Re: what is the best Plexiglas?

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From: Robert W. Schramm (schrammrus@hotmail.com)
Date: 02/23/01-08:21:29 PM Z

The last time I saw the Mona Lisa there were at least 50 japanese tourists in front of it and almost every one had a Nikon with a big flash unit. There were so many flashes going off I thought I was in a disco. And yet there are signs all over the Louvre that say, "Photos au flash interdites." The guards, however, seem to be unconcerned. Mona has something over the front. It could be glass or plastic or both. I saw the guards "remove" someone from the British Museum for using a flash in the rare book area. In Germany, if you even show a camera in a museum the guard will warn you not to use a camera. I once tried, "Nicht blitzen." It didn't work. Maybe I should have added, "Ich haben sie ein Leica." I've never looked into it but I suspect the xenon flash tube does produce some UV but the duration is what? Maybe 1/2000 sec- 1/5000 sec. Still 10,000,000 japanese tourists would produce 30-160 minutes of light allowing one flash per tourist ;-0 I have often wondered if the interdict against photos is so you w

Bob Schramm



 

>From: Judy Seigel
>Reply-To: alt-photo-process-l@sask.usask.ca
>To: alt-photo-process-l@sask.usask.ca
>Subject: Re: what is the best Plexiglas?
>Date: Fri, 23 Feb 2001 16:13:35 -0500 (EST)
>
>
>
>On Fri, 23 Feb 2001, Greg Schmitz wrote:
>
> >
> > A meter reading taken at my studio desk with overhead fluorescent bulbs
> > shows that aprox. 143 lux are striking the surface. Thus, for example,
> > 143 lux * (10 hours * 60 minutes * 60 seconds) = 5148000 lux seconds
> > (15.45 LOG EXPOSURE). That 10 hour exposure would be the same as
> > pointing a light source emitting 5,148,000 lux at your artwork for 1
> > second or an 85,800 lux source for 1 minute or a 14,300 lux source for
> > 1 hour.
>
>
>Greg can you translate into whether that SHOULD or SHOULD NOT have faded
>the painting on the wall? I somehow have misplaced my comparison swatch
>of that painting, but the background was quite delicate pink and yellow,
>which, if ANYTHING look brighter now (really). (Maybe the wall got dirty.)
>
>Judy
>
>
>
> >
> > UV has been considered a culprit in fading because, I believe, it
> > carries more energy than the longer wavelengths. That said I think
> > conservators have become even more conservative in recent years,
> > treating any and all light exposure as damaging to artwork over the
> > long hall. Somewhere I saw a calculation of how much energy the Mona
> > Lisa would be exposed to if every other person who looked at it over
> > the course of a year took a flash picture of it. I don't remember the
> > final calculation but it was equivalent to leaving the painting out in
> > the sun for a considerable length of time.
> >
> > -greg
> >
> >
> > On Fri, 23 Feb 2001, Judy Seigel wrote:
> >
> > > Bob, do you mean that in ordinary home situation, that is, not museum lit
> > > all day, but interior with some artificial light, pigments that have top
> > > rating fade? I have fluorescent ceiling light over computer MANY hours a
> > > day, at press time maybe 16 or so -- a small painting in this light for,
> > > probably 25 years... hasn't faded that I NOTICED, and not under glass.
> > >
> > > ????????????????????????????
> > >
> > > Judy
> > >
> >
> >
> >
> > ----------
> >
> > Hope for the best, but be prepared for the worst.
> >
> > US ARMY SURVIVAL MANUAL
> >
> > ----------
> >
> >
>

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