The Preservation Handbook Online

Table of Contents

I. Preservation
II. Assessment
III. Collection Assessment
IV. Agents of Deterioration
V. Monitoring collections
VI. Materials
VII. Storage
VIII. Conservation
IX. Disaster Planning
X. Housekeeping
XI. Resources / Suppliers
XII. Preservation Grants

Ideally storage should have...

-climate control
-monitors for RH, temperature, fire and theft
-each item accessioned with finding aid for accessibility.

Planning considerations will include...

-nature of the collection
-spatial requirements calculated from finding aids
-how the collection is to be used

Ideally storage should be in a...
- central space
- away from outside walls
- heating units
- plants
- water mains
- daylight

General Guidelines

* The ideal temperature for most products is 68°F +/- 2°F
* The ideal relative humidity level for most products is 50% +/- 5%
* Long-term storage should remain between 50°F - 55°F

* Damage to organic material begins to occur at 45% RH or less.
* Mold will flourish at 70% RH.

Climate must remain constant, large fluctuations are most damaging.

* "buffered" - smooth white crisp paper, pH is alkaline or greater than 7
* "unbuffered" - soft fibrous paper, pH is neutral = 7

Areas in red
indicate the highest priority for reducing potential deterioration to that format.
Areas in green
indicate dangerous conditions to avoid.


Biological Threats
Long -Term Storage
Exhibition / Loan

B&W Photos
Absence of reactive pollutants in atmosphere a necessity.

Salted paper prints




Encased Photos


Below 24° is ideal.

-Never to exceed 32°

-Fluctuations of more than 4° must be avoided.

30% is ideal

- Never to exceed 50%

Well-processed silver-gelatin images are stable to light.

-Resin coated papers are susceptible to light damage. Not to exceed 75 micro-lumens
Corrosive pollutants in atmosphere and moisture. Acid- free; lignin-free window mat enclosure with Mylar –D or cellulose triacetate sleeves.

Buffered tissue

Framed photo’s should have acid-free object boxes built of rag board, or acid-free cardboard
Dry cool dark storage. Levels higher than 50% RH are not acceptable. Movements between storage and exhibition should be done gradually. Handle with cotton gloves.
Color Photos
Unstable in both light and dark storage.

-Cold storage vault

-Below freezing point

25% is ideal

Fluctuations of no more than 5%

Prolonged exposure to light should be avoided.

- Light intensity should not exceed 50 lux.
Organic emulsion and dye components will attract silverfish and firebrats. Should be stored in chemically inert plastic sleeves made of either cellulose triacetate or polyester (Mylar-D), un-buffered paper envelopes, and handled as little as possible.

No buffered papers.
Humidity controlled cold storage. Each 10° reduction in temperature will double the life of color material. Signs of chromogenic dye loss or staining should be met with migration to preservation photocopy and restricted use of original. Temperature and electromagnetic –radiation are catalysts for deterioration. Color photos should not be used for exhibition or loan. If necessary for long-term display, photos should be migrated to Fuji-inax Ceramic color photographs.
Video Tape
Polyester base cassette tapes, no less than 1.5 mil thickness. No longer than 2 hours in length recorded at fastest speed
60-65°F ideal

25-45% RH

- Low humidity can create static.

No long-term exposure to ultraviolet or natural light. Dust, abrasive pollutants in atmosphere, electrical conduit, binders and mold growth, magnetic fields. Tapes should be stored in Inert polypropylene or polyethylene cases. Stored vertically in an upright position. Duplicate tape should be stored in off-site location. Rewound once a year.
No magnetic bookends. No motorized shelves

Use should be limited to research and not for exhibit.

-Color copies should be made of high use issues. Digital transference is another possibility to increase access and decrease use.

-Stock certificates
-Sheet Music
-architectural drawings
(Lower the temperature the better)
35-60% RH Limit exposure to UV and natural light

Silverfish, firebrats, psocids,

Mylar encapsulation
Acid Free-Lignin Free, Un-buffered paper folders
Stored in acid-free corrugated document boxes- Viewing areas should have UV filters in place

(Lower the temperature the better)
35-50% RH Limit exposure to UV and natural light Silverfish, firebrats, psocids, Cockroaches, rodents, book lice, book worms Acid free Buffered four-fold manuscript and book enclosures made from rag mat or blotter board and secured with cotton twill tape.
Glassine or buffered tissue can be used for interleaving.
Should be stored vertically on acidic barrier such as polyethylene sheeting with ethafoam, rag board or buffered papers. Dust covers of cotton, Tyvek (E) or polyethylene sheeting should be used. Viewing areas should have UV filters in place
Government Documents 60-65°F
(Lower the temperature the better)
35-50% RH Limit exposure to UV and natural light Silverfish, firebrats, psocids, Cockroaches, rodents Acid free buffered files and acid-free corrugated storage boxes 12x 15 x10 Possible candidate for online or microfilm consortium with other repository to increase access and scope of collection Viewing areas should have UV filters in place

- ivory

Temperature should not exceed 72°F.

