I forgot to apply patination oil to new lead flashing around a chimney on a new roof approx 6 weeks ago. The lead has begun to oxidize and so I cannot now apply the oil until I clean / de-oxidize the surface of the lead. If all else fails I will just scrub the lead with a hard brush and attempt to coat the resulting surface though I suspect this is not the ideal solution. It may be too late at this stage but anyone got any suggestions ??