Agents of Deterioration

AGENTS OF
DETERIORATION
Prepared By: Mr. JoloVan Clyde S. Abatayo, RL

Let’s define preservation again…
■ Preservation is the generic term, and includes all activities
associated with the maintenance of resources and the preservation of
information content.
■ This is in contrast with conservation, which refers to the physical
items themselves in order to extend their usable life (and restoration,
which refers to treating damaged material to bring to its near original
condition)

Causes of deterioration may be:
External causes are:
Physical
Chemical
Biological
improper storage
unauthorized exposure
risky handling
Theft
natural calamities.

Internal causes are :
poor quality of paper or materials used
the chemicals used for printing and binding.

Physical Agents
■ Temperature
■ Relative Humidity
■ Light
■ Sound (Vibration)
■ Magnetism

Physical Agents and their Preventive
Measures
■ Maintain constant temperature ( 22 –23 o C ) and Relative Humidity
(45 – 50%)
■ Proper ventilation should be maintained
■ Air-conditioning is the best solution
■ To control excess humidity install dehumidifiers, or placement of silica
gel in appropriate places.
■ Use sun filters, lead bulbs, acetate foils etc. to control the powerful
radiant light energy

■ The levels of light (should not exceed 50 Lux ) should be decided based
on the stack area and the user area
■ Handle carefully the documents in the library while transporting from
one floor to another
■ Avoid using mobile storage system which may create friction and
damage documents
■ Libraries should be located away from subways, trains, automobiles, etc.
to avoid the effect of vibration from outside sources
■ Stray magnetic fields are the natural enemy of magnetically recorded
information. Avoid using magnets, magnetic notice boards, etc.

Chemical Agents
■ Dust and Dirt
■ Internal Acidity of Paper and Ink
■ Air Pollution and Atmospheric Gases

Chemical Agents
■ Examples of pollutants are dust, smoke, coke dust, fly ash, salt particles,
calcium, ammonium sulphate, nitrates, chlorides, solid oxides, soot tars, and
gases like carbon monoxide, nitric oxide, nitrous oxide, Sulphur dioxide, ozone,
olefins, aromatic hydrocarbons, aldehydes, ketones, paraffin, hydrogen sulphide,
halogen compounds and ammonia.
■ All these factors lead to increase the acidity of the documents.
Deacidification methods can be used to remove the acid content
and increase the longevity of documents.
■ The Library of Congress estimates that deacidification can prolong
the life span of paper-based library materials by 250 to 300 years.

Biological Agents
■ Biological agents thrive on the organic matter they find in
library materials.
■ Absence of proper ventilation, darkness, high temperature
and relative humidity encourage their spread.
■ The biological agents can be grouped into macro
organisms and micro organisms.

Macro organisms
■ Silver fish
■ Book lice
■ Book worm
■ Cockroaches
■ White ants (Termites)
■ Rodents
■ Man

Chemical and Biological Agents and their
Preventive Measures
■ Deacidification is a process of treating paper documents for the
purpose of neutralizing acids within the paper and to create an alkaline
buffer.
■ Fumigation is a method of pest control that completely fills an area
with gaseous pesticides—or fumigants—to suffocate or poison the pests
within.

■ There are many pesticides like ( DDT ; Pyrethrum ; Para
dichloro benzene etc.) available in the market .
■ These pesticides may be sprayed periodically.
■ There are agencies specialized in this area that may be
consulted incase one has any specific problems.
■ The control of termites requires specialized attention in
libraries.
■ As termite infestation starts from the soil, creation of
chemical barrier around the building using crude creosote in
kerosene ( 1:1 ) or Dieldrex in water ( 1:60 ) is recommended.

■ Wooden structures are to be coated with creosote oil and
solignum.
■ Constant vigil against termite infestation is to be maintained.
■ Care should be taken that books and other documents on the
shelves are not directly sprayed upon.
■ Problem of rodents can be controlled by trapping, stomach
poisoning (zinc phosphide and arsenic oxide) and sealing of
crevices, cracks, and entry points.

■ Markings on the documents by pencil or pen by users and
using the book as a pillow for protecting their heads during
monsoon also contributes to the deterioration process of
documents.
■ It is a very difficult and delicate issue.
■ This can be prevented by educating the users and displaying
notices explaining the importance of books at prominent
places in the library.

