The new Formula Purple Rain 2.0 is a more advanced product with quicker reaction times to remove the heaviest of Iron Fallout from the surface.
Examples of contaminants - Railway dust, which can be highly resistant to all but the most aggressive detailing clays, and industrial iron-rich fallout.
Purple Rain 2.0 comes to the correct strength for safe exterior use (it is suitable for use on exterior surfaces). Wash and rinse the surfaces you are going to treat in the normal way. Next, spray on liberally, any iron contaminants dissolve into solution, the initially colourless liquid will gradually turn purple/red within approx 1-4 minutes. Thoroughly rinse the surfaces you have treated with a strong stream of water. If you let the solution dry on fully, you may need to use a stronger jet of water from a pressure washer to remove the film.
Tip - You can agitate the product with either a microfibre towel (on bodywork and glass) or a brush on wheels) if needs be. After 5 minutes.