Is the below statement true?  It's my understanding that all light is
damaging and that the damage is cumulative.  Thus, even though the flash of
flash photography is brief, it adds to the cumulative exposure and damage.
Even if the below is true for paintings on canvas or panel, is it true for
works on paper and manuscripts which are much more sensitive to light
damage than many other materials.  Or am I mistaken?  Thanks for
clarification.

>> Does anyone on museum-l have any information on the harmful effects (or
>> lack of harmful effects) of electronic flash photography on paintings,
>> manuscripts and paper works of art?
>>
>
>None whatsoever....
>The worst effect is on the eyes of guards standing near famous
>paintings that are being photographed all day long. That is the main
>reason not to allow the use of flashlights in museums.
>
Beverly Balger
Registrar, Palmer Museum of Art, The Pennsylvania State University