So I had a ton of steel dust on my car and heard about Iron X and how well it works. I thought I'd give it a try because my paint literally felt like sandpaper.
I ordered the 500 ml bottle and almost used it all! The areas that turn purple contain steel/iron dust:





As you can see, my car was covered in steel dust but this stuff really works well! I'm going to use the little bit I have left on the roof again as its a little gritty feeling (but much improved) but the rest of the car turned out great. It has literally saved my paint.

It is a really hard product to find online as it always seemed to be sold out so I ordered it directly from the manufacturer. $18.99 + $35 shipping (to Canada, ouch!) but totally worth it.

 

Mother's clay bar kit from Crappy Tire works too. I use it every year to remove rail rust spots from my Taffy White.