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<h1>The Invasion of the Giant Spore</h1>
<address>SOLINET Preservation Program * Leaflet Number 5<br>
by Sandra Nyberg<br>
1 November 1987
</address>
<p>It's a quiet, peaceful day. You stroll complacently
through the aisles of books, contemplating the neat rows of
colored cloth and leather. A bit of sunshine glimmers
through the distant stacks. A little tune is wandering
through your thoughts. Suddenly, a shiver runs down your
spine. You stop. Something is wrong; you sense danger.
Slowly you turn and peer down the rows of books, half afraid
of what you will find. You cautiously step forward, and
there it is, lurking in the dark, slowly creeping down a row
of books. It slithers from one volume to the next,
maliciously victimizing innocent and helpless books. The
air is filled with a vaguely unpleasant odor. Books become
untouchable--they are slimy, they are furry, they are
distinctly icky. Who knows, it may spread to the carpet,
the walls, the curtains, the chairs, even your office; it
may take over the whole library! It's the attack of the
awful mold!</p>
<p>Before you panic, calm down. Although it won't be easy,
mold can be stopped. You can protect yourself from it.
This leaflet will provide you with some effective weapons to
use against mold. Before we come to the weapons, though, we
need to analyze our foe. What is mold? Where does it come
from? What does it do to books and paper?</p>
<h2>I. What is Mold? And Where Does It Come From?</h2>
<p>Mold is a type of fungus. It grows on surfaces in masses
of branching threads which resemble dense cobwebs. The
fertile threads, those which produce spores, often stand up
from the surface into the air to release their spores.
Spores are carried by air currents or by adhering to insects
or animals. Active mold can be any color, depending on the
species and the substrate upon which it is growing. Mildew
is another type of fungus, similar in structure to mold, but
distinct as one species of fungus is distinct from another.
The terms "mildew" and "mold" are not interchangeable; they
are most often used in the common names of various fungi.
Fungi is a kingdom of organisms, with a single division,
Mycota. The fungi have traditionally been classified with
plants but are now considered a distinct group of organisms.
Unlike plants, which produce their own food, fungi absorb
nutrients from dead or living organic matter. Fungi also
lack photosynthetic pigments. There are over 100,000 known
living species of fungus, some of which are beneficial to
mankind. Mycologists estimate that there may be as many as
200,000 more unidentified species of fungus. Yeasts, molds,
mildews, rusts, and mushrooms are types of fungus.</p>
<p>The spores of fungi that become mold or mildew are always
present in the air and on objects. When the temperature and
moisture in the environment are suitable for germination,
the fungus spore bursts and grows into a thread-like
filament called a hyphae. Using the object it is growing on
as a food source, the hyphae form a mass, called a mycelium,
and within a short time begin to produce spores. At
maturity, spore sacs burst and release spores, which
eventually land on other material and begin the reproductive
cycle again.</p>
<p>In libraries, optimum conditions for mold and mildew
development exist when temperature is above 70° Fahrenheit
and relative humidity is above 70%. However, some common
molds can grow at temperatures as low as 50° Fahrenheit and
in relative humidities as low as 45%. It is also possible
for molds to begin growing in conditions of high relative
humidity and temperature and then continue growing in
environments with significantly lower relative humidity and
temperature.</p>
<h2>II. What Does Mold Do To Books and Paper, and to
People?</h2>
<p>Basically, mold and mildew eat library materials. Books
and paper provide a source of nutrition through such
components as cellulose, starch adhesives, and starches in
sizing. The mold and mildew excrete digestive enzymes that
allow them to eat starches and cellulose, grow, and produce
more spores. Cellulose in paper is difficult to digest, so
many molds prefer the starch in cloth-coverings on books and
in paper sizings. In book collections, mold is often noted
on the bindings long before it grows on textblocks. Molds
grow rapidly, although they generally grow at a slower rate
when relying on only cellulose for food.</p>
<p>Conditions that promote mold and mildew growth (high
humidity and warm temperatures) will also, in and of
themselves, increase the rate of book/paper deterioration by
accelerating the aging process and the formation of acids.
Furthermore, mold and mildew can irreversibly stain books
and paper. Such stains destroy text and images. Books and
paper can also be seriously softened and weakened by mold,
making them difficult to handle.</p>
<p>Mold and mildew can have an adverse effect on people.
Those with allergies, asthma or other respiratory problems
should stay away from infested areas, as many fungi will
seriously irritate and inflame lungs. Some fungi can cause
skin and eye irritation and infections. Prolonged exposure
to germinating molds in closed areas (which exist in many
library collections) can damage the lungs, mucous membrane,
cornea, respiratory tract, stomach, intestines, and
skin.</p>
<h2>III. The Repulsion of the Giant Spore, or How To Rid
One's Collection of Mold.</h2>
<p>Before describing processes that will kill mold, I want
to stress the fact that the ONLY way to get rid of mold
permanently and to keep mold from your collections is to
control the environment within non-hazardous ranges of
temperature and humidity. You may use chemicals to kill
mold, but the only safe and effective way to keep it from
coming back is to modify the environment which contributed
to the development of mold. So before I discuss methods of
killing mold, I will describe the environment necessary for
the prevention of mold formation.</p>
<h3>III.A. What is a Mold-Preventive Environment?</h3>
<p>There are a number of factors which influence the growth
of mold: environmental humidity and moisture content of
materials, temperature, air circulation, light, and the
chemical composition of potential substrates. Each of these
is discussed here in relation to the environments which will
inhibit or promote mold growth.</p>
<h4>III.A.1. Humidity.</h4>
<p>The most important environmental factor to control is the
amount of moisture in the air and consequently in books and
paper. Books and paper naturally contain a certain amount
of water. They are hygroscopic, so that when relative
humidity goes up, they absorb water to achieve equilibrium.
