Rondekloof Collection Galleries

The conservation team arrived with a number nobody wanted to hear: 50 lux on the textile rooms. Most designers treat that as a ceiling and stop there. We treated it as a budget instead, working in lux-hours per year, which let us run the galleries at 50 lux during opening hours and take them to near zero the rest of the time. Presence detection in the two most sensitive rooms adds a further reduction, and the annual dose now sits around 90,000 lux-hours against a 150,000 limit.

Spectrum mattered more than the number. Early samples of a 2700K LED had a heavy spike below 450 nanometres that made indigo-dyed cloth look purple and pushed the relative damage factor higher than the illuminance suggested. We tested four sources against the actual objects in the store, measured spectral power distribution on each, and specified a filtered 3000K package at CRI 95 with R9 above 90 and no measurable output below 400 nanometres. The curators saw the difference on a single sample before the meeting ended.

Delivery was track and framing projectors on a 1.2 metre grid, because the hanging plan changes twice a year and a fixed scheme would have been obsolete by the first rotation. Every fitting is on a wireless DALI node so a curator can re-scene a room from a tablet without calling a contractor. We ran the focus over eleven nights with the exhibition designer present, and left an aiming report that records beam angle, barn-door position and dim level for all 340 fittings.