Museum Textile Light Fading & Cumulative Lux-Hour Budget

Reciprocity is assumed — that lux and hours trade freely and only their product matters — which holds well enough over normal display ranges but breaks down at very high illuminance, where damage runs ahead of the dose. The Blue Wool scale is also a coarse ordinal ranking rather than a measurement of a particular object, and a real historic textile carries several dyes of different sensitivity, so the most fugitive one governs and it is rarely the one the eye notices first. Damage from heat, humidity cycling and pollutants accumulates alongside light and is not in this budget. Display decisions for significant objects belong with a qualified conservator, informed by microfading testing where the object justifies it.