I think I have seen this stuff at work when our plant emitted a lot of metal chips into the air and it settled on all of the cars in the parking lot and it was raining on top of it. All the paint jobs rusted up, chrome and everything over night it seems. They say some filters were blown and had big holes in them so everything was being shot out the roof. The wind had been blowing 30 mph or so for a day or two toward the parking lot so what had settled on the roof and what was being blown out the stack hit the cars. I work for a automotive company, Bosch then, and we make rotors, corner modules, hub and so on so we have a lot of metal chips from the machining processes.
Now you can see where our sidewalks and roofs have turned orange from the dust and chips settling over time and the company vehicles that are parked by the buildings were really etched even the glass.
I happen to of drove my Z06 vette to work the day the wind storms hit and when I got to it after work puddles of rust had settled into the paint. I took my car to a detail shop as well as a few other people about 5 days later and they used a clay bar and removed everything and detailed it at a cost of 428.00.
The other people were waiting on the company to own up and fix the paint jobs. They were looking pretty bad a month later or so. The company finally owned up and contracted a company to evaluated and clean all the cars that had contamination. We are talking 3 shifts and about 500 employees.
This company came in and used clay bars as well but squirted a yellow liquid on the paint first. They did not have to work the clay bar like they did at the detail shop to get the metal off so I am thinking this is what they were using for the lubricant for the clay bar. It took all day at the detail shop and they could do a bad vehicle in a hour or 2. The results they had were awesome. I would not of believed it but I saw the cars before and after and what it took to clay bar one without whatever they were using.
Neil