Shannon,
It depends. Of course, you expected this
answer! First, you need to look at the spectral curves for transmission of
the two different grades of plexi. Typically, (and I can't speak for the
specific plexi you are considering as you did not provide manufacturer details),
the regular plexi filters something like 95% of UV (not to provide UV
protection, but to allow the plexi itself to be less degraded by UV) and the
special UV filtering filters something like 99% of UV. But the UV
filtering also filters some of the violet light, which is high energy but
visible. This shifts the color balance a bit, but probably not
noticeable. So, on the surface, 95% versus 99% filtering looks pretty
good. But, looking at transmittance, the regular lets through 5% UV and
the special lets through 1%. That means the regular lets through 5 times
more UV than the special. However, it also eliminates 19 out of 20 parts
of UV, just not 99 out of 100 parts.
So, the second question is what is inside the
bonnets? It is particularly light-sensitive? If so, it may be worth
the extra cost for the special plexi. If not, it may not be worth
it.
Third, what is the light source you are trying to
filter? If it is MR-16 bulbs, or other incandescent sources, there is so
little UV that regular plexi is probably fine for all objects, so long as it
filters at least 90% of UV. If it is daylight, special plexi may be best
if the objects are light sensitive.
I wish there was a one-size-fits-all answer, but it
depends!!
Marc
American Conservation Consortium,
Ltd.
4 Rockville Road
Broad Brook, CT 06016
www.conservator.com
860-386-6058
*Collections Preservation Consultation
*Conservation Assessments &
Surveys
*Environmental Monitoring & Low-Tech Control
*Moisture
Management Solutions
*Collections in Historic Structures
*Collections Care
Grant Preparation
*Conservation Treatment of:
Furniture
Painted Wood
Horse-Drawn Vehicles
Architectural Interiors
Decorative Objects & Folk Art
Marc A. Williams, President
MS in Art
Conservation, Winterthur Museum Program
Former Chief
Wooden Objects Conservator, Smithsonian Institution
Fellow, American Institute for Conservation (AIC)
----- Original Message -----
Sent: Friday, May 27, 2011 3:57 PM
Subject: [MUSEUM-L] Plexi Question
I am about to order plexi bonnets and there is quite a
price difference between the “Cast Regular Museum” and “Cast UV OP-2 Museum.”
Is it worth spending the extra money to get the UV OP-2?
Any advice would be helpful!
Thanks.
Shannon
Bailey
Assistant
Director
World Chess Hall of Fame and
Museum
P.O. Box
4797
Saint Louis, MO
63108
C:
314.578.2922
F:
314.454.5778
[log in to unmask]
www.worldchessmuseum.org
Become our Fan on Facebook!
www.facebook.com/ChessMuseum
To unsubscribe from the MUSEUM-L list, click the following
link:
http://home.ease.lsoft.com/scripts/wa.exe?SUBED1=MUSEUM-L&A=1
To unsubscribe from the MUSEUM-L list, click the following link:
http://home.ease.lsoft.com/scripts/wa.exe?SUBED1=MUSEUM-L&A=1