Fitting blueprints in a lighting policy: possibilities for exhibiting architectural drawings

This article describes the lighting policy framework of Het Nieuwe Instituut, the national museum and archive for architecture, design and digital culture in Rotterdam, the Netherlands. The framework combines relative cultural value, light sensitivity and acceptable loss of value due to colour change into recommended annual light doses for objects. To fit the blueprints into the policy, the loss of value upon fading and regain of the blue colour was studied. As other studies have shown, the fading of Prussian blue due to photo-reduction was reversed by the oxidation of the formed Prussian white in the dark. Overall colour changes remained unnoticeable to the naked eye. Although blueprints are highly sensitive to light, the loss of value after exhibition is minimal, therefore display possibilities are wider than thought. Nonetheless, pristine blueprints should be displayed with care when their colour is a character-determining feature. Additionally, some architectural drawings may look like blueprints but have been produced by different techniques and may fall in the ‘high’ light sensitivity class as they can never regain their colour.