At 50% relative humidity, the moisture content of paper is
approximately 7%; at 70% relative humidity, it is
approximately 10%. Moisture enables mold to absorb
nutrients from book and paper substrates, so the more
moisture a book contains, the greater are the chances for
fungus spores to germinate at room temperature. The
potential for mold or mildew development on wet books is one
important reason for quick freezing of books damaged by
water.</p>
<p>Relative humidities above 70% can easily lead to mold
growth; for safety, it is generally recommended that
libraries keep their relative humidity below 65%. Relative
humidity below 40%, however, can cause books and paper to
become fragile from dryness. Hence the acceptable range is
45% to 65%. It is possible, however, that some molds can
begin growing at 70% relative humidity or higher and then
continue growing at relative humidities of less than 70%.
Because of this, new acquisitions should be checked for mold
and treated, if necessary, prior to storing them with the
rest of the collection.</p>
<p>Consistency is also important within the 45% to 65%
range. As books and papers absorb or release water into the
atmosphere with changes in relative humidity, they also
change their shapes. They expand or contract, although
different parts of a book will do so at different rates, as
will different types of paper. For example, a vellum
binding may expand quickly as it absorbs water, but the
paper inside will expand more slowly, and the adhesive used
in binding may expand at an intermediate rate. Fluctuations
in humidity, when necessary due to, for example, seasonal
changes, should be slow and carried on over time. Generally,
it is recommended that relative humidity remain at 50% with
a maximum change of plus or minus 5% per month.</p>
<h4>III.A.2. Temperature.</h4>
<p>Most molds thrive at warmer temperatures. When combined
with high levels of humidity, temperatures of 70 to 75°
Fahrenheit will cause mold to develop. Temperatures below
freezing will not kill mold, but they do make it dormant.
Few molds will be active at temperatures of less than 50°
Fahrenheit. Mold can also grow in conditions up to 140°
Fahrenheit. High heat will kill mold, but it will also
severely damage library materials.</p>
<p>For patron comfort, temperatures of 70° Fahrenheit plus
or minus 2° are acceptable in libraries, provided relative
humidity is kept at 50%.</p>
<h4>III.A.3. Air Circulation.</h4>
<p>In conjunction with humidity and temperature control,
adequate air circulation will help prevent mold growth. Air
circulation helps control moisture levels through
evaporation.</p>
<p>Installing a heating/ventilation/air conditioning (HVAC)
system with humidity control can solve all three problems of
humidity, temperature, and air circulation at the same time.
Such systems are not easy to install, simple to maintain, or
inexpensive. But they provide the most effective means of
preserving your collections. Not only do suitable HVAC
systems assist in mold prevention, but they also stabilize
the environment and hence eliminate the distortion of
materials due to fluctuating temperature and humidity.
Furthermore, maintenance of a stable environment slows down
processes of deterioration caused by acid, light, and
pollution. An HVAC system's control of the environment can
also help in controlling insect infestations.</p>
<p>If you cannot install or improve an HVAC system in your
library, there are a few alternatives which, although not as
effective, will help. Fans can be installed to improve air
circulation. They are best placed near outside walls and
close to floor level. Portable dehumidifiers can be used,
particularly for localized problems. Although you can
invest in several units, portable dehumidifiers tend not to
be as effective in large spaces as a centralized HVAC system
with humidity control. Fans and vents in attics will
increase air circulation by pulling air through the
building. This is particularly useful when it is necessary
to leave windows open. Desiccants (such as silica gel) can
be used to absorb moisture in humid environments. They
should not, however, be used where young children are able
to reach them because ingestion may be dangerous.
Desiccants are most useful for localized problems,
especially those that can be contained in a small, enclosed
space.</p>
<h4>III.A.4. Light.</h4>
<p>Sunlight, and in particular ultra-violet radiation,
generally inhibits mold growth. The Virginia State Library
observed a direct connection between the rate of mold growth
and the presence of light during several outbreaks in its
collections between 1978 and 1980. It was found that more
light correlated with slower growth rates. The relationship
between light and mold growth is discussed further in
section III.B.1.c. Sunlight and ultra-violet radiation,
however, cause serious fading of library materials and can
speed up chemical reactions leading to the formation of
acids in paper; hence prolonged increases in the exposure of
library materials to light are not recommended.</p>
<h4>III.A.5. Chemical Composition.</h4>
<p>Mold growth can also be affected by the chemical
composition of the book or paper substrate. Many fungi
prefer slightly acidic material. They will also interact
with non-cellulose matter within paper, such as iron
particles, leading to staining and further deterioration.
The chemical composition of most library materials is not
something which can easily or even should be changed. But it
does make some parts of collections more susceptible to mold
growth than others.</p>
<h4>III.A.6. Miscellaneous Environmental
Modifications.</h4>
<p>There are several modifications that can be made to the
building or its internal environment which will assist in
preventing mold outbreaks.</p>
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<ul>
<li>Don't shelve books directly against an outside wall.
