Sodium Metasilicate

Sodium metasilicate is an inorganic alkaline builder commonly used in heavy-duty all-purpose cleaners and degreasers. It supplies hydroxide ions when dissolved in water, raising pH to 12–13 in the concentrate and providing the saponification chemistry that lifts greasy soils. **Why it matters in detailing APCs**: Sodium metasilicate is the most common alkaline base in professional-line APCs (Meguiar's D101, Mothers Pro, Adam's standard APC). The "DANGER — causes burns" warning on the concentrate label typically traces to this ingredient. At working dilutions of 10:1 or weaker, the working solution is in the moderate-alkaline range (pH ~11–11.5) with significantly reduced skin/eye corrosion potential — the buyer never contacts the concentrate strength during normal use. **SDS alert**: Check Section 3 for CAS 6834-92-0. When present at 1–5% in concentrate APCs, expect signal word DANGER on the concentrate label with H314 and H318. Working-solution chemistry should be evaluated separately per the concentrate-handling rule. ## Regulatory status - Not CA Prop 65 listed - Listed on TSCA inventory; no specific use restrictions for consumer detailing APCs in the US - EU CLP classification: H290 (corrosive to metals), H314 (skin corrosion Cat 1B), H318 (serious eye damage)