SiO2–Na2O–CaO (typical soda-lime)
ChemistryGlass is specified as SiO2–Na2O–CaO (typical soda-lime). Density band ~2.5 g/cm³.
Darker cells mean a higher score for this topic on that metric.
Strength50
Heat resistance58
Fire performance88
Insulation28
Workability55
Circularity70
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Last reviewed Sources & creditsMedia creditsMethodology
Quick answers
Is Glass non-combustible?
Declared reaction class in this atlas: A1. Assemblies still need resistance tests.
Does Glass insulate?
Thermal mark 28/100 versus the atlas. Conductivity note: ~1 W/m·K.
What is the density band?
~2.5 g/cm³
How is it made?
Origin story: Mesopotamia / Egypt; float 1959 (Near East → St Helens).
Can it be recycled?
Circularity mark 70/100 — editorial, route-specific.
Typical melting or failure heat?
softens ~500–700 °C
heat 58 · fire 88
What holds Glass together is not the nickname. Formula SiO2–Na2O–CaO (typical soda-lime), density ~2.5 g/cm³.
Meters are atlas-relative. Grades are the SKUs buyers write.
Phases
Microstructure
OrderProcessing sets grain, crystallinity or fibre orientation — the reason two lots of Glass can test differently.
Interfaces
SurfacesCoatings, oxide films, sizings or paper faces often decide weather and fire behaviour more than the bulk brochure.
Defects
FlawsInclusions, voids, knots, pinholes or residual stress start the failures that mill certificates do not list.
Grades
VariantsGlass is a family. Grade names below are the ones buyers actually write on RFQs.
Ageing
TimeMoisture, UV, creep, hydrogen or carbonation shift properties in service. Design to the aged state.
Relative meters
Strength50
Strength is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Heat envelope58
Heat envelope is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Fire behaviour88
Fire behaviour is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Insulation28
Insulation is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Workability55
Workability is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Circularity70
Circularity is an editorial 0–100 mark relative to the other 31 materials in this atlas — not a laboratory certificate.
Grades
Soda-lime float
Windows, mirrors.Windows, mirrors.
Tempered
Safety doors.Safety doors.
Laminated PVB
Overhead / hurricane.Overhead / hurricane.
Borosilicate
Lab and cookware.Lab and cookware.
Fire-rated
Integrity / insulation glasses.Integrity / insulation glasses.
Bonds
Primary bonding
Glass holds together by ionic/covalent networks.
Secondary forces
Hydrogen bonds, van der Waals stacks or grain-boundary cohesion set toughness and moisture uptake.
Composites & fills
Fillers, fibres, plasticisers or aggregates are part of the real product, not impurities.
Environment film
Oxides, chars, sizings or paints are the layer the world actually meets.
Change the grade, the coating or the moisture and you have a different material with the same English name.
Keep exploring
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