Due to temperature and humidity differences between inside
and outside environments, moisture may develop along walls.
Allowing air to circulate against the walls will enable the
moisture to evaporate.
<li>Keep the quantity of indoor plants to a minimum and
don't allow indoor planted areas.
<li>Waterproof basements and walls below ground level. And
use water-sealant paint on floors and walls.
<li>Place or adjust outside gutters and drains so that water
does not collect near the outside walls. Check gutters and
drains regularly to avoid clogs. Place lawn sprinkler
systems so that they do not soak outside walls.
<li>Regularly inspect your collection for mold or mildew.
This will allow you to catch any infestation before it
becomes large. And continue to monitor potentially
hazardous areas until the environment can be stabilized in
an appropriate state.
</ul>
<h3>III.B. What Can You Do If You Have a Mold
Outbreak?</h3>
<p>There are a number of things you can do when faced with
mold in your collection, but first you need to determine
what has caused the mold to grow. Check the humidity and
temperature. Chances are good that, for a large
infestation, the cause at least partially lies there. When
the Denver Public Library found mold in its off-site storage
facility in 1984 (it was visible on approximately one-third
of the books there), relative humidity was 60% and
temperature was 78° Fahrenheit. Also look for a source of
water, such as an unnoticed leak, a broken window, moisture
along outside walls. A third place to check is the
heat-exchange coils in the heating/air conditioning system;
they are a prime area for fungus growth and spore
distribution. Clean them with a normal fungus-killing
household cleaner. You need to pinpoint whatever caused the
mold to develop and then fix it, because until you solve
that problem, mold will continue to grow, no matter how
often you treat the affected material.</p>
<p>Your second response should be to isolate affected
materials. If a small quantity of books is moldy, seal them
in air-tight plastic bags. If the infestation is large,
quarantine the area. You should wear rubber or plastic
gloves and a dust or filtration mask whenever handling moldy
materials. Isolating moldy books and papers serves two
purposes: it minimizes the spread of mold, and it protects
those persons who may have allergies or respiratory problems
from harm.</p>
<p>Third, do what you can to increase air circulation and
lower humidity. Open windows, provided it is not raining
outside and the relative humidity outside is lower than that
inside. Set up fans to increase air circulation. Set up
dehumidifiers or re-adjust the HVAC system to lower the
relative humidity. If you have a thermostat-controlled
cooling system or one which simply lowers the temperature of
outside air prior to ventilating it through the building,
turn it off. This kind of "air conditioning" or cooling
system does not provide humidity control and will in fact
increase internal relative humidity because cold air cannot
hold as much water as warm air. Furthermore, the moist
heat-exchange coils in this system may be providing a
fertile ground for the growth of mold, the spores of which
are then distributed throughout the building via its
ventilation system.</p>
<p>Every library and archives should have at least one tool
for measuring relative humidity--a hygrometer, sling
psychrometer, or hygrothermograph. Used regularly and
properly, these tools can alert you to increases in relative
humidity before mold growth begins so that you may
effectively modify the environment to prevent mold. During
an outbreak, hygrometric tools should be used regularly (two
to four times a day) to monitor the environment and the
effectiveness of your modifications, and to make
readjustments as necessary.</p>
<p>After you have readjusted the environment, you can look
at available means for killing mold and cleaning the
collections. There are both chemical and non-chemical means
to kill mold. Effective treatments can be fungistatic or
fungicidal. Fungistatic treatments are those that prevent
the mold spores from germinating, but do not kill the mold.
Freezing is one such method. Fungicidal treatments kill the
mold and its spores. No safe large-scale treatment,
however, imparts lasting, or residual, mold control. That is
why it is so important to change the environment so that it
inhibits mold growth. Furthermore, 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.</p>
<p>In order to judge the effectiveness of the following
chemical and non-chemical treatments, a number of questions
should be asked about each. Is the treatment fungicidal or
fungistatic? Can it damage books or paper during
application or by leaving behind harmful residual chemicals?
Is the treatment toxic to humans and how is such toxicity
accounted for during application? Does the treatment act
effectively in a short period of time, with low cost and
reasonable implementation procedures (transportation,
quarantine needs, equipment, etc.)?</p>
<h4>III.B.1. Non-Chemical Treatments.</h4>
<p>Non-chemical treatments to kill mold consist of
procedures which do not involve the application of chemicals
to the books or paper in solid, liquid, or vapor form.
