Types of glass compared
The nine glass types you will actually be quoted in India — annealed to mirror — compared on strength, how they break, what they are used for, relative cost and common thicknesses. Use the table to shortlist, then read the notes and decision rules below it.
Comparison table
| Type | What it is | Strength vs float | How it breaks | Typical uses | Price band | Typical thicknesses |
|---|---|---|---|---|---|---|
| Annealed (float) | Standard glass off the float line, cooled slowly with no further treatment | Baseline (1×) | Large, sharp shards — unsafe near people | Small fixed windows, photo frames, cabinet shutters | LOW | 2–12 mm |
| Toughened (tempered) | Float glass heat-treated to lock in compressive surface stress | 4–5× float | Shatters into small, relatively blunt cubes | Shower doors, partitions, table tops, doors, shopfronts | MID | 4–19 mm (5–12 mm common) |
| Laminated | Two panes bonded with a PVB or EVA plastic interlayer | Similar to float per pane; interlayer adds post-breakage strength | Cracks but shards stay stuck to the interlayer; panel stays in the frame | Skylights, overhead glazing, security glazing, sound control | HIGH | 6.38–13.52 mm (3+3 to 6+6) |
| Toughened-laminated | Laminated glass built from toughened panes | 4–5× float, plus post-breakage retention | Breaks into cubes that stay held by the interlayer | Frameless railings, glass floors, canopies, high-security glazing | PREMIUM | 11.52–17.52 mm (5+5 to 8+8) |
| DGU (double glazing) | Two panes factory-sealed around an air or argon gap | Depends on the panes used (annealed, toughened or laminated) | Each pane breaks like its own type; the unit loses its seal | Exterior windows and doors, AC heat-gain and noise reduction | HIGH | 18–32 mm overall (e.g. 6-12-6) |
| Frosted / etched | Float or toughened glass with one face acid-etched or sandblasted for translucency | Same as the base glass | Same as the base glass | Bathroom windows, office partitions, doors needing privacy with light | MID | 4–12 mm |
| Tinted / reflective | Body-tinted or metallic-coated glass that cuts glare and solar heat | Same as the base glass (heat-strengthening advised for high solar load) | Same as the base glass | Facades, west-facing windows, hot-climate glazing | MID | 4–12 mm |
| Lacquered (back-painted) | Float glass with an opaque coloured coating baked onto the back face | Same as float (toughened versions available) | Same as the base glass | Kitchen backsplashes, wall cladding, wardrobe shutters, writing boards | MID | 4–6 mm |
| Mirror | Float glass with a silver coating and protective backing paint | Same as float | Large sharp shards (safety-backed and laminated mirrors available) | Vanity and wardrobe mirrors, gym walls, decorative panels | LOW | 3–6 mm |
Price bands are relative labels, not quotes — actual rates depend on thickness, city, quantity and fabricator. For indicative ₹ per sq ft ranges, see the glass price guide.
Each type in brief
Annealed (float) glass
The default, untreated glass that everything else is made from — in India most of it comes off Saint-Gobain, AIS, Gold Plus or Modi Guard float lines. It is the cheapest option and cuts easily on site, but it breaks into long sharp shards, so keep it away from doors, low-level glazing and anywhere people can walk into it. It arrives in standard sheet sizes that fabricators cut down.
Toughened (tempered) glass
Annealed glass reheated to about 620°C and quenched, making it 4–5 times stronger and turning its breakage into small blunt cubes. It is the workhorse safety glass for shower doors, partitions, table tops and shopfronts, but it cannot be cut or drilled after toughening. Pick the thickness from the application using our glass thickness guide.
Laminated glass
Two panes bonded under heat and pressure with a PVB or EVA interlayer, so a broken panel cracks but stays in one piece in its frame. That post-breakage behaviour is why codes push laminated glass for skylights, overhead glazing and fall-protection — see Indian glass standards (IS 2553) for where it is mandated. The interlayer also damps sound noticeably.
