Cheers roger. So, there is nothing out there that will rectify it if its already happened? Have problems when cleaning bricks. The acid stains the lead. Only option ive found is to paint it but never lasts long. Thought there might be something out there to take the acid tarnish off.
Unfortunately it does stain mate, we've all done it at some point, but you could do no worse then get some Net-Rol it's what we use to brighten decking, and is citric based, I don't know what size containers it comes in, (as in smaller sizes) as I buy the 15lt tubs, I think they might do a 1lt size though but not sure. Old stains are hard to shift as the hypo has had time to set/eat the face of the lead. If you are working with loads of lead, maybe mask/cover with polythene or similar ? prior to working.