Usually, this involves some temporary modification of the
environment. Non-chemical treatments are preferred to
chemical treatments by many because they don't interfere
with the chemical composition of the materials, they do not
leave residues in treated materials, and they are non-toxic
to humans. Many non-chemical means have been discussed and
experimented with; I mention the more commonly known of them
here.</p>
<h5>III.B.1.a. Freezing</h5>
<p>Freezing involves placing the moldy books in an
atmosphere of below freezing temperatures. It is a
fungistatic, not fungicidal treatment. It may present an
option for halting the spread of mold while you evaluate
other methods for killing the active mold.</p>
<h5>III.B.1.b. Gamma radiation</h5>
<p>Gamma radiation has been used to sterilize surgical
equipment and food. Experiments in irradiation of books to
kill mold have been conducted by Johns Hopkins Medical
Institutions and by the State Central Archives of
Czechoslovakia. Although it does kill mold and does not
leave residues, there is evidence that gamma radiation
softens leathers and adhesives and breaks down the internal
structure of paper. The folding endurance of paper
decreases with higher levels of radiation. Mold can be
killed at lower levels of radiation when heat is applied;
heat, however, can also decrease paper strength. Studies
indicate that the effects of individual radiation exposures
add up, hence repeated disinfection of books and papers with
radiation is not recommended. Special chambers and
corresponding operator training are necessary for
irradiation, sources which are not easily accessible or
necessarily affordable for most libraries. Because of the
possibility of damage and the difficulty of accessing
equipment, gamma radiation as a fungicide for books is not
commonly used or recommended.</p>
<h5>III.B.1.c. Ultra-violet light</h5>
<p>Ultra-violet light, as mentioned earlier, inhibits mold
growth and may kill mold. It is not, however, recommended
as a full-scale treatment for mold on books and papers
because the amount of exposure necessary to kill mold would
induce fading and accelerate aging. However, it has been
suggested as a possible step in treating small, localized
outbreaks. Active mold can be wiped or vacuumed from the
book, and the book then placed outdoors, fanned open, in the
sun, for a day or two. Do not leave books and papers outside
overnight, as temperature changes may cause condensation to
form. If the book is placed back into a suitable
environment, the combination of removing the visible mold
and allowing the book to dry out in the sun may halt the
further growth and spread of the mold. Books should not be
placed outdoors if the relative humidity is above 65%. This
process needs careful and continued monitoring, and may not
be feasible for a mold outbreak affecting a large quantity
of material.</p>
<h4>III.B.2. Chemical treatments.</h4>
<p>Using chemicals to kill mold involves the same concerns
and criteria discussed earlier. And, although many
chemicals can kill mold, environmental conditions still need
to be modified and improved in order to prevent recurrence
of the mold.</p>
<p>Unlike non-chemical treatments, there is a much greater
awareness of toxicity to humans and residual damage to books
when applying chemical fungicides. Several chemicals which
are fungicidal are not used on book collections because of
their toxicity and instability: included here are mercuric
chloride, highly toxic and legally restricted in the U.S.;
hydrogen sulfide, an explosive; and methyl bromide, which
leaves an irreversible foul odor, softens adhesives, and is
toxic.</p>
<p>Many chemical fungicides can impart limited residual
control if applied directly to a document through aqueous
means (instead of killing mold through exposure to toxic
fumes, documents are soaked in solutions which contain
fungicides). Aqueously-applied fungicides cannot be rinsed
out of the documents, though, if any residual control is
desired. Aqueous application of chemicals to books and
paper is time-consuming and requires extensive knowledge of
chemicals and their effects on paper and book materials.
Only a conservator should aqueously apply chemical
fungicides to material in library and archival collections.
If the recommended or available fungicides are chlorinated
substances, as many are, they will break down in paper over
time to form the highly destructive hydrochloric acid. This
breakdown is accelerated by impurities in most papers, such
as iron and copper. Examples of fungicides which should be
applied only by a conservator include salicylanilide,
pentachlorophenol, and dichlorophene.</p>
<p>Only a knowledgeable conservator will know how to test
the stability and effectiveness of aqueously-applied and/or
chlorinated fungicides in the paper to be treated. Even if
a fungicidal chemical is stable in the particular paper, it
will need to be used in appropriate and often very low
concentrations (for example, chlorinated chemicals are often
applied in concentrations of 0.1% of the paper's weight).
Because they are time-consuming and require significant
pre-testing prior to application, aqueous and/or chlorinated
treatments are not feasible for large-scale infestations.
Some will work, though, on single items. The high cost
involved (especially labor cost) tends to limit the use of
aqueous treatments to rare materials, items whose intrinsic
values make the expense worthwhile.</p>
<p>In contrast to the item-specific application of aqueous
and/or chlorinated fungicides are several vapor treatments
which may be applied on a large scale in libraries and
archives as well as to just a few items. The aqueous
treatments discussed above have the ability to impart some
residual mold control, but none of the vapor treatments
allow for residual control. However, these vapor treatments
are easier to use, can be used for large or small
infestations, and can be safely applied by non-conservators,
under the appropriate conditions.</p>
<p>Below I describe the more commonly known and discussed
chemicals used for killing mold in libraries and archives.
When included in my description, implementation procedures
for these chemical treatments are aimed only at application
to general book or record collections. Consulting a
conservator is recommended prior to treating large mold
infestations in rare book or manuscript collections.</p>
<h5>III.B.2.a. Thymol</h5>
<p>Thymol (isopropyl-meta-cresol) is a phenol. It is in
crystalline form at room temperature, and sublimes to vapor
when heated above 120° Fahrenheit.</p>
<p>Thymol is toxic, and can be absorbed through the skin, by
inhalation, or by inadvertent ingestion. The major hazard to
those using thymol for fumigation is inhalation. Thymol has
a pungent odor, however, which serves as a good warning to
those working with it. Symptoms of overexposure include
gastric pain, nausea, vomiting, and central nervous system
overactivity. Very high levels of exposure could result in
convulsions, coma, and cardiac or respiratory arrest. Long
term effects from repeated exposure include liver and kidney
damage, and dermatitis.</p>
<p>To use thymol effectively and safely as a fungicide, a
sealed cabinet is necessary. Sources of instructions for
building or modifying cabinets to use with thymol are
included in the bibliography. Conservators and others
handling treated materials and thymol should wear neoprene
or butyl rubber gloves and, when opening the chamber after
treatment, should wear a respirator with an organic vapor
cartridge. Care should be taken to limit human exposure to
thymol to a minimum.</p>
<p>Studies have shown that paper will discolor (yellow) if
treated with thymol and then exposed regularly to light.
