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Photographic Flash: Threat or Nuisance?

David Saunders
Technical Bulletin Volume 16, 1995


A range of traditional organic pigments was ground in gum arabic and applied to conservation grade paper. Different sets were exposed to filtered gallery lighting at 80 and 200 lux and to multiple exposure to photographic flash units with and without ultraviolet filters, until each set had received the same exposure.  Blue wool standards 1-3 were also exposed.

Colour measurements showed that the modest degree of fading produced was the same for each lighting situation, i.e. the reciprocity rule for exposure to light held in these circumstances.  This indicates that modern flash units are not powerful enough to initiate two-photon degradation processes, as had been suggested in the past.  In view of this, the National Gallery recommendations for photographic lighting now favour flash over continuous lighting because the total exposure during a photographic session is lower with flash photography.


blue wool standard, colourfastness, filters, flash photography, photography, standards, ultraviolet light

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Photographic Flash: Threat or Nuisance?, David Saunders (PDF 1.25MB)

To cite this article we suggest using

Saunders, D. 'Photographic Flash: Threat or Nuisance?'. National Gallery Technical Bulletin Vol 16, pp 66–72.

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