Soda-Lime Glass
Soda-lime is the glass of windows, bottles and float sheet: about 72 % silica with 14 % soda and 9 % lime plus a little magnesia and alumina. It melts cheaply, floats into flat sheet from 2 to 25 mm in panels up to 3.2 × 6 m, and is the material for anything that has to be big, flat and clear at the lowest cost. The trade-offs are a 9 ppm/K expansion (poor thermal shock — about a 60 °C step across a 6 mm pane), a service limit near 250 °C, and a green edge tint from iron unless a low-iron melt is specified.
Popular soda-lime glass grades
Compare in the explorer| Grade | Yield, MPa | Tensile, MPa | Density, g/cm³ | Machinability | Weldability | Best for |
|---|---|---|---|---|---|---|
| Soda-Lime | 40 | 40 | 2.5 | Not recommended | Not recommended | Float sheet: panels, covers, mirrors, shelves |
| Soda-Lime Glass | — | 45 | 2.5 | Poor | — | Containers, tubing and drawn forms |
All 2 soda-lime glass grades
Choose soda-lime glass for
Large flat panels — windows, doors, partitions, shelves, mirrors, display and touch-panel cover glass, solar cover sheets — machine guards and inspection covers, cover plates and enclosures, microscope slides, and bottles and containers; anything where cost and sheet size beat thermal or chemical performance.
Look elsewhere when
The part is heated above about 250 °C or heated unevenly (Borofloat 33 or Fused Silica), it holds strong acids or is cleaned with hot alkali for years (Borofloat 33 or Duran), it is a thin device cover that must survive drops (Gorilla Glass), it needs to be scratch-proof (Sapphire), optical index and homogeneity are specified (N-BK7), or the part must be machined after strengthening — tempered soda-lime cannot be cut or drilled.
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Soda-lime glass by application
- Panels, shelves and guards
- Soda-Lime float sheet, tempered for anything a person can lean on or a tool can hit; 4–6 mm covers most enclosures, 8–12 mm for shelves and doors, laminated where fragments must stay together.
- Display and touch covers
- Chemically strengthened Soda-Lime for cost-sensitive panels above about 2 mm and tempered sheet for kiosks and appliances; move to Gorilla Glass when the cover is under 1 mm or drops are the failure mode.
- Mirrors and cosmetic glass
- Low-iron Soda-Lime for edge-lit, thick or back-painted parts where the green tint shows; standard float for silvered mirrors and painted backsheets.
- Containers and slides
- Soda-Lime Glass in pressed, blown and drawn forms — bottles, vials, microscope slides, cover plates — where borosilicate would be overkill and the contents are neutral.
Working with soda-lime glass
- Melting & forming
- Sheet is float-formed on molten tin at about 1,050 °C, annealed and cut to size; the tin side and air side differ slightly, which matters for coatings and mirrors. Bending and slumping run at 600–650 °C, tempering quenches from about 620 °C with air jets, and containers are pressed or blown at 1,000–1,100 °C.
- Cutting & grinding
- Score-and-break for straight cuts, CNC waterjet or diamond routing for shapes, diamond core drills for holes (hole diameter at least the glass thickness, edge distance at least twice it). Edges are seamed, flat-ground or polished on diamond belts and wheels; typical cut tolerance ±0.5 mm, CNC-ground ±0.2 mm. All of it happens before tempering, never after.
- Joining & sealing
- Silicone and structural glazing sealants, UV-curing acrylic adhesives for glass-to-glass and glass-to-metal furniture joints, PVB or EVA lamination between sheets, and frit-sealed or gasketed frames. No glass-to-metal fusion seals — the 9 ppm/K expansion matches few alloys — and no rigid bolting; clamp through resilient bushings and gaskets.
- Tolerances & design rules
- Design annealed soda-lime for about 7 MPa long-term tensile stress and tempered for 25–35 MPa; support the pane on its edges on compliant setting blocks and keep any thermal gradient across a pane below about 40 °C. Radius corners (3 mm or more), keep holes and notches away from edges, and specify edge finish — a seamed edge roughly doubles the strength of the same pane.
Other glass series
Soda-Lime Glass — frequently asked
What is soda-lime glass?
Soda-lime is the glass of windows, bottles and float sheet: about 72 % silica with 14 % soda and 9 % lime plus a little magnesia and alumina. It melts cheaply, floats into flat sheet from 2 to 25 mm in panels up to 3.2 × 6 m, and is the material for anything that has to be big, flat and clear at the lowest cost. The trade-offs are a 9 ppm/K expansion (poor thermal shock — about a 60 °C step across a 6 mm pane), a service limit near 250 °C, and a green edge tint from iron unless a low-iron melt is specified.
Which grade of soda-lime glass should I use?
Soda-Lime float sheet, annealed, for covers, shelves, mirrors, backsheets and machine guards where the pane is supported on its edges and stays near room temperature. Specify the same glass thermally tempered when impact, wind or a thermal gradient is the load — full tempering gives four to five times the annealed strength and dices into small fragments on failure, but every cut, hole and edge must be finished before tempering. Specify heat-strengthened for twice the strength without the dicing fracture, and low-iron ("extra clear") when colour matters on thick or edge-lit parts. The generic Soda-Lime Glass entry covers container, tube and drawn forms of the same composition.
Which grade of soda-lime glass is easiest to machine?
Soda-Lime Glass (machinability poor, 20/100), then Soda-Lime (12/100).
Tempered or heat-strengthened soda-lime?
Fully tempered glass carries a surface compression of 69 MPa or more, is four to five times as strong as annealed sheet, and shatters into small blunt fragments — the safety-glass behaviour required for doors, guards and anything a person can fall against. Heat-strengthened glass carries 24–52 MPa, is about twice as strong, and breaks into large pieces that stay in the frame, which is preferred for laminated panels, spandrels and overhead glazing. Both must be cut, drilled and edged before the heat treatment; tempered glass also shows faint stress patterns under polarized light and can spontaneously fail from nickel-sulfide inclusions, so heat-soak testing is specified where that risk matters.
How much heat can soda-lime take?
Continuous service is limited to about 250 °C before it starts to relax and lose any temper; softening begins near 720 °C. The real limit is thermal shock — with a 9 ppm/K expansion a 6 mm pane cracks at a temperature difference of roughly 60 °C across its surface, and thicker glass tolerates less. Tempering raises the tolerable step to 200–250 °C, which is why oven doors use tempered soda-lime; above that, or for uneven heating such as a flame or hot spot, switch to Borofloat 33 (3.3 ppm/K, 450 °C) or Robax glass-ceramic.