Micro organisms
■ Fungus
■ Mildew and Mold

Materials Handling
■ Storage system
■ Exhibition
■ Transportation
■ Photocopying

Materials Handling
■ Libraries should have proper storage system depending upon
the type of documents such as books, periodicals, microfilms,
microfiches, CD-ROMs etc. and size of documents such as
maps, atlases, globes, etc.
■ When documents are removed for exhibition, care should be
taken to avoid direct exposure to ultraviolet radiation and
minimize the transportation. Indiscriminate photocopying
should be avoided.

Preventive measures forTheft and
Vandalism
■ Tag materials with magnetic strips. These strips will trigger
alarms if users try to carry the materials through electronic gates
at library exits without properly checking out the items at the
circulation desk
■ Install closed circuit TV to monitor the users movements
■ Use wire mesh to cover windows
■ Deploy security guards at the library entrance

Preventive measures for Fire
■ Install fire or smoke alarm system
■ Keep fire fighting equipments in designated places in the
library
■ Provide fire fighting training to all employees in the
library

Examples of Natural Disasters
■ Flood
■ Cyclone
■ Earthquakes

Natural Disasters:What to do?
■ It is very difficult to predict the natural disasters.
■ There should be a contingency plan which should form part of
the preservation policy aimed to minimize the loss and rescue
the materials to safer places when disasters strike.
■ For that it is vital to know which procedures to follow, to test
them and include them in periodic security exercises involving all
of the library staff.
■ An up-to-date address list must be kept indicating whom to call
in case of disaster (vital installations such as security, hospital,
fire fighting unit, etc.).

ENVIRONMENT
■ The environmental factors of temperature, humidity,
light, and atmospheric and particulate pollutants can
all cause degradation reactions.
■ The chemical, mechanical, and biological nature of
these reactions may vary for different materials.

Relative humidity (RH)
■ Relative humidity (RH) - It can be expressed as the
ratio (in percent) of vapor pressure in a sample of moist air
to the saturation vapor pressure at the same temperature.
■ It is a difficult concept to comprehend and therefore
warrants explanation.

■ If the water vapor in one cubic meter of air, at normal
atmospheric pressure, was extracted and weighed, the
absolute humidity of the sample of air would be known
and expressed as grams of water per cubic meter of air
(g/m³).
■ As air temperature increases, the amount of water vapor
air can hold increases as well.

■ At 10 °C (50 °F) air can hold no more than 9 grams of water
vapor.
■ The air is at its maximum absolute humidity and is said to be
saturated.
The relative humidity of the air in the container when only 9 grams
of water vapor was present would have been:
absolute humidity of sample air /absolute humidity of
saturated air = 9/17 = 0.53, or 53%

■ If the air were cooled to 9 °C (48 °F), it would become saturated
with water vapor, and the RH would rise to 100%.
■ If the air were cooled any further, droplets would form on the
side of the container because the air must give up some of its
moisture as condensation.
■ The temperature at which condensation first occurs (the
temperature at which the air reaches saturation) is called the
dew point.
■ Indoors, in winter, the room air circulates to window panes,
which are often cold enough to cool the air below its dew point.
■ Drops of water then appear on the windows.

Temperature and relative
humidity
The following statements need to be kept in mind whenever
temperature and relative humidity are an issue.
■ The first point that needs to be understood about temperature and
relative humidity is that there is no one ideal level for all types of
library material – only values and ranges that minimize specific
types of change in materials and objects. A temperature or humidity
that is acceptable for one object may be disastrous for another. For
example, photographic film, magnetic recordings, and digital carriers require
low storage temperatures and relative humidity levels if their longevity is to be
ensured; whereas parchment and vellum items require an RH higher than 50% if
they are to retain their flexibility.

■ There is extensive scientific evidence to suggest that paper will retain its
chemical stability and physical appearance for longer at a constant, low storage
temperature (below 10 °C / 50 °F) ) and relative humidity (30–40%).
■ However, while the paper text-block in a leather or vellum binding may
benefit from being kept at a low RH, the binding itself will inevitably
suffer. Leather and vellum need an RH of at least 50% if they are to
continue to operate mechanically.The argument of
chemical versus mechanical damage
or
content versus artefact
has to be carefully considered when deciding what temperature and
relative humidity ranges will have the most benefit for particular
collections

The effects of temperature
■ Chemical reactions increase in organic materials when
humidity and temperature rise.
■ While moisture can catalyze chemical reactions,
increases in temperature will accelerate the rate of
these reactions.

