Naphtha (Petroleum), Hydrotreated Heavy

Naphtha (petroleum), hydrotreated heavy (CAS 64742-48-9) is a complex combination of hydrocarbons obtained from petroleum refining, with the heavy naphtha fraction further treated with hydrogen to remove sulfur and aromatic impurities. The carbon chain range is predominantly C6–C13, boiling 65–230°C. In low-to-moderate concentrations (1–15%) it functions as a carrier solvent, contributing no mixture-level classifications. When used at 80–100% of a formula (as in the Gyeon Q2 Mohs EVO ceramic coating carrier), it drives the mixture's primary hazard profile: aspiration hazard (H304 — fatal if swallowed and enters airways), skin corrosion (H314 — causes severe skin burns), and serious eye damage (H318 — causes serious eye damage). The severity at high concentration is the same chemistry as petroleum distillates used in concentrated industrial solvents and paint thinners. **VOC profile:** Very high. Pure naphtha VOC is approximately 785 g/L. At 80–100% of a formulation, the VOC contribution is 628–785 g/L — well above any consumer-grade VOC deduction ceiling. **Aquatic toxicity:** Acute fish toxicity LC50 8.2 mg/L (96h Pimephales promelas), algae ErC50 3.1 mg/L (72h), Daphnia NOEC 2.6 mg/L (21d) — classified as a marine pollutant under IMDG. Aquatic toxicity at ingredient level is significant, particularly for acute and chronic invertebrate exposure. **Biodegradability:** Not readily biodegradable per standard OECD 301 criteria for the full hydrotreated heavy naphtha fraction, though lighter fractions do biodegrade over time.