Tin-Side Fluorescence
Definition
UV fluorescence (blue-white at 254 nm) of the bottom surface of float glass caused by tin oxide diffused into the glass surface from the tin bath; used forensically to determine pane orientation.
- Cause
- Tin oxide diffused into glass from the float bath
- Appearance
- Blue-white fluorescence under 254 nm UV
- Located on
- The bottom surface of float glass
- Forensic use
- Determining which face of a pane faced outward
Common questions
Why does knowing pane orientation matter in a forensic examination?+
Establishing which side of a broken pane faced the interior versus exterior helps reconstruct the direction of a break, such as which side an intruder struck from, and helps correctly interpret associated fracture and fragment evidence.
Does every type of glass show tin-side fluorescence?+
No, only float glass, which is the dominant modern manufacturing process, shows this effect because it is a direct byproduct of floating molten glass on a bath of liquid tin. Older or specialty glass made by other processes will not fluoresce this way.
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...
- Float Process
- The Pilkington 1959 manufacturing method in which molten glass is poured onto a bath of molten tin, producing a ribbon with two...
- 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...
- 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...