■ It has been frequently stated that for every 10 °C (18 °F) rise in
temperature, the rate of chemical degradation reactions in
traditional library and archive material, such as paper and books, is
doubled. Conversely for every 10 °C (18 °F) drop the rate is halved.
■ Heat coupled with low relative humidity will eventually lead to
desiccation and embrittlement of certain materials – leather,
parchment/vellum, paper, adhesives, the adhesive binders on audio
and video cassettes, etc.
■ Heat together with high relative humidity encourages mold growth
and creates an environment conducive to pests and insects.
■ Cold (less than 10 °C /50 °F) together with high relative humidity and
poor air circulation will lead to dampness and eventually mold
growth.

The effects of relative humidity
■ Organic matter
- is hygroscopic. It gains and loses water with increases and
decreases in RH.
■ Consequently, materials expand and contract as moisture
levels rise and fall.

■ An RH of 55–65% minimizes mechanical damage as materials
retain their flexibility.
■ A sustained RH above 65% can eventually cause adhesives in
both modern and traditional library material to soften and lose
their adhesive strength.
■ Above 70% RH, biological attack is a serious probability even if
temperatures are low. In areas of poor air circulation RH should
not exceed 60%; and even when air circulation is good RH
should not exceed 65% in order to avoid mold growth.
■ A low RH (less than 40%) minimizes chemical change but can
cause materials to shrink, stiffen, crack, and become brittle.

The effects of fluctuating temperature
and relative humidity
■ Severe fluctuations or ‘cycling’ of temperature and
relative humidity will cause more damage than
constantly high readings and so must be avoided.

■ As has been stated, if the water content of a room is fixed, a
sudden lowering of temperature will cause a rapid rise in the
relative humidity, leading to condensation and possibly
resulting in mold and other problems excess moisture causes.
■ Moderate changes over a long period of time produce minimal
stress in materials that are free to expand and contract.
Fluctuations of temperature and relative humidity affect the
dimensions and mechanical properties of organic materials and
can lead to damage if they occur over a short period of time.
■ Visible damage can take the form of flaking inks, warped covers
on books, and cracked emulsion on photographs.

Measuring and recording temperature
■ Environmental conditions in all areas should be adequately
monitored and recorded with reliable and regularly maintained
thermohygrographic or electronic recording equipment.
■ Monitoring is very important because it documents existing
environmental conditions; supports requests to install
environmental controls; and indicates whether any climate-
control equipment present is operating properly and producing
the desired conditions.

■ When monitoring equipment indicates notable
changes in environmental conditions, reports should
be given to authorities so that appropriate measures
are taken immediately.

Recommended levels of temperature
■ In general, library material should be stored and used in
stable conditions which are not too hot, not too dry, and not
too damp.
■ Many attempts have been made to provide ‘ideal’ figures for
temperature and relative humidity levels. However, it is now
recognized that it is probably impractical and unrealistic to
maintain a building or stack temperature at one setting
throughout the year, especially in areas with extreme
temperature variations, without incurring huge costs.

Recommended levels of temperature and
relative humidity
■ If temperatures do rise above 20 °C (72 °F) it is vital that relative
humidity levels do not rise or fall beyond acceptable levels.
■ In institutions, temperatures are often dictated by what is
deemed suitable for human comfort, around 20–22 °C (68–72
°F) for sedentary activities. Human beings are sensitive to
changes in temperature but relatively insensitive to changes in
humidity, while the opposite is true for most library material.

Setting relative humidity levels is always a
compromise and is largely influenced
by several factors:
■ the nature of the collections
■ local climatic conditions
■ resources available to control the environment.

Taking into account these factors the following
parameters should be observed:
■ a level of moisture high enough to maintain flexibility
■ a level low enough to slow deterioration of materials and
control insects and mold
■ a level that will do no structural harm to library buildings due to
condensation in cold weather.

The influence of local climatic conditions on
relative humidity
■ If the temperature in storage areas is considerably
lower than rooms where material is used, then it is
essential to allow the material to acclimatize in an
intermediary space to prevent any possibility of
condensation or distortion.