Some authorities have declared thymol to be fungistatic but
not fungicidal in their tests. Others, such as Barry Byers
and Mary-Lou Florian, claim that it is fungicidal. The
effectiveness probably varies with the type of fungus and
the application procedure. The following procedure is that
described by those who found the treatment with thymol to be
fungicidal.</p>
<p>Before fumigation, wipe visible mold from bindings. Fan
books open and stagger flat paper on the shelves in the
cabinet. Place thymol crystals in dishes in the cabinet and
heat them with 15 to 20 watt light bulbs. The ratio of
thymol to area is roughly 1 dish with 5 grams of thymol
crystals and a corresponding light bulb for each 9 cubic
feet (.25 cubic meters) of cabinet. The cycle is 2 hours of
heating with light bulbs on, 22 hours with light bulbs off,
for three consecutive days. The cabinet is kept closed for
the entire cycle, to allow the vapor to penetrate. Upon
completion, the cabinet is opened and books/papers are
aerated for several hours. Some cabinet designs incorporate
exhaust systems, which make aerating safer and easier at the
end of the cycle.</p>
<p>Thymol can also be used in spray or mist forms, but is
generally not because of the greater exposure on the part of
the person applying the thymol. In such situations,
ortho-phenyl phenol is usually substituted.</p>
<p>Many libraries and archives no longer use thymol because
of health hazards. Those who are considering its use should
read Deborah Nagin and Michael McCann's "Thymol and O-Phenyl
Phenol: Safe Work Practices" from the Center for
Occupational Hazards.</p>
<h5>III.B.2.b. Ortho-phenyl phenol</h5>
<p>Ortho-phenyl phenol is a solid at room temperature. It
is usually mixed with an alcohol, such as ethanol, for
aqueous or spray application. When applied as a vapor, it
is much slower acting than thymol, but also much less of a
health hazard. Many recommend that o-phenyl phenol be
substituted for thymol in general use.</p>
<p>Although it is a phenol, like thymol, o-phenyl phenol is
not absorbed through the skin. It may cause some skin
irritation with prolonged contact. It can cause eye
irritation, and inhalation of the powder can cause upper
respiratory irritation. Repeated and long-term exposure
could lead to kidney damage. Respirators with organic vapor
cartridges should be worn when fogging or spraying with
o-phenyl phenol, as should neoprene or butyl gloves when
handling o-phenyl phenol and/or treated items. Care should
be taken to wash hands when working with o-phenyl phenol,
even if wearing gloves, to avoid inadvertent ingestion.</p>
<p>As with thymol, there is some debate among experts as to
o-phenyl phenol's effectiveness as a fungicide. Some
experts feel that o-phenyl phenol is not fungicidal as a
vapor. The two vapor applications described below may
depend more on the controlled environment in the chamber
than on the o-phenyl phenol for effectiveness.</p>
<p>Three variations on o-phenyl phenol application are
described below; two are vaporous and the third relies on a
combination of spraying and vapor. Before use, as much of
the visible mold as possible should be removed from the
bookbindings.</p>
<ul>
<li>for a few books, place them in an air-tight plastic bag
with o-phenyl phenol crystals. Do not allow the crystals to
directly touch the books. Seal the bag, and leave it for 4
to 6 weeks. Vapor from the slow sublimation of the crystals
should kill active mold.
<li>for use in an airtight chamber, mix o-phenyl phenol with
enough ethanol or trichloroethane to dissolve the crystals.
Use 2 tablespoons of o-phenyl phenol for each square foot of
the chamber. Seal the books inside with the o-phenyl
phenol, and leave them for three weeks. Again, o-phenyl
phenol vapor should kill the mold.
<li>for treating large outbreaks, use a solution of 13%
o-phenyl phenol in ethanol or 10% o-phenyl phenol in
trichloroethane. An experienced commercial exterminator
should be employed for implementation of this procedure.
The solution is sprayed into the air in the enclosed area
for several hours on each of three consecutive days (at a
minimum), or for 6 treatments spread out over nine days (the
former done at the Denver Public Library, the latter
recommended by Dr. Robert McComb at the Library of
Congress). Those persons who are spraying the o-phenyl
phenol solution must wear protective clothing, gloves, and
respirators. The entire building should be sealed and
inaccessible to unprotected persons during treatment.
Several hours after the final spraying, the windows should
be opened and fans turned on.
</ul>
<p>After all treatments, thoroughly aerate all materials.
