Organic dirt encompasses all carbon-based contamination found on vehicle surfaces. It is the primary target of alkaline active foam products and typically makes up 70–80% of the total dirt load on a passenger car.
Common types of organic dirt:
- Traffic film — a complex mixture of exhaust soot, tyre rubber particles, and road oil that forms a grey-brown layer on all surfaces.
- Insect residue — protein-based deposits that bond tightly to paint, especially on the front bumper, bonnet, and windscreen.
- Tree sap and pollen — sticky, acidic deposits that can etch paint if left untreated.
- Bird droppings — highly acidic (pH 3–4) and can cause permanent paint damage within hours.
- Grease and oil — from road spray, engine leaks, or industrial environments.
How it is removed:
Alkaline chemistry breaks down organic dirt through saponification (converting fats into water-soluble soap) and emulsification (surfactants encapsulating oil droplets). The pH of the active foam determines how aggressively it attacks organic contamination.
Fortis Foam PRO is optimised for heavy organic loads, while Fortis Foam ECO handles standard traffic film with a gentler, more biodegradable formulation.
Organic dirt requires different chemistry than mineral deposits like limescale or road salt — this is why two-step washing delivers the best overall results.