■ In humid parts of the world, where relative humidity does not
fall below 65% all year round and is much higher for long
periods, it is unrealistic to expect a level much below 65%,
unless the institution is air-conditioned day and night all the
year round at great cost. In these regions good air circulation is
imperative if mold is to be discouraged.
■ In arid areas, where RH rarely rises above 45%, maintaining a
level between 40–45% is all that can really be expected, unless
great expense is incurred. Once again the key is to avoid
fluctuations, to cool the air, and to keep certain materials like
parchment and leather in an area where RH can ideally be
maintained at no lower than 45%.

■ Temperate regions with warm summers and cold winters often
fare far worse than arid or humid areas.The RH in summer may
be acceptable, but in winter, when central heating is used, it is
often hot and dry during the day, and at night, if the heating
goes off, it becomes cold and damp. Such fluctuations do far
more damage than a constant high or low RH all the year
round.
■ In northern parts of America, Canada, and northeast Europe,
maintaining 50% RH in winter without condensation is
extremely difficult. Some institutions acclimatize their
collections seasonally by gradually reducing levels of RH
towards winter and increasing them towards summer.

Atmospheric and particulate pollution
■ Air pollution is to a large extent associated with towns and
industry and is an other cause of damage to paper and other
organic materials.Air pollutants vary greatly in nature, from
gases to particulates such as dirt and dust.

Gaseous pollutants
■ Gaseous pollution is caused overwhelmingly by the burning of fuels.
■ Pollutants such as sulphur dioxide, hydrogen sulphide, and
nitrogen dioxide combine with moisture in the air to form acids that
attack and damage library material.
■ Ozone is a powerful oxidant which severely damages all organic
materials. It is a product of the combination of sunlight and nitrogen
dioxide from automobile exhaust; it may also be produced by
electrostatic filtering systems used in some air conditioners, as well as
by electrostatic photocopy machines.

■ Smoking, cooking, and off-gassing from unstable materials
(cellulose nitrate film, paint finishes, fire-retardant coatings,
and adhesives) may also produce harmful gaseous pollutants.
■ Wood, particularly oak, birch and beech, emit acetic and
other acids, and vulcanized rubber releases volatile sulphides
that are especially damaging to photographs.
■ The composition of all equipment, materials, and finishes used
for the storage, transport, and display of objects should be
tested by recognized methods to ascertain whether they are
likely to produce harmful emissions.

Particulate pollutants
■ Particulate pollutants, such as soot, dirt, and dust abrade, and
soil disfigure materials.
■ Dust and dirt that have absorbed gaseous pollutants from the
air become sites for harmful chemical reactions when they
settle on library material.
■ Particulate pollutants can also aid mold growth.
■ Modern library material, such as magnetic and optical media,
are very sensitive to dust and dirt.

■ Dust is commonly a mixture of fragments of human skin, minute
particles of mineral or plant material, textile fibers, industrial smoke,
grease from fingerprints, and other organic and inorganic materials.
■ There are often salts such as sodium chloride (carried in from sea
spray or on skin fragments) and sharp gritty silica crystals.
■ In this chemical mixture are the spores of countless molds, fungi,
and micro-organisms which live on the organic material in the dust
(fingerprints, for example, serve as good culture media).
■ Much of the dirt is hygroscopic (water attracting), and this
tendency can encourage the growth of molds, as well as increase
the corrosiveness of salts, hydrolysis, and the release of acids.

Light
■ Light is energy and energy is required for chemical reactions to take
place.
■ All wavelengths of light – visible, infrared, and ultraviolet (UV) –
promote the chemical decomposition of organic materials through
oxidation.
■ Higher-energy ultraviolet is the most harmful.

■ However, light in all its forms, especially in the
presence of atmospheric pollutants, leads to a
weakening and embrittlement of cellulose, adhesives,
cloth, and skin materials.
■ Light can cause some papers to bleach and others to yellow
or darken; it can also cause media and dyes to fade or
change color, altering the legibility and appearance of
documents, photographs, art works, and bindings.

The following factors concerning light should be
known by all those responsible for preserving library
material:
■ Chemical reactions initiated by exposure to light continue even after
the light source is removed and materials are put into dark storage.
■ Light damage is irreversible.
■ The effect of light is cumulative.
■ The same amount of damage will result from exposure to a strong
light for a short time as to a weak light for a long time. 100 lux (the
unit of measure of illuminance) on a picture for 5 hours gives it an
exposure of 500 lux-hours, equivalent to 50 lux for 10 hours.

