Robert:

I'm sure that nowadays the main reason for any ban in to prevent annoyance
and - not least - temporary dazzle (especially in the galleries which for
conservation reasons have very low levels of artificial lighting - the very
spaces where visiting photographers are most likely to want to use flash).

However, photographic oldies amongst us well remember the original reason!

In pre electronic flash days (enormously expensive) one-shot flashbulbs
had to be used.  Despite a protective varnish coating - which used to melt
and almost catch fire very spectacularly when the bulb was fired - perhaps
one in 20 would actually explode. Even with the glass screen in front of
the holders for  smaller bulbs, bits of hot glass could scatter widely,
not exactly the sort of thing you want to happen 5ft from your prize
Poussin!  Even worse, the sort of smaller bulbs that could be fitted
behind the glass screen were usually not powerful enough for anything more
than a head and shoulders portrait, so there was a big temptation to put
in ever larger flash bulbs - up to 5 or 6 inches long with no shatter
screening!

Having seen the effects of a 250 watt flash bulb (one of about
six being fired off simultaneously) shattering while taking a large and
spectacular bone cave interior, some of us went back to exploding finely
ground magnesium "flash powder" (as in those newsmen shots in silent
movies) - feeling that providing you didn't blow yourself up this was a
lot cleaner than a flashbulb that was quite likely to scatter
hundreds of slivers of thin glass where future cavers or excavators might
be crawling about.


Patrick Boylan

=========================

> At 14:49 14.01.98 -0500, Robert Baron wrote:

> >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?
>