Alkalis are substances with a pH above 7 that form the chemical backbone of most active foam products. In car washing, alkaline compounds are responsible for breaking down fats, oils, proteins, and other organic dirt through saponification and emulsification.
Common alkalis in car wash formulations:
- Sodium hydroxide (NaOH) — strong alkali, highly effective degreaser, requires careful formulation to remain paint-safe.
- Potassium hydroxide (KOH) — similar strength, often preferred for its superior solubility and softer feel.
- Sodium metasilicate — moderate alkali with added paint protection (acts as a corrosion inhibitor).
- Sodium carbonate — mild alkali used as a pH buffer in lighter formulations.
The choice and concentration of alkalis determine the product’s cleaning aggressiveness. Professional-grade products like Fortis Foam PRO balance strong alkalinity with protective additives to deliver aggressive cleaning without damaging vehicle paint.
In two-step washing, the alkaline step (active foam) is followed by an acidic rinse. This combination — first alkalis for organic dirt, then acids for mineral deposits — delivers the most thorough clean. Read our comparison in alkaline vs acidic foams.