■ Visible and infrared light sources, such as the sun and
incandescent light bulbs, generate heat. An increase in
temperature accelerates chemical reactions and affects
relative humidity.
■ Daylight has the highest proportion of UV radiation and
therefore must be filtered.

Types of lighting
■ Incandescent lamps are the most familiar type of electric
light source. Light is produced by passing an electric current
through a thin tungsten wire filament.
- Incandescent lamps usually have less harmful UV radiation
output than fluorescent lighting, but they generate more heat
through infrared radiation. Tungsten incandescent lights also
burn less efficiently and must be replaced more often than
fluorescent lights.

Types of lighting
■ Fluorescent lamps are low-pressure mercury discharge
lamps which produce UV radiation which in turn excites a
phosphor coating that emits visible light.
-The use of different phosphors is responsible for the
various color characteristics these lamps exhibit.Although
fluorescent lighting is high in ultraviolet content, it is
usually installed in libraries because it generates less heat
and is more economical to operate.

Measuring light and UV levels
■ It is necessary to measure and record light and UV levels at
different times of the
year, as readings will change with the seasons.
■ A light meter or lux meter measures the intensity of visible light
in lux (lumens per square meter).
■ A camera with a built-in light meter can also be used to
measure light levels indirectly.
■ A UV meter measures the amount of UV radiation (wavelengths less
than 400 nanometers) in units of microwatts of UV radiation per
lumen.

Recommended light levels
■ Lighting in museums, galleries, and exhibition rooms is usually left to
specialists.
■ This should also be the case for library reading rooms and storage
areas.
■ While 200–300 lux are acceptable levels for reading rooms, attaining
such levels with a combination of natural and artificial light, which
satisfy staff and researchers, is difficult.

Recommended light levels
■ In stack and storage areas 50–200 lux is sufficient.
■ However, to achieve these levels it would be necessary to exclude all
natural light and rely entirely on artificial lighting.
■ Light sources with ultraviolet radiation emissions above 75
microwatts per lumen require filtering.

Light levels for material on
display
■ In exhibition situations, the light level falling on the surface of objects
on display must be kept low.
■ No more than 50–70 lux during an eight-hour day for a maximum of
60–90 days, is often recommended for light-sensitive materials like
colored paper, newsprint, and certain bindings (e.g. textile bindings),
and media like manuscript ink and watercolors.

Mold
■ The spores of fungi that become mold are always present in
the air and on objects and will grow wherever conditions are
favorable.
■ In general, moisture (above 65% RH), darkness, and poor air
circulation are ideal conditions.
■ Warmth is a factor, but certain molds and bacteria will thrive in
cold temperatures too (think of what can happen in a
refrigerator).

■ Mold can weaken, stain, and disfigure paper and
photographic material.
■ It is generally recognized that ‘foxing’ may be
attributable to mold reacting with trace elements in
paper.
■ Cloth, leather, vellum, and certain adhesives are also
affected by mold.

Attending to an infestation
■ Mold can be checked to see whether it is active or inactive.
Generally, active mold is damp, slimy, and smears if touched.
Inactive mold is dry and powdery and can be brushed off with a
soft brush.
■ If mold is discovered in large portions of a collection, isolate the
area immediately and do not attempt to clean up without first
consulting a mycologist to determine if toxic molds are present.
Certain molds commonly found in libraries can pose serious
health risks, causing headaches, nausea, eye and skin irritation,
and respiratory problems.

■ A conservator may have to be employed or at least consulted
on the treatment of infested items and on the return of the
affected area to a suitable condition for housing material.
■ If only a few items are affected, place them in a dry paper-
based box until treatment. If possible, include a desiccant,
such as conditioned silica gel packets.This enclosure will
prevent spores from circulating, but will not encourage the
growth potentially created by the tightly sealed microclimate
of a plastic bag.
■ Alternatively, move the affected material to a clean area with
relative humidity below 45%, separate from the rest of the
collection, and allow them to dry.