40-50% RH

high RH and pollutants can affect salt migration in glass and ceramics without glazing.

-low RH cracking of ivory and some plastic

Ultra violet and natural light exposure detrimental to silk.
-Fluctuation in ambient conditions accelerate the hardening inherent to rubber.

Corrosive gasses lead to salt migration

-oxygen turns rubber hard

Glass, plastic, - buffered

Leather, rubber, metal
- unbuffered

High density foam can be used to make object nests
Oversized artifacts should be stored on rolled folder made of polyester film and acid-free, lignin-free tubes or in flat drawers.

Loose objects should be secured.

Objects should fit snugly in storage boxes.
Each item should be assessed for display needs. When there is a mixture of media, the dominant ones to consider are leather, cellulose, and plastic.
Textiles / Fabrics 55°- 68°F

°-20° C)
40-50% RH

Mold growth occurs readily on textiles
Light exposure will damage reactive dyes.

- Silks should never be exposed to ultraviolet radiation.
Corrosive gasses,

moths, Silverfish, firebrats, psocids, Cockroaches, rodents,


Interleaf textiles with appropriate tissue.

- Acid-free, unbuffered tissue should be used with: metallic thread, sequins, wool and silk.

-Acid-free, buffered issue should be used with: cotton, linen, rayon, and jute.

Wrap in mylar or unbleached muslim to protect from dust and handling. Tie with cotton twill.


Role on 1.25", 2", or 4" diameter archival tubes made of acid-free chemical pulp, buffered to a pH of 8.4, and bonded with chemically inert adhesive.

Length should be the waft dimension plus 2"

Store in acid-free storage boxes made from same material as tubes.


(B&W and color negatives should be stored separately.

acetate negatives

nitrate based film

paper negatives

Glass plate

Below 24°C

Never to exceed 32°C
30-35% RH Prolonged exposure to light will cause embrittlement to gelatin layer. Corrosive pollutants in atmosphere

-mold -chemical reactivity

Should be separated from prints

-dark Storage

-enclosures made of chemically inert uncoated polyester and

-paper sleeves -Acid-free tissue-
Un-buffered- for color negatives-
Buffered- for B&W



Not intended for display- Should be handled with cotton gloves.

-used to make positives.

- plant
-natural product
(dye,oil, resin, wax)
-nonmetals (ceramics, glass, clay, stone, mineral)
-bones, shells


(Lower the temperature the better)

Susceptible to extremes or fluctuating temperature

Ideal Rh 50%

Fluctuations of no more than 5%

-Susceptible to extremes or fluctuating RH

-Embrittlement will begin when RH drops below 45%.
-Mold growth will begin when RH is above 68%

Prolonged light exposure will increase fading in light-reactive dyes, and will catalyze chemical reactions

Moths, Silverfish, firebrats, psocids, Cockroaches, rodents, corrosive gasses, salt migration,

-Composite objects have an increased risk of deterioration

-Object boxes made of appropriate acid-free material should be constructed

wrap with appropriate tissue:
wood, bark, leaf fibers, straw, shell, beeswax -buffered

feathers, fur, leather,silk, metal, wool -unbuffered

- Separating reactive materials is necessary

Cool dark storage; continuous environmental control

- Build object nests to provide adequate support for materials
- Use coated metal shelving to promote air circulation when necessary
Limited display in UV controlled areas.
- Micro climates allow better control over mixed material collections. -Movements between storage and exhibition should be done gradually. -Handle with cotton gloves


65° - 70° F

Susceptible to extremes or fluctuating temperature.

40% - 55% RH.

Susceptible to extremes or fluctuating RH
Limit exposure to UV and natural light.

storage should remain dark
Corrosive pollutants in atmosphere

-composite objects have an increased risk of deterioration

Acid-free backing board screwed to the verso of the stretcher bar or frame

stable - vertically.

bad condition - horizontally

Each painting should be evaluated for exhibition


XXXXVIII Hahn, J. (1999) Yard and Garden: Entymology.Minnesota: University of Minnesota. Accessed
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