Classification | Suitability for exposition | Exposure limits | ||
---|---|---|---|---|
% of total exhibition time | exposure time in a decade | exposure in lux hours per year | ||
BW1 | Very sensitive; not recommended for exhibition | 0% | – | – |
BW2 | Sensitive; not recommended for permanent exhibition at 50 lx | 20% | 2 years of 10 years | 30,000 lx h/a |
BW3 | ||||
BW4 | Less sensitive; suitable for permanent exhibition at 50 lx | 100% | 10 years of 10 years | 150,000 lx h/a |