FC-13.7-M
Underbody Cleaner / Salt Remover
Ingredients
| Ingredient | % w/w | Function |
|---|---|---|
| Deionized water | qs to 100.0 | Diluent |
| Sodium carbonate | 5.0 | Alkaline builder, salt neutralization |
| Sodium metasilicate | 4.0 | Buffer, corrosion inhibitor |
| APG (, 50%) | 4.0 | Surfactant, mildness |
| Nonionic surfactant (AE, , 7 EO) | 2.0 | Degreasing |
| Citric acid | 3.0 | Salt neutralizer (chloride displacement) |
| Tannic acid | 1.0 | Rust converter (ferric tannate formation) |
| Phosphoric acid (75%) | 1.5 | Rust passivation |
| Corrosion inhibitor (zinc phosphate) | 0.5 | Protective coating |
| Xanthan gum | 0.3 | Thickener, cling to vertical surfaces |
| Total | 100.0 |
Formulation Notes
High-alkaline formulation for road salt, mud, and grime removal from chassis and underbody surfaces with post-clean corrosion protection.
Method: Dissolve sodium carbonate and sodium metasilicate in water. Add surfactants. Add citric acid (reacts with excess carbonate to form sodium citrate buffer). Add phosphoric acid and tannic acid. Add zinc phosphate corrosion inhibitor. Thicken with xanthan gum. Properties: pH 10.0–11.0. This formulation addresses the three requirements of underbody cleaning: (1) alkaline surfactants lift grease and soil; (2) citric acid neutralizes residual chloride salts from road de-icing; and (3) tannic acid converts surface rust (Fe₂O₃) into stable blue-black ferric tannate . The zinc phosphate inhibitor leaves a conversion coating on bare metal that retards flash rusting for 48–72 hours post-cleaning.