I discovered some models that I'd left to soak in watery dettol about a couple of years ago. The dettol had evaporated a bit and gone sludgy, and there were some peculiar white blobs on some of the parts. When I scrubbed the blobs off there were some neat holes eaten into the metal, with what I assume was further corrosion in and around them. I scraped out the white/grey powdery stuff in them, and put the through a couple of sonic baths, soaks in fairy power spray, and good old-fashioned toothbrush scrubs.
The holes I'm not so worried about, and the parts have been etched (I guess) fairly matt grey, which I can live with; but there's still patches of white discoloration over the surface of some of them. It won't buzz or scrub off, but when it's scraped with a knife it comes off as a powdery residue, a lot like the stuff scraped out of the holes. Thing is, it's also a lot like the way primer turns powdery and scrapes off (or doesn't) after soaking in stripper, except I didn't prime any of the parts white!
I'm worried that it sounds a bit like lead rot, but IIRC GW got rid of lead by the time this titan went into production, and by the time I got into wargaming. I also had old metal hormagaunt bits in the same sludge, that I think still had some lead in them, and that ended up with a lot of fine pitting, but they don't have the same white patches.
Any clue to what's going on? Should I try to get rid of this white before it eats through my minis, or can it be left in place and painted over? Here's a pic that shows it off to some extent. (Click for a slightly closer look) The gun arm shows a few swiss-cheese-bulletholes from the corrosion, but doesn't have much white left on it. The flat plate has a lot more white discoloration - only a couple of tiny, minor patches of that white in the pic are due to glare.