Linda McAllister wrote:

> Our museum owns a large map that was given to Howard Hughes by Kathryn 
> Hepburn [approx. 5'x5']   We'd like to either frame this piece or put 
> it between glass.  Can anyone suggest materials to use or ways of 
> displaying it?
>  
>

When I saw the first response to your inquire: creating a surrogate; I 
though how enlightened this group has become. 


As I tell all of my clients who want to display their artifacts 
permanently, you will be exposing them to light 100% of the time, but 
you will be using it 1% of the time, so most of the deterioration of the 
dyes (fading) and paper (yellowing) will be without the benefit of 
appreciating the work.  So, basically you are throwing the artifact 
away, for no real reason.  An institution would be different because 
viewing would be up to 5-10%, but still most of the life of the artifact 
is being thrown away. 


Cutting out UV light is commendable, but all light does damage.  If the 
energy is used to illuminate, the colorants are absorbing portions of 
the energy, and, thus will be damaged by the absorbed energy.  Cutting 
UV eliminates an illuminant we can't see, that is much more damage than 
visible light.


I make surrogates for institutions that would otherwise be putting the 
works in hostile environments such as exposed to the elements in an 
historic house with almost year round expose to outside conditions such 
as rain, high heat  & humidity, freezing conditions, etc.  I routinely 
make very good surrogates for institution's that want to make a loan but 
can't lend the original for any number of reasons.  Some traveling 
exhibition will be on almost continuous display.  Some travel for 3+ 
years, at light levels that are stipulated, but not always met.


Thomson's (Museum Environment) recommendations for works on paper were 
for 3 months at 50 lux, every 5-6 years, for 500 years.  That is a 
minimum lifetime of 6.5 Mlux-hrs until the noticeable loss of colorant 
or yellowing.  Today we assume this to be 20% loss of one colorant.  
Some artifact will fail before this because they have already been 
degraded and some will last far longer.  One of the main problem being: 
quite often we don't know how susceptible an artifact will be until we 
see some loss.  Some artifacts start life in the highly fugitive group, 
such as watercolors, cyanotypes, some albumen prints, etc.  Printed maps 
may fall into this group, if they have fugitive dye(s).  How do we know 
that?  Only if fading has occurred, or if similar materials show 
damage.  Generally, maps don't fall into the most fugitive group, but 
they can.


Putting work on the wall indefinitely, throws 90-95% of their lifetime 
away.  Allowing patrons to see an original for 5-10 years, is not a 
valid trade-off for showing patrons the artifact for 500+ years, under 
condition that will facilitate that lifetime.  There are two methods of 
achieving a 500+ lifetime (a) 3 months at 50 lux every 6 years or (b) 
the display of a surrogate.


To me... this is the "instant" wisdom of not exposing the original on 
permanent display.   [Why assume permanent display?  Why would one ask, 
if they had day-to-day experience with changing exhibitions and those 
options?] 


Artifacts should never be sandwiched between glass or Plexiglas, even 
though that would be easiest method for such a large map.  Separating 
the glazing from the original is the only accepted method.  The map 
should not be mounted because that will be altering the original, and, 
if mounted, reversing the process could be problematic and expensive (in 
the future when it starts to fail).  Mounting can be done well by 
conservators, but it will be expensive.  The only viable framing method 
for the original, remaining, is hinging and matting.  If the artifact is 
a surrogate, any method can be used.  More than one copy of the 
surrogate can be made, often at substantially reduced cost. 


Never scan using blueprint or drawing scanners.  It is quite right that 
they can cause hard wrinkles at a minimum and tearing at a maximum.  
Those machines are made for modern paper that is strong and flat with 
smooth (undamaged) edges.  I would capture such a map using a 
BetterLight scanning back using a view camera and NothLight HID lighting 
<http://www.betterlight.com/hid_copylights.html>.  It would have to be 
captured in sections to achieve 450-600 ppi resolution.  I usually scan 
at twice the viewed resolution because of many factors including the 
Nyquist Digital Sampling equation.  Humans can't resolve better than 
about 300 ppi, even less for older eyes like mine, unless aided by 
reading glasses.  I would print at 3600 ppi is using the an Epson 9600 
with Ultrachrome (pigmented) inks, that are stable for 65-110 years 
(under glass) depending on paper, which would be governed by the 
original surface texture of the artifact.


Tim Vitale
Paper, Photographs &
Electronic Media Conservator
Film Migration to Digital Format
Digital Imaging & Facsimiles
Preservation & Imaging Consulting
Preservation Associates
1500 Park Avenue
Suite 132
Emeryville, CA 94608

510-594-8277
510-594-8799 fax
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