Artifact Lighting Calculator

Stone, metal, and ceramics don't undergo the photochemical fading that afflicts organic pigments and dyes, so there's no meaningful cumulative lux-hour dose to track for them — that's why maxAnnualLuxHours returns -1 (no practical limit) for sensitivity class 3. The 300 lux ceiling still applies because it's a comfortable, glare-free viewing level, not a conservation threshold — it's about human visual comfort, not material protection.

Safe operating lux is your proposed illuminance clamped down to the class maximum — it's what the calculator would recommend instead, not what you actually entered. If your proposed lux is 100 for a high-sensitivity object (max 50), safeLux reports 50, while annualExposureProposed still shows the dose you'd actually accumulate at your original 100 lux entry, so you can see exactly how far over the safe operating level you are.

It divides a published just-noticeable-difference (JND) threshold in lux-hours — 150,000 for high-sensitivity materials, 600,000 for medium, 5,000,000 for low — by your annual exposure at the proposed lux level, giving a rough year count until one detectable color shift under the ISO Blue Wool Standard 1 reference. It's a generalized model across a whole sensitivity class, not calibrated to your specific pigment, dye, or substrate, so treat it as a comparative planning number rather than a guarantee of when fading will become visible.

UV causes photochemical damage disproportionate to its contribution to visible brightness, so a light source can be within safe lux limits and still cause excess damage if its UV content is high. The Canadian Conservation Institute's published guidance sets the recommended ceiling at 75 µW/lm, and the calculator checks uvLevel against that same threshold independently of the lux and dose calculations — uvSafe flags whether you're under that threshold, and uvDamageFactor reports how many times over it you are, giving you two separate levers (visible light dose and UV content) to manage rather than one combined score.