■ If immediate drying is not possible, or if many objects
are wet, freeze them; later they can be thawed, dried,
and cleaned in small batches. Material may also be
freeze-dried and then cleaned.
■ When dry, the items should be cleaned and stored
under suitable environmental conditions.The storage
environment is critical since even after cleaning, fungal
residue will be present.

Cleaning infested material
■ If the outbreak is small, and equipment limited, take the items
outside – well away from the building – on a calm, mild day and
brush them off with a soft white brush, away from you and
downwind.
■ Remove mold only with a vacuum cleaner that contains a HEPA
(high efficiency particulate air) filter capable of retaining 99.97%
of all particles down to 0.3 microns. Conventional vacuum
cleaners have drawbacks: often the suction is too strong; as the
bag fills up the efficiency decreases; the exhaust can be
contaminated with fine particles not trapped by the bag,
therefore redistributing them around the room.

■ An HEPA vacuum cleaner is an effective way to remove mold
because it does not spread the spores around.
■ Vacuum cleaners are designed to filter air through water are
unsuitable for capturing mold's small particles.
■ Even if a fungicide is present in the water, this will not prevent
particles of mold from being discharged back into the air.

■ While certain treatments can kill mold that is active, they are far
less effective with dormant spores, which are protected by
relatively impervious cell walls.
■ Proper conditions will insure that dormant fungi remain inactive
and will prevent germination of accidentally introduced active
spores.
■ If the environment is favorable to fungal activity, mold will grow.
■ Even if complete eradication were possible, it would not be a
permanent solution in storage spaces without climate controls.
■ More spores are always being introduced and would sooner or
later become a problem.

■ If it is not possible to remove mold outdoors, work in front of a
fan, with the fan blowing contaminated air out a window, or
work in a ventilation hood.
■ Make sure the ventilation hood uses a filter that traps mold. Be
sure to remove the mold in an area well away from collection
storage and other people.
■ Close off the room.
■ If the building has central/mechanical air circulation, block the
uptake vents so that spores are not spread through the
building via the air handling system.
■ Take care when disposing of solid cleaning materials such as
vacuum cleaner bags or filters.

■ These should be sealed in plastic bags and removed from the
building.
■ To remove inactive mold from paper or books, use a multiple-
filter vacuum cleaner (see above). Small brushes and nozzles
used for cleaning computers are useful for this purpose.
■ Papers can be vacuum cleaned through a plastic screen held
down with weights.A brush attachment should be used for
books.
■ Covering the nozzle or brush with cheesecloth or screening will
guard against loss of detached pieces.
■ Remember active mold is soft and subject to smearing, and is
easily rubbed into porous materials such as paper or cloth.

■ Active mold is best removed from valuable artifacts with a
small low-pressure vacuum cleaner.
■ This delicate work is best done by a conservator.
■ When fungal growth is visible on art objects or valuable items,
it should be removed by a conservator.
■ Staining caused by mold can often be removed or at least
lightened.
■ This is an expensive procedure and therefore most suitable for
objects of significant value.

Treating an infested area
■ It is important to find out what caused the mold outbreak in the
first place.
■ The room where a mold outbreak occurs must be dried and
thoroughly cleaned before the affected material can be
returned to it. For moderate to large mold outbreaks contact a
professional service that provides dehumidification or cleaning
of the premises.

■ If the RH is above 55%, it must be lowered before the collection
is returned to the area.Adjusting the HVAC system or adding a
portable dehumidifier may be all that is necessary. Also check
for leaks or water condensation on outside walls. Inspect the
heat-exchange coils in the heating/air-conditioning system, a
notorious breeding ground for fungi, and clean them with a
household disinfectant.
■ Vacuum clean the shelves and floor with an HEPA vacuum
cleaner, then clean them with a household disinfectant. Before
returning the cleaned material to the area, monitor the RH for
several weeks to make certain it does not exceed 55%.
■ After the items are returned, check daily for new mold
outbreaks.

Ways on How to Prevent mold
outbreaks■ Check new collections or shipments for the presence of mold.
■ Maintain moderate temperature and relative humidity (below 20 °C /
68 °F and 65% RH).
■ Circulate air.
■ Vacuum clean regularly.
■ Do not shelve books directly against an outside wall. Owing 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.

