Float Process
Definition
The Pilkington 1959 manufacturing method in which molten glass is poured onto a bath of molten tin, producing a ribbon with two optically flat surfaces; now produces the vast majority of the world's flat glass.
- Developer
- Pilkington
- Introduced
- 1959
- Method
- Molten glass poured onto a bath of molten tin
- Result
- Ribbon with two optically flat surfaces
- Market share
- Produces the vast majority of the world's flat glass
Common questions
What manufacturing problem did the float process solve?+
Earlier flat glass methods required grinding and polishing to achieve optical flatness, which was slow and costly. Floating molten glass on tin let gravity and surface tension produce two naturally flat, parallel surfaces without mechanical finishing.
Does float-process origin help distinguish one pane of glass from another in casework?+
Not on its own, since nearly all modern flat glass shares this manufacturing origin. It rules in the fragment as ordinary sheet glass but examiners still rely on physical fit, refractive index, and elemental composition to link a fragment to a specific source.
Related terms
- ASTM E2927
- Standard test method for the determination of trace elements in glass samples using LA-ICP-MS; specifies the element suite, calibration standards (NIST SRM...
- ENFSI ENG3-2013
- The ENFSI Glass Expert Working Group guideline for glass comparison casework; specifies the examination sequence, within-source variation requirements, statistical comparison framework, and...
- Glass-Transition Temperature (Tg)
- The temperature below which a glass behaves as a rigid solid rather than a viscous liquid; a fundamental thermal property that varies...
- LA-ICP-MS
- Laser ablation inductively coupled plasma mass spectrometry; a technique that fires a laser pulse at a sample surface, vaporises a tiny amount,...
- Network Former
- Oxide (SiO2, B2O3, Al2O3) that forms the tetrahedral backbone of a glass network by sharing bridging oxygen atoms between units.
- Network Modifier
- Metal oxide (Na2O, CaO, K2O, PbO, MgO) that introduces cations into the glass network, breaks Si-O-Si bridging bonds, and lowers the melt...
- PVB Interlayer
- Polyvinyl butyral film bonding the two glass layers in a laminated automotive windshield; retains broken glass in place after fracture, preserving the...
- Refractive Index (RI)
- A physical property of glass measuring how much light bends as it passes through. RI is the primary discriminating characteristic used in...
- Tempered Glass
- Glass heat-treated to introduce compressive surface stresses and tensile core stresses, producing a material four to five times stronger than annealed glass...
- Tin-Side Fluorescence
- UV fluorescence (blue-white at 254 nm) of the bottom surface of float glass caused by tin oxide diffused into the glass surface...
- Within-Source Variation
- The natural variation observed among multiple samples collected from a single source location. Used to estimate the probability of the observed difference...