Museum lighting strategies for sculptural non-photosensitive exhibits: the role of bottom illumination and optimal CCT

Lighting design is a key component of indoor museum environments, influencing both object visibility and viewers’ visual experience. However, existing studies have mainly focused on planar artworks or general interior lighting, while three-dimensional, non-photosensitive ceramic displays remain underexplored. This study examined the effects of illuminance, correlated colour temperature (CCT), and exhibition method on colour preference for Chinese cold-toned glazed porcelains through three psychophysical experiments with 142 adult observers. Experiment 1 investigated the illuminance ratio between top-down and bottom-up lighting in a freestanding display case using an indigo-glazed porcelain vessel. Results showed that bottom lighting significantly enhanced preference by revealing shaded details, with the optimal combination of 2250 l×(top-down) and 1600 l×(bottom-up). Experiment 2 found that preference increased with CCT up to 4000–5000 K and then declined, challenging the conventional preference for lower CCT in museum lighting. Experiment 3 compared a laboratory lighting booth with a real display case and found no significant overall difference, with strong correlation between results (Pearson r = 0.93). A significant illuminance × CCT interaction was also observed. These findings suggest that 4000–5000 K CCT and bottom illumination can improve the visual experience of Chinese cold-toned glazed porcelains in exhibition interiors.