Ways on How to Prevent mold outbreaks
■ Do not allow plants into the building.
■ Waterproof basements and walls below ground level.
■ Place or adjust outside gutters and drains so that water does not
collect near the outside walls. Check gutters and drains regularly to
avoid obstructions.
■ Place lawn sprinkler systems so that they do not soak outside walls.
■ Regularly inspect collections for mold so that any infestation is
detected before it becomes serious.

Insects and pests
Insects which most commonly cause damage in libraries and
archives throughout
the world are:
Cockroaches
Silverfish
book-lice
beetles
termites.

■ They feed on organic substances such as: paper, pastes,
glues, gelatin sizing, leather, and book cloth; birds nests are
also a major source of food for insects, and bird droppings are
corrosive.
■ They prefer warm, dark, damp, dirty, and poorly ventilated
conditions.
■ Their damage is usually irreversible – text and images lost by
insects eating and boring through paper and photographs
cannot be replaced.
■ Termites can devastate buildings and collections.

Pests
Rodents such as rats and mice can devastate collections:
■ They will destroy books in order to obtain paper for their nests.
■ They can cause fires by gnawing through electrical insulation.
■ They will pare their teeth on library furniture and fittings.
■ Their droppings are corrosive and can leave permanent stains.

Treating infested material
■ Always look for the least toxic alternative.
■ For example, when faced with a box of books with silverfish,
avoid chemical treatments and simply hand-clean the volumes
using a vacuum cleaner and a soft brush.
■ When uncertain if pests are active, clean the item, bag it, and
examine it later for signs of fresh activity.
■ Be sure to segregate collections from new accessions or items
with possible pest problems.

The least toxic approach is not only the environmentally friendly
approach, but for many collections it is the only responsible
approach:
■ Most fumigants will likely affect the long-term preservation of at
least some materials.
■ There is no one fumigant which is known to be safe for all
collections.
■ Collections may be damaged through contact with the water- or
oil-based spray.
■ Fumigation offers collections no resistance to future pest attack.

■ It is essential that after treatment, steps are taken to prevent any
new infestation from being introduced.
■ This will probably mean segregating new (and possibly infested)
collections, strictly isolating collections with any signs of pest
activity, cleaning, and improving storage conditions.
■ Some institutions have selected freezing as an alternative to
chemical fumigation.
■ By rapidly lowering the temperature to at least –35 °C and
holding it at this level for up to several days, most life stages of
most insects can be killed.
■ While some commercial freezers are adequate for pest control,
others are not able to lower the temperature quickly enough.

■ A slow reduction in the temperature allows some
insects to go into a state resembling ‘suspended
animation’ and survive the treatment.
■ Naturally, it is also important to ensure that the
objects are not damaged by the low temperatures and
that condensation is controlled.

Preventing insect and pest infestations
It is now accepted that an integrated pest management (IPM)
approach should form part of every preservation program. IPM
involves:
Monitoring the building regularly for the presence of insects
and pests
Ensuring all staff, from cleaners to librarians, are vigilant and
report any signs of fresh damage and activity
Checking all material which is to be accessioned before it
enters the library

Using sticky traps. Traps have the advantage of catching insects before
they can be found visually; they catch a wide range of species; they can
be placed in areas which are difficult to inspect; trapped insects can be
identified and counted; traps are good indicators of an increase in insect
numbers in one area; they also highlight any failure of control treatment
Understanding the biology and life cycles of insects and pests, which
helps to know when and where they are likely to breed, what they are
likely to eat, where they are likely to live
Eliminating or containing all sources of likely infestation – ideally food
and drink should not be consumed on the premises; flowers and plants
should not be allowed in the building

■ maintaining an environment not conducive to pests and insects, which
is clean, cool, dry, and well-ventilated
■ preventing pests and insects from entering the building – making sure
doors close properly, installing mesh screens for windows and doors,
etc.
■ using appropriate exterior lighting, such as sodium vapor, which is
less attractive to insects
■ implementing a cleaning and hygiene program – rubbish should be
safely and properly disposed of; attics and basements regularly
checked and cleaned.

Improving the environment
■ If the objective is to retain a collection or specific individual
items indefinitely, then very close attention needs to be paid to
the environment in which the items are stored.
■ The ideal environment includes controlled temperature and
relative humidity, clean air with good circulation, controlled
light sources, and freedom from biological infestation.
■ Good housekeeping practices, security controls, and measures
to protect collections against fire, water, and other hazards
complete the range of environmental concerns.

