Backlit stone diagnosis
Diagnosis: Shadows, Hotspots and Variation in Backlit Onyx
Diagnose dark bands, visible LEDs, hotspots and colour variation in backlit onyx by separating natural translucency from lighting, support, adhesive, ventilation and installation effects.
Onyx is naturally variable
Calcite onyx contains bands, clouds, fissures and areas of different thickness or mineral density. These features transmit light differently and cannot be made perfectly uniform.
Review each slab both unlit and backlit before cutting.
Lighting geometry creates patterns
LED spacing, distance from stone, diffuser depth, optics and cavity reflectance determine whether points or stripes remain visible. Shallow cavities increase hotspot risk.
Corners, frames and supports can cast shadows even when the central field is even.
Stone, backing and joints
Thickness variation, resin, mesh, adhesive ribs and opaque reinforcement alter transmission. Joints and edge frames should be designed as part of the luminous composition.
Do not remove reinforcement without structural review.
| Visible effect | Possible source |
|---|---|
| Regular bright dots | LEDs too close or diffuser insufficient |
| Dark structural bands | Rails, frames or adhesive ribs |
| Irregular cloudy areas | Natural stone density or moisture |
| Colour shift between panels | Slab variation or LED binning |
| Hot local zone | Driver, ventilation or concentrated source |
| Dark edge | Frame depth or light cut-off |
Build a full-size mock-up
Test actual stone, thickness, support, diffuser, LED model, colour temperature, dimming and ventilation. Photograph at agreed exposure but approve visually in person when possible.
Allow the system to reach operating temperature before judging colour and hotspots.
Maintenance and safety
Provide access to drivers and LED modules without removing valuable stone unnecessarily. Control heat and use components suitable for the location.
Record slab positions, lighting specifications and settings so future replacements remain consistent.
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