? my house is in the middle of being sold so I need to get something done quickly & with as little expense as poss!! Thanks