2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P44 CAN wE ENSuRE SAFER ENVIRONMENT
FOR CuLTuRAL hERITAGE?
IVAn MAŠEK a and ZDEnA ROSICKá b
a Brno University of Technology, Faculty of Chemistry, Purkynova
118, Brno, 612 00, Czech Republic,
b Universita of Pardubice, Faculty of Restoration, Jiraskova
3, Litomysl, 570 01, Czech Republic,
masek@fch.vutbr.cz
Introduction
Books should be kept in a stable environment. This is
best effected by preventing temperature changes around the
collection or ensuring that any changes made will be very
gradual. In addition, books in fragile condition should be
placed in close-fitting, nearly airtight enclosures. They protect
materials from dust and airborne pollutants; reduce the
exchange of moisture between the paper in the books and the
air. Slow changes in air temperature around a book will not
cause harm, even sudden upward temperature changes are
not too damaging. In case the book in a protective enclosure
is suddenly cooled, water will condense on the enclosure’s
interior walls when the temperature drops bellow the dew
point of the air within the enclosure.
The climate maintained in a library is the result of a
compromise between the needs of the readers and the staff,
maintenance demands and the structure of the building which
should result in minimizing the deterioration rate of the collection.
It is believed that that the rate of deterioration of library
materials doubles with every 10°C increase of temperature.
This belief is based on the fact that the speed of chemical
reactions depends in large part of temperature. Recommended
temperature ranges for a variety of library materials.
A certain amount of relative humidity is necessary for
paper to retain its flexibility but scientists disagree about
the optimum relative humidity desirable because increased
moisture content increases the rate of deteriorative chemical
reactions and mold will grow. The recommended level
of relative humidity is a compromise among several require-
ments:
•
•
•
level of moisture high enough to maintain flexibility,
level low enough to slow deterioration of materials and
control insects and mold,
level that will do no structural harm to library buildings
due to condensation in cold weather.
Molds cause a downy or furry growth on the surface of
organic matter; they can develop on leather, cloth, paper, etc.,
especially in the presence of relatively high heat and relative
humidity. Every cubic meter of air contains thousands of
molds spores that cover surface of library objects. Mold and
mildew eat books and papers. The cellulose, adhesives and
starches in the sizing provide a source of nutrition that enables
the fungi to excrete digestive enzymes that convert these
materials into forms they can digest. Molds usually attack
bindings before the text block because it lands on the binding
s423
first, the cellulose is more difficult to digest and the text block
is tightly closed.
Salvage of Flood Damage Papers
It should be noted that flood damage to some items may
be irreversible. The treatment of objects of high monetary,
historic or sentimental value should only be performed in
consultation with a conservator.
Many people are sensitive to mold and some mold species
are toxic. The best way to prevent or stop the outbreak
of mold is to remove items from environmental conditions
that encourage mold growth: high temperature, high relative
humidity, stagnant air and darkness. If wet and moldy materials
cannot be dried immediately they may be stabilized by
freezing. Placing damaged items in a personal or commercial
freezer will not kill mold, however, it will put the mold
in a dormant state until time and the appropriate treatment
environment are available. Active mold look fuzzy or slimy.
Dormant mold is dry and powdery. Mold which remains
active after freezing or after the host material appears dry
may be treated with exposure of 1–2 hours to ultraviolet radiation
from the sun. Extreme caution must be exercised when
treating material outdoors: too much radiation will accelerate
deterioration and may cause fading, wind may cause
physical damage, and high relative humidity or condensation
caused by rapid temperature changes may also exacerbate
mold growth. Dormant mold spores will reactivate as soon as
conditions are favorable. They should, therefore be removed
from items and may be brushed or vacuumed away.
There are both chemical and non-chemical means to kill
mold. Effective treatment can be fungi-static or fungicidal.
Fungi-static treatments are those preventing the mold spores
from germinating but do not kill the mold. Freezing is one of
methods. Fungicidal treatment kills the mold and its spores.
no safe large-scale treatment imparts lasting or residual mold
control. That is why it is important to change the environment
so it inhibits mold growth. In addition, there is some evidence
that books and papers treated with fungicides may be more
susceptible to mold after treatment than they were prior to
the outbreak.
Fig. 1. Flood damaged book