■ Library buildings should be designed as far as possible to meet
preservation requirements.
■ These requirements affect many aspects of planning: design
and orientation of buildings; building materials (which can,
under some circumstances, be used to produce satisfactory
internal climatic conditions in preference to mechanical air
control systems); internal building and furbishing materials; and
materials used for furniture, including shelving as well as
lighting, both natural and artificial.

■ Indigenous and traditional building methods and materials in
subtropical and tropical areas often provide better storage
conditions for library material than those that are imported.
■ It is always worth considering constructing a sealed area within
a building for material which needs tight temperature and
relative humidity control.

Practical measures to improve the environment
In many places heating, ventilating, and air conditioning systems
(HVAC) may be too costly to install and maintain or may have to be
restricted to specific collections.
Nevertheless, there are many rudimentary measures and precautions
that can improve a library’s environment and protect collections.
A first step in all efforts to improve the environment should be sealing
the structure.
This step alone will improve the physical condition of the building by
reducing air infiltration, pest access, heating loss or heat gain, and air
and particulate pollution.

Making the building watertight will also reduce the sources of
moisture within the structure and may significantly reduce relative
humidity levels.
Use draft excluders and weather-stripping to make the building
weathertight.
Ensure windows and doors fit securely.
Ensure good air circulation by appropriate use of fans and windows.
Use dehumidifiers and humidifiers to reduce or increase relative
humidity.
Use insulation methods to reduce heat gain or loss.

Use UV-filters on windows and fluorescent lighting.
Use screens, blinds, shutters (preferably outside the windows, as this
reduces solar heat gain), and heavy curtains to keep out direct sunlight.
Ensure storage facilities are dark.
Ensure buildings are properly maintained to keep out dampness during
rainy periods.
Paint the outside of the building with a pale-colored light-reflecting
paint in hot climates.

Use close-fitting enclosures (boxes and envelopes) wherever possible to
protect important and valuable library material. These can create a
microclimate around the object, which delays the effects of changes in
temperature and relative humidity. They also shield the item from light,
and can act as a buffer against atmospheric pollutants and prevent
particulate deposits.
Be aware that while trees and vegetation near buildings can reduce heat
gain, they can also encourage insect and pest activity.
Locate plumbing and heating pipes outside storage areas.
Locate sanitary premises and sinks outside storage areas.

HVAC systems
■ If the institution has a heating, ventilation, and air conditioning
(HVAC) plant, then the following questions should be answered as
part of any environmental survey:
o Does the air conditioning provide constant climate control throughout the
year?
o Is the air conditioning system kept at a constant level 24 hours a day?
o Is the air conditioning turned down or shut off at any time?
o At what temperature and humidity levels is the air conditioning set?
o Are monitoring devices for temperature and RH regularly used in the facility?

HVAC systems
o If there is no air conditioning system or, areas not covered by the
system, how are rooms heated and/or cooled?
o If there is no air conditioning system or, areas not covered by the
system, how is humidity controlled?
o What sort of air filtration system is used?
o To what standard does it operate?
o Who maintains the air conditioning systems and how often?

Housekeeping
■ Housekeeping- It is done to ensure the protection of the collections
against particulate pollutants.
■ A regular and sustained program of cleaning should be
maintained, undertaken with care and under supervision.
■ Clean surroundings also discourage fungi, insects, and pests.
■ The cleaning program should include the examination of
collections not only to provide early warning of biological or
chemical damage but also to observe conditions throughout
the area.

■ Cleaning the floors of storage accommodation and book stacks
may be left to non-specialized staff under instructions to
respect the collections and not to touch library material or
shelves.
■ Directions should be given to retrieve pieces of bindings, record
slips, etc., from the floor (noting where they were found).
■ Library material on the shelves should only be cleaned by
properly trained members of staff.

■ It is important to provide appropriate materials and
equipment which remove rather than redistribute dirt and
dust.
■ Cleaning cloths to which particulates adhere rather than
dusters which merely spread them around in different
places should be used to clean library fittings.
■ Floors should be vacuum cleaned (not swept) and damp-
mopped once a week.
■ Cleaning agents must be nontoxic and pose no threat to
the collections from solvent fumes or abrasives.
■ Products containing oil, chlorine, alum, peroxides, and
ammonia should be avoided.

Agents of Deterioration

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