Water glass

Jump to navigation Jump to search


An aqueous solution of Sodium silicate that dries to a hard glasslike mass. Sodium silicate is prepared by fusing silicon dioxide (SiO2) and Sodium oxide (Na2O) in a ratio that varies from 2 to 3.5. A water glass solution is viscous and has little tack, so when it is used as an adhesive, pressure must be applied to hold materials together while bonding. The dried product is brittle and water sensitive. Aluminum salts can be added to the formulation to improve water resistance. Water glass has been used to make artificial stone. Most commonly, it is used as a air-setting cement for bonding paper, corrugated boxes and cartons, wood, glass, porcelain, leather and textiles. Water glass is also used to fireproof textiles and wood. It was tried unsuccessfully as a binder in the 19th century for fresco paintings. Calcium water glass was used in the Ransome process of stone preservation. This procedure used alternating solutions of an alkaline silicate and Calcium chloride to form insoluble Calcium silicate (calcium water glass) in the pores of the stone. Potash water glass is composed of Potassium silicate. Double water glass is a mixture of equal parts potassium silicate and sodium silicate.

Synonyms and Related Terms

soluble glass; soluble silicate; liquid glass; aqueous sodium silicate; flint liquor; silicate of soda; waterglass; water-glass; calcium water glass; double water glass; potash water glass; Ransome process; silicate de sodium (Fr.); vidro solúvel (Port.)


  • Silica gel packets or beads for moisture control
  • Passive fire control
  • Stone consolidation


  • Noncombustible. May dissolve glass.
  • Corrosive. Skin contact causes irritation and burns. Ingestion causes vomiting.
  • PQ Corporation: SDS

Physical and Chemical Properties

  • Soluble in water forming strongly alkaline solutions (pH = 11-12.5)
  • Partially miscible with primary alcohols and ketones.
Composition 2Na2O - SiO2
CAS 1344-09-8
Density 1.3-1.5 liquid; 2.40-2.61 (solid)
Boiling Point 102 C (liquid)
Melting Point 1088 C (solid)

Resources and Citations

  • J.H.Wills, "Inorganic Adhesives and Cements" in Handbook of Adhesives, I.Skeist (ed.), Van Nostrand Reinhold, New York, 1977. p.117-138.
  • R. J. Gettens, G.L. Stout, Painting Materials, A Short Encyclopaedia, Dover Publications, New York, 1966
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 738
  • Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979
  • Dictionary of Building Preservation, Ward Bucher, ed., John Wiley & Sons, Inc., New York City, 1996
  • Kurt Wehlte, The Materials and Techniques of Painting, Van Nostrand Reinhold Co., New York, 1975