Precaution should be taken against inhalation of the
o-phenyl phenol vapor. When sprayed, the o-phenyl phenol
will be effective for 30 to 40 days, and will slowly
evaporate during that time. The treated books should be
quarantined from the public during that period, and
otherwise handled only when wearing rubber gloves and a
respirator with an organic vapor cartridge.</p>
<p>Spraying individual books with o-phenyl phenol solutions
should only be done by a conservator with a fume hood. As
mentioned earlier, spraying of large collections in situ
should be done by qualified exterminators who have
experience with fumigation for mold. They are best equipped
to handle the spraying safely.</p>
<h5>III.B.2.c. Ethylene oxide</h5>
<p>Ethylene oxide is among the most effective of mold
fumigants for library materials. Because it is highly
flammable, ethylene oxide is mixed with Freon (8.8:1.2
ratio) or carbon dioxide (9:1 ratio) and then applied in a
vacuum chamber. The cycle is usually 12 hours long.
Ethylene oxide has been used as a fumigant in libraries,
archives, and museums since the early 1930s.</p>
<p>Ethylene oxide is also, however, extremely toxic and
carcinogenic; its use is regulated by the Occupational
Safety and Health Administration (OSHA). The permissible
exposure level for humans is one part per million (ppm), as
an 8 hour time-weighted average. This is a level that very
few of the vacuum chambers originally designed for ethylene
oxide use can maintain. Studies have shown that even as
many as 75 post-exposure air wash cycles still leave 4 ppm
of ethylene oxide in some chambers. Ethylene oxide has a
distinctive odor when present in the air in concentrations
greater than 300 ppm. There is also concern that some
materials, such as leather, retain ethylene oxide, which
will volatilize into the air for several months after
treatment.</p>
<p>Exposure to ethylene oxide irritates skin, eyes, and the
respiratory system. Exposure can also cause dizziness,
dullness, sinus congestion, vomiting, and nerve damage.
Ethylene oxide is linked to leukemia, stomach cancer, brain
cancer, and reproductive dysfunctions among men and women,
including genetic damage and spontaneous abortion.</p>
<p>Most libraries and archives which had installed ethylene
oxide fumigation chambers no longer use them. Some
commercial exterminators or sterilizers may have suitably
controllable chambers for use with ethylene oxide. However,
it is difficult to move moldy books for treatment, the
treatment is likely to be costly, post-treatment aeration is
lengthy, and those using ethylene oxide chambers for
sterilization may not be willing to treat books for mold.
So, despite its effectiveness, ethylene oxide is seldom
recommended or used any more for mold fumigation in
libraries and archives.</p>
<h5>III.B.2.d. Paradichlorobenzene</h5>
<p>Paradichlorobenzene is a mild fumigant. It comes in
crystalline form at room temperature, and should be used in
an enclosed space. It is not a proven fungicide, but seems
effective as a fungistat. Three weeks of exposure is needed
for the application to be effective; less time is needed if
the crystals are volatilized by heat, as were the thymol
crystals described above.</p>
<p>Paradichlorobenzene seems to be most useful as a method
for preventing mold growth, especially in small, enclosed
spaces. It is hazardous if inhaled, ingested, or in contact
with skin. Exposure can cause dizziness, headaches, skin
and eye irritation, respiratory problems, and loss of
coordination. Long-term effects include dermatitis and
possible liver and kidney damage.</p>
<h5>III.B.2.e. Carbon dioxide</h5>
<p>Carbon dioxide has been suggested by Richard Smith as a
possible fumigant. As far as I can tell, no experiments
have been undertaken to test its effectiveness. Carbon
dioxide is a high pressure gas which would have to be
carefully handled in a chamber. It is estimated that a
fumigation cycle would take several days. Because it has
not been practically demonstrated, carbon dioxide is not a
recommended fungicidal treatment for books.</p>
<h4>III.B.3. Miscellaneous Activities to be Carried out in
Conjunction with Treatment.</h4>
<h5>III.B.3.a. Cleaning Books and Paper.</h5>
<p>Use a clean dry rag or a soft-bristled brush to brush
mold from paper and books. Ethanol can be used to wipe away
visible mold on bindings. It should not be applied to paper
(texts) except by a conservator. Application should be done
carefully as ethanol may change or remove color from some
bindings. Visible mold can be wiped away before or after
treatment and, with a large infestation, it may be necessary
to do so at both times. When wiping off mold, be careful
not to brush it into the air indoors or onto other objects;
this can be accomplished by wiping books or papers off
outdoors or under a fume hood. Used rags should be stored
in sealed plastic bags until they can be washed in bleach
for re-use. Visible mold can also be removed by vacuuming
the books with a wet/dry vacuum cleaner. The tank should
contain a mold-killing solution, such as 10% sodium
hypochlorite in water. Remember to wear plastic or rubber
gloves and filtration masks when handling moldy
materials.</p>
<h5>III.B.3.b. Cleaning the Room(s).</h5>
<p>While books are being treated, the area in which they
were stored should be cleaned. Shelves, floors, walls,
ceilings, and windows can be cleaned with a mold and mildew
killing solution, such as Lysol, Clorox, or X-14. Make sure
that the area is properly ventilated while cleaning. Don't
return treated books to the area until it has been cleaned.
