There are no artifacts in the cases.  It is a transparency display.   We
do think the problem is heat build-up, and we are removing the end caps
to let heat escape.  We'll know more by next week.

Thank you for your response.

O
Olivia S. Anastasiadis, Curator
Richard Nixon Library & Birthplace
18001 Yorba Linda Boulevard
Yorba Linda, CA  92886
(714) 993-5075; fax (714) 528-0544; e-mail:  [log in to unmask]

On Wed, 3 Sep 1997 01:47:01 -0800 "Jack C. Thompson" <[log in to unmask]>
writes:
>This question is a puzzler.  UV shields cut out ultraviolet light;
>infrared
>light (from the opposite end of the spectrum) is responsible for heat
>build-up.  But plastic holds heat in a system longer than, for
>instance,
>glass.
>
>So, plastic UV shields can be expected to allow greater heat build-up
>in a
>fluorescent light fixture.  On the other hand, the shields are not
>sealed;
>heat can be expected to escape readily from the ends of the shields.
>
>You state that the shields were recently installed and that the
>facility
>director has determined that the shielded tubes are burning out 60-70%
>faster than those without shields.
>
>My experience is that fluorescent bulbs burn for years, with or
>without shie=
>lds.
>
>Before making a decision one way or the other about the UV shields, I
>would
>check the ballasts in the lamps in question and also check the
>stability of
>power from the transformer supplying the site.  I have noted that low
>voltage has a very deleterious effect on the life span of fluorescent
>lamps.
>
>You don't say so, but your description suggests that the lamps in
>question
>are inside exhibit cases.  This is not good.  If the ballasts are
>inside
>the cases there can be a great deal of heat build-up just from the
>ballasts
>and this can cause damage to the fluorescent bulbs (and the
>artifacts....)
>I once worked at a site where it was so hot that fluorescent lamps
>turned
>off about 3:00 pm each day.  And so did the crew.
>
>There is an additional danger if fluorescent light ballasts are inside
>the
>cases.  Ballasts are transformers; wire wrapped around metal plates in
>tar
>or some other nastier non-conductive material.  If a ballast becomes
>hot
>enough it will ignite creating a dense, black, particulate laden, foul
>smelling, hazardous smoke; dangerous to people in the area.  It
>doesn't do
>the artifacts in the case any good either.
>
>Jack
>
>>Date:    Tue, 2 Sep 1997 19:27:49 EDT
>>From:    "Olivia S. Anastasiadis" <[log in to unmask]>
>>Subject: Re: UV tubes
>>
>>We recently installed Filter-RayUV Shields from Light Impressions.
>Our
>>facility director has noticed that the fluorescent tubes we sleeved,
>with
>>these u-v shielding acrylic tubes, are burning out 60% to 70% sooner
>than
>>they would=EDve without the shields.  He suspects that the heat
>buildup is
>>causing our fluorescent tubes to burn out sooner.  Further, the
>display
>>case where we are using this product doesn=EDt have electronic
>ballasts for
>>the fluorescent we use.  Is this a contributing factor?
>
>(snip)
>
>>Olivia S. Anastasiadis, Curator
>>Richard Nixon Library & Birthplace
>>18001 Yorba Linda Boulevard
>>Yorba Linda, CA  92886
>>(714) 993-5075; fax (714) 528-0544; e-mail:  [log in to unmask]
>
>
>Jack C. Thompson
>Thompson Conservation Lab
>7549 N. Fenwick
>Portland, OR  97217
>
>voice/fax: 503/735-3942
>
>www.teleport.com/~tcl/
>