Glossary
If a number on a specification is not clear, it is usually one of these. Everything below is written for buyers and formulators rather than chemists.
SiO₂:Na₂O ratio
The weight ratio of silica to soda in a sodium silicate. It is the single most important number on a silicate spec. Higher ratios (3.2–3.3) carry more silica, set harder and suit adhesives, coatings and silica gel. Lower ratios (2.0–2.4) carry more soda, stay soluble longer and deliver the alkalinity that detergents and foundry binders need.
Baumé (°Bé)
A density scale used for liquids. For sodium silicate it is shorthand for how concentrated the liquor is. Our neutral grades run 37–40 °Bé and alkaline grades 48–52 °Bé. Two liquors at the same ratio but different Baumé carry different amounts of solids per litre, which changes your dosing.
Water glass
The common name for sodium silicate in solution. Same material, older term. Still widely used in trade enquiries.
Total solids
The percentage of the liquor that is actual silicate rather than water. Determines how much active material you are buying per tonne, and matters for freight economics on long hauls.
Sodium metasilicate
A distinct crystalline compound (Na₂SiO₂) with a 1:1 ratio, sold as penta- or nonahydrate. More alkaline and more aggressive than ordinary silicate liquor, used in institutional cleaning and degreasing. Not interchangeable with liquid silicate.
Available chlorine
The measure of oxidising power in sodium hypochlorite, expressed as a percentage. Industrial supply is typically 10–14%. It falls with time, heat and light, so the figure on the CoA is the figure at dispatch, not indefinitely.
Free alkali
Excess sodium hydroxide deliberately left in hypochlorite solution, usually 0.5–1.0%. It is what slows the decay of available chlorine. A hypochlorite with no free alkali will lose strength quickly.
Dense vs light soda ash
Chemically identical sodium carbonate; the difference is bulk density and particle size. Dense (1000–1200 kg/m³) flows and meters cleanly and suits glass batch houses and automated dosing. Light (500–600 kg/m³) dissolves faster and blends better into powders.
Caustic soda lye
Sodium hydroxide supplied as a solution, usually 47–49%, rather than as solid flakes. Removes the dissolving step and the heat and dust that come with it, but requires bunded tank storage and corrosion-rated lines.
Mercerising
A textile process in which cotton is treated with strong cold caustic soda, permanently swelling the fibre. Raises lustre, tensile strength and dye uptake.
CO₂ process
A foundry method in which sodium silicate mixed through sand is hardened by passing carbon dioxide gas through it, forming a silica gel that sets in seconds. Needs no heat or baking oven.
Deflocculant
An additive that keeps fine particles dispersed rather than clumping. Sodium silicate acts as a deflocculant in ceramic slips and drilling muds, letting you carry more solids at a workable viscosity.
Builder (detergent)
A component that improves surfactant efficiency by dealing with water hardness, supplying alkalinity and keeping soil suspended. Sodium silicate and soda ash are both builders.
Saponification
The reaction of an alkali, usually caustic soda, with a fat or oil to produce soap.
Certificate of analysis (CoA)
The document recording the tested values for a specific batch — ratio, density, assay and relevant impurities. Issued with every consignment we dispatch. Always check the CoA against your spec rather than assuming a grade name is enough.
HSN code
Harmonised System of Nomenclature code, used for GST classification and customs in India. Sodium silicate is 28391900, soda ash 28362010, caustic soda 28151100 (solid) or 28151200 (aqueous), sodium hypochlorite 28289011.
CAS number
A unique identifier assigned to a chemical substance. Sodium silicate 1344-09-8, sodium carbonate 497-19-8, sodium hydroxide 1310-73-2, sodium hypochlorite 7681-52-9.