It may also be necessary, depending upon how serious the
infestation is, to clean carpets and drapery. Filters and
heat-exchange coils in HVAC systems should be checked and
replaced or cleaned with a mold-killing household
cleaner.</p>
<h5>III.B.3.c. Odor removal.</h5>
<p>Charcoal and/or baking soda can be used to remove the
odor of mold, if the treatment has not done so. Simply
place briquettes and/or bowls of baking soda in the area to
absorb the odor. Do not wipe the books or paper with the
charcoal or baking soda.</p>
<h5>III.B.3.d. Monitoring.</h5>
<p>Continue to monitor the area and the treated books and
papers after the fungicidal treatment has occurred. Changes
in the environment should have been made (either before or
during treatment) to reduce the possibility of future
outbreaks; i.e., humidity and temperature control
established, air circulation improved, leaks fixed or other
sources of moisture removed. Nonetheless, careful watch
should be kept over treated collections to prevent new
outbreaks. Books seem to be somewhat more susceptible to
mold after treatment.</p>
<h2>IV. Concluding Recommendations</h2>
<p>Most authorities agree that fumigating collections with
toxic chemicals is rarely necessary for dealing with mold
and mildew problems. Treating individual incoming items may
occasionally be necessary, but storing collections in
appropriate environmental conditions should prevent the need
for fumigation. To quote Dr. Thomas Parker, of Pest Control
Services, Inc.:</p>
<blockquote><p>fumigation will not control mold and
mildew if the library materials are placed back into the
same conditions from which they came. In most instances
library materials that have been fumigated are then
stored in areas which do not have an environment
conducive to mold growth. The success of the fumigation
is given as a reason for the control of the mold and
mildew, when in fact, the new area in which the
materials are stored is the governing factor as to why
mold and mildew is now being controlled.</p></blockquote>
<p>Maintenance of proper environmental conditions will
prevent mold growth. And if mold does occur, a relatively
gentle form of cleaning along with improving the environment
will solve the problem in most situations. I recommend that
you try the following before instigating chemical
treatment.</p>
<ol> <li>Determine the cause: check temperature and
relative humidity levels; check to see if the material has
been wet and, if so, why; check heat-exchange coils in air
conditioning units.
<li>Isolate materials: place individual items in sealed
plastic bags; quarantine stacks; for large and heavy
infestations, it may be necessary to restrict access to the
building/room.
<li>Modify the environment: readjust relative humidity to
the best of the HVAC system's ability; set up fans to keep
air circulating in the affected area; install portable
dehumidifiers in the affected area if the HVAC system cannot
be controlled; turn lights on in affected areas for as long
as possible during periods of obvious mold growth.
Continuously record temperature and relative humidity until
they stabilize at an acceptable level.
<li>Clean: wipe visible mold from books or papers with a
clean dry rag or a soft brush; bookbindings can be wiped
with ethanol or vacuumed with a wet/dry vacuum cleaner;
clean shelves, walls, floors, air conditioning heat-exchange
coils, air vents, etc. with Lysol, Chlorox, X-14, or other
mold-killing solutions; if you are dealing with a small
quantity of books, you can set them out in the sun to dry
out, otherwise use fans following the ethanol/vacuum
cleaning.
<li>Monitor: keep watch on the affected area for several
months beyond the mold outbreak and clean-up, even after the
environment has been restored to conditions which inhibit
mold growth.
</ol>
<p>Research and testing continue to assess the effectiveness
of fungicides, to determine appropriate treatment
procedures, and to identify molds and mildews and their
characteristics. Studies may result in changes to existing
procedures for mold control in the future. The SOLINET
Preservation Program is able to provide advice and
assistance in dealing with mold infestations in specific
situations. Please call if we can help.</p>
<h2>Bibliography of Sources Consulted For Information
Provided In This Leaflet</h2>
<p><cite>Abbey Newsletter</cite>, v. 7, no. 4 supplement (Sept.
1983). The entire issue is on fumigation.</p>
<p>Ballard, Mary W. and Norbert S. Baer. "Ethylene
Oxide Fumigation: Results and Risks." <cite>Restaurator,</cite> v. 7
(1986), p. 143-168.</p>
<p>Byers, Barry. "A Simple and Practical Fumigation
System." <cite>Abbey Newsletter</cite>, v. 7, no. 4 supplement
(Sept. 1983), p. 1-4. Includes description and
instructions for constructing a thymol chamber.</p>
<p>Center for Occupational Hazards, 5 Beekman St., New
York, NY 10038 (212-227-6220). Summaries available on
ethylene oxide standards, as well as safe handling
procedures for various other chemical fumigants
discussed in this paper.</p>
<p>Chamberlain, William R. "Fungus in the Library."
<cite>Library and Archival Security</cite>, v. 4, no. 4 (1985), p.
35-55. Describes mold outbreaks at the Virginia State
Library in 1978-1980.</p>
<p>Daniels, V. and B. Boyd. "The Yellowing of Thymol in
the Display of Prints." <cite>Studies in Conservation</cite>, v. 31
(1986), p. 156-158.</p>
<p>Dawson, John. "Preventive Measures: Fumigation."
In Proceedings of An Ounce of Prevention: A Symposium
on Disaster Contingency Planning ..., March 7-8, 1985.
