Iron fallout, or ferrous fallout is something that, with modern high traffic volumes, has become a greater issue to detailing. Although often referred to as industrial fallout and very common around train lines, a majority of the iron contamination comes from road user's brake pads; each time the person in front of you brakes, microscopic pieces of iron fly into the air and pelt your cars paint work. Of these particles, a fraction can become embedded in the paint due to the sharp, jagged edges (we're on a tiny scale here), especially if unprotected, and can lead to body corrosion if not addressed. Especially prevalent in the case of alloy wheels, where the iron particles, plus road salt can lead to electrolysis, speeding up under-paint corrosion.
Semi-regular treatment with a fallout remover safely dissolves the sharp edges of these iron particles, loosening them from the paintwork surface without affecting the surrounding area and enabling them to be safely washed away. However using those too often CAN damage surfaces, and is unnecessary as most iron fallout will be removed with simple regular washing, hence why regular waxing as prevention is better than remedy.
The downside is, they smell rotten, largely due to the ammonic reaction with citric acid, thioglycolic acid, and the iron itself, the combination of which results in the purple/red colour change associated with the products.
If your car, or wheels seem clean, but upon closer inspection reveals tiny black dots, sometimes with an orange halo, this is a good indication of iron contamination and something we can help with removal of.