Toughened-laminated glass
Laminated glass built from toughened panes — the strength of toughening plus the stay-in-place behaviour of lamination. It is the standard choice for frameless railings, glass floors and canopies. Panels get heavy quickly at these thicknesses, so check handling and hardware ratings with the glass weight calculator.
DGU (double-glazed unit)
Two panes factory-sealed around a dry air or argon gap, cutting heat transfer and noise compared with single glazing. Either pane can itself be toughened, laminated or Low-E coated, which is how facade specs are built up. Costs vary widely with the makeup — the glass price guide has indicative ₹ ranges.
Frosted / etched glass
Ordinary or toughened glass given a translucent matte face by acid etching or sandblasting, so it passes light but blocks the view. It is the standard answer for bathroom windows, office cabins and partition privacy bands. The treatment does not change strength, so the safety rules of the base glass still apply.
Tinted / reflective glass
Glass coloured in the melt (tinted) or coated with a metallic layer (reflective) to cut glare and solar heat gain — common in grey, green, blue and bronze on Indian facades. Because a dark pane absorbs heat, fabricators often recommend heat-strengthening or toughening for large sun-facing panels. Coating and solar jargon is decoded in the glass glossary.
Lacquered (back-painted) glass
Float glass with an opaque coloured coating baked onto its back face, giving a glossy, seamless coloured surface that is easy to wipe down. It is the usual pick for kitchen backsplashes, wall cladding and wardrobe shutters. Compare its cost against tiles and laminates using the glass price guide.
Mirror
Float glass silvered on the back and sealed with protective paint; better grades add a copper-free, moisture-resistant backing for bathrooms. Standard mirror breaks like annealed glass, so for gyms, wardrobes and full-height panels ask for safety-backed (vinyl-backed) or laminated mirror. Common stock thicknesses are 3–6 mm.
How to choose — quick rules
- Glass near people — doors, partitions, table tops, shower enclosures → toughened is the minimum.
- Overhead glazing or fall-protection — skylights, canopies, railings, floors → laminated (toughened-laminated for frameless railings and floors).
- Heat or noise problem — AC rooms, traffic-facing bedrooms → DGU.
- Privacy without losing daylight → frosted/etched (or switchable smart glass if the budget allows).
- West-facing glare and heat on a budget → tinted or reflective.
- Solid colour on a wall or backsplash → lacquered (back-painted).
- Fixed, small, out of reach and cost-critical → plain annealed is acceptable.
Frequently asked questions
Toughened vs laminated glass — which is better?
Neither is universally better. Toughened is stronger against impact and cheaper, so it wins for doors, partitions and table tops. Laminated holds together after breaking, so it wins wherever glass must not fall or be breached — skylights, railings, security glazing. Toughened-laminated combines both properties for railings and floors.
Can toughened glass be cut after toughening?
No. Toughening locks the panel in a state of high internal stress, and any cut, drill or edge grind releases that stress and shatters the whole panel. All cutting, holes and cut-outs must be done on the annealed blank before it enters the furnace, so sizes must be final before ordering.
What is heat-soaking?
Heat-soaking is an optional factory test for toughened glass. Panels are held at around 290°C for a few hours to force any nickel-sulphide inclusions — the main cause of spontaneous breakage — to fail in the oven rather than after installation. Specify it for facades, railings and overhead toughened glass.
What is the difference between float glass and annealed glass?
In everyday use, none — they describe the same product two ways. Float refers to the manufacturing process, where molten glass is formed on a bed of molten tin; annealed refers to the slow, controlled cooling it then receives. Ordinary window glass is float glass in its annealed state.
Is DGU worth it in India?
Usually yes for air-conditioned rooms and noisy or west-facing exposures, where a DGU cuts heat gain and noise noticeably and lowers AC running costs. It is harder to justify for non-AC rooms or shaded elevations. Payback depends on your city, orientation and AC usage, so weigh it case by case.
Which glass should I use for a staircase railing?
Use 12 mm toughened glass as the minimum for framed or clamped railings. For frameless designs, or anywhere a falling panel could injure someone, use toughened-laminated glass (typically 6+6 mm or 8+8 mm with a PVB or ionoplast interlayer) because it stays in place even after breakage.
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