Toronto, Ontario: Toronto Area Archivists Group, 1986,
p. 54-63. Available from the Toronto Area Archivists
Group, Education Foundation, P.O. Box 97, Station F,
Toronto, Ontario M4Y 2L4, Canada. Also available from
the Society of American Archivists.</p>
<p>"Gamma Radiation." <cite>Abbey Newsletter</cite>, v. 8, no. 2
(April 1984), p. 25, 28.</p>
<p>"Gamma Radiation Approval Seen." <cite>Abbey Newsletter</cite>,
v. 10, no. 1 (Feb. 1986), p. 12.</p>
<p>Gustafson, Dr. Ralph. Notes from a speech given 20
February 1987 at the South Carolina Library Association
meeting of the Archives and Special Collections
Roundtable, Columbia College, Columbia, South Carolina.
Dr. Gustafson is a mycologist in the Biology Department
at Winthrop College, and is working on a study of
fungicides for library and archival material under a
grant from the Council on Library Resources.</p>
<p>Haines, John H. and Stuart A. Kohler. "An Evaluation
of Ortho-Phenyl Phenol as a Fungicidal Fumigant for
Archives and Libraries." <cite>Journal of the American
Institute for Conservation</cite>, v. 25 (1986), p. 49-55.
Also, Mary-Lou Florian's letter to the editor in regard
to the Haines-Kohler article, in <cite>JAIC,</cite> v. 25 (1986), p.
109.</p>
<p>Hanus, Jozef. "Gamma Radiation for Use in Archives
and Libraries." <cite>Abbey Newsletter</cite>, v. 9, no. 2 (April
1985), p. 34.</p>
<p>Horáková, Hana and Frantisek Martinek. "Disinfection
of Archive Documents by Ionizing Radiation."
<cite>Restaurator,</cite> v. 6, no. 3-4 (1984), p. 205-216.</p>
<p>Kowalik, R. "Microbiodeterioration of Library
Materials." <cite>Restaurator,</cite> v. 4, no. 2 (1980), p. 99-114;
v. 4, no. 3-4 (1980), p. 135-219.</p>
<p>Kowalik, R. "Some Problems of Microbiological
Deterioration of Paper." Annali della Scuola Speciale
per Archivisti e Bibliotecari dell'Universita di Roma,
Nuova Tecnica Grafica, v. 9, no. 1-2 (1972), p
.61-80.</p>
<p>Lafontaine, Raymond H. Silica Gel. <cite>Technical
Bulletin</cite> number 10. Ottawa, Canada: Canadian
Conservation Institute, 1984.</p>
<p>McGiffin, Robert F., Jr. A Current Status Report on
Fumigation in Museums and Historical Agencies. Technical
Report 4. Nashville, TN: American Association for
State and Local History, 1985.</p>
<p>"More About Gamma Rays." <cite>Abbey Newsletter</cite>, v. 8, no.
4 (July 1984), p. 53-54.</p>
<p>Nagin, Deborah and Michael McCann. "Thymol and
O-Phenyl Phenol: Safe Work Practices." In
Ritzenthaler's <cite>Archives & Manuscripts: Conservation</cite>,
Appendix B (see below). Also available from the Center
for Occupational Hazards, at the address above.
Includes a description and instructions for construction
of a thymol chamber.</p>
<p>Nyuksha, Yu.P. "Biodeterioration and Biostability of
Library Materials." <cite>Restaurator,</cite> v. 4, no. 1 (1980), p.
71-77.</p>
<p>Occupational Safety and Health Administration.
"Occupational Exposure to Ethylene Oxide." <cite>Federal
Register</cite>, 22 June 1984, p. 25, 734-5, 809.</p>
<p>Parker, Thomas A. "Integrated Pest Management for
Libraries." Unpublished article, from a presentation
given at Osterreichische Nationalbibliotheck, Vienna,
Austria, for the First Conference on Preservation of
Library Materials, sponsored by the Conference of
Directors of National Libraries in cooperation with IFLA
and UNESCO, April 1986. Available from Dr. Parker at
Pest Control Services, Inc., 14 E. Stratford Ave.,
Lansdowne, PA 19050 (215-284-6249).</p>
<p>Preservation Office, Library of Congress. "Fact
Sheet on Mildew and Mold." Distributed by the National
Preservation Program Office, The Library of Congress,
Washington, D.C. 20540.</p>
<p>Raven, Peter H., Ray F. Evert, and Helena Curtis.
<cite>Biology of Plants</cite>, 2nd ed. New York: Worth Publishers,
1976.</p>
<p>Ritzenthaler, Mary Lynn. <cite>Archives and Manuscripts:
Conservation</cite>. Basic Manual Series. Chicago: Society of
American Archivists, 1983.</p>
<p>Roberts, Matt T. and Don Etherington. <cite>Bookbinding
and the Conservation of Books: A Dictionary of
Descriptive Terminology</cite>. Washington, D.C.: Library of
Congress, 1982.</p>
<p>Smith, Richard. "Fumigation Dilemma: More Overkill
or Common Sense?" <cite>New Library Scene</cite>, v. 3, no. 6 (Dec.
1984), p. 1, 5-6.</p>
<p>Thomson, Garry. <cite>The Museum Environment</cite>. 2nd ed.
London: Butterworths (in conjunction with IIC),
1986.</p>
<p>Turner, Sandra. "Mold ... the Silent Enemy." <cite>New
Library Scene</cite>, v. 4, no. 4 (Aug. 1985), p. 1, 6-8, 21.
Article on the Denver Public Library Administrative
Center mold outbreak in August 1984.</p>
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