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Sodium Metasilicate Pentahydrate

  • Bases
  • CAS 10213-79-3
  • IUPAC: Sodium metasilicate pentahydrate

Sodium Metasilicate Pentahydrate (CAS 10213-79-3) appears in 1 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is readily biodegradable.

At ingredient (neat) concentration, CLP/GHS data classifies this hydrate as Eye Dam. 1 (H318), Skin Corr. 1B (H314), Met. Corr. 1, and STOT SE 3 (H335) - Danger. At the 1-<5% concentration disclosed in this product's SDS Section 3, the mixture-level classification (SDS Section 2) does not carry these ingredient-level codes through - the finished product classifies only as Eye Irrit. 2A (H319) and Skin Irrit. 2 (H315), consistent with GHS mixture-classification concentration cutoffs. Not itself Prop 65-listed.

Sodium metasilicate pentahydrate (CAS 10213-79-3) is the pentahydrate form of the inorganic alkaline builder sodium metasilicate, distinct from the anhydrous form (CAS 6834-92-0) tracked separately in this catalog. It functions as a pH booster and grease-cutting alkalinity source in citrus-based all-purpose cleaners and degreasers.

At neat (ingredient) concentration, safety data sheets classify this hydrate as corrosive to skin and causing serious eye damage (H314/H318), plus a respiratory irritation classification (H335) - a genuinely hazardous material at full strength. In finished products where it is disclosed at low single-digit percentages, the mixture-level classification is milder: only eye and skin irritation (H319/H315), not the ingredient's own corrosive/serious-damage tier, consistent with how GHS mixture-classification concentration cutoffs work. This is why a product's Section 2 label can read WARNING even when a Section 3 ingredient is individually classified DANGER - the finished-product concentration matters.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
yes
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
3/5
Purpose: Alkaline builder and grease-cutting alkalinity source in citrus-based degreasers; distinct hydrate form from anhydrous sodium metasilicate (CAS 6834-92-0), with its own SDS hazard classification

Common questions about Sodium Metasilicate Pentahydrate

What is Sodium Metasilicate Pentahydrate used for in car care?
Alkaline builder and grease-cutting alkalinity source in citrus-based degreasers; distinct hydrate form from anhydrous sodium metasilicate (CAS 6834-92-0), with its own SDS hazard classification
Is Sodium Metasilicate Pentahydrate a VOC?
No. Sodium Metasilicate Pentahydrate is not classified as a volatile organic compound (VOC).
Is Sodium Metasilicate Pentahydrate on California's Proposition 65 list?
No. Sodium Metasilicate Pentahydrate is not on California's Proposition 65 list.
Is Sodium Metasilicate Pentahydrate biodegradable?
Yes. Sodium Metasilicate Pentahydrate has a confirmed biodegradable profile.

1 product contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.