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


Paper - history

Paper was invented by the Chinese prior to the second century A.D. The earliest forms of paper were made from the mixture of bark and hemp. Through experimentation other fibers were added to make smoother, more flexible writing surfaces. "For six hundred years, the art of making paper remained an exclusively Far Eastern enterprise - until the jealously guarded secret of it's making fell into the hands of the Persians, who conquered the Chinese in A.D. 751 and established, in fabled Samarkand, the first paper mill built outside of China." xxx The Middle East brought the skills of paper making to the Mediterranean countries and then on to Europe. Following the invention of moveable type paper became the dominant writing surface.

Paper - composition

Paper is a felted surface made from the pulp of vegetable, mineral, or synthetic fibers. Paper can be made by hand or machine and serves many different purposes in our modern world. Whether hand or machine manufactured, the paper making process intertwines fibres deposited evenly on a porous surface by the action of water. The nature of paper is dependent upon both its methods of manufacture and the chemistry of the base fibers.

The building block of paper, cellulose, is composed of long polymer chains of carbon, hydrogen and oxygen. The intertwining polymers have great strength and flexibility, but are also hygroscopic. This means they absorb and release moisture to maintain equilibrium.

Paper - creation

Fibers are collected, cleaned, cooked, macerated and suspended in water. Pulp is lifted from water on a porous screen allowing water to drain away. The screen is called a mold and will vary depending on paper origin. Molds can be used as a way to identify certain paper's history. Automated machines have moving screens that replace the individual mold. The newly formed sheets are then transferred to felts or damp paper. In Western practice layers of felt or damp paper are placed on both sides of the sheet to form a "post." The post is used to absorb excess moisture from the new sheet when pressed. Eastern practice uses flexible molds that can be rolled off of the paper. Sizing is used to make paper water resistant and smooth. Other finishes include burnishing or calendaring, glazing, and coating for special purposes like photography.

Paper- inherent vice

Cellulose itself is neutral and stable, but upon contact with acidic elements the polymer chain begins to breakdown. Internal threats to paper come from: poor-quality pulp; bleaching residues; and unstable sizing. The lignin in wood based pulp is acidic and chemically unstable leading to the breakdown of surrounding cellulose fibers. Bleaching agents are manufactured with chlorine, a highly reactive chemical that forms hydrochloric acid. Bleaching residues left in the paper will degrade cellulose structure. Alum is used to evenly distribute sizing on papers surface and can produce sulphuric acid. The presence of any of these inherent factors will compromise paper longevity.

Paper - external threats

Accelerated acid migration occurs because of the hygroscopic qualities of cellulose. Contact with acidic materials, air borne pollutants or unstable pigments facilitate the production of sulfuric acid in cellulose and leads to paper embrittlement. Temperature and light acts as a catalyst for chemical reactions and artificially ages paper. Increased and fluctuating temperatures are harmful to paper substrates. Light exposure will discolor paper as well as light sensitive media. Exposure to fluctuating or high levels - above 68% - of relative humidity leave paper objects at risk to mold infestation and structural changes like buckling. Improper handling is perhaps the easiest threat to control. Improper storage, framing, and unsafe exhibit practices are the greatest threats to the preservation of paper objects. Disaster preparedness will help minimize collection damage in the event of small mishaps such as broken pipes or large problems like flooding or fire.

Paper - identification

Transparent light will reveal tell tale signs of handmade paper. Light and dark areas will be evident from the uneven distribution of pulp in the paper making process. Irregularities in color, type of fiber, or water droplets - rings on the paper- also indicates hand crafting. Paper origins can be identified by watermarks and laid lines. Laid lines are components of the mold or screen used to create the paper. Screens will have different distances between the wire mesh, giving them unique fibrous patterns. Wove paper was invented by James Wattman the elder around 1755 and has bee the usual paper for book printing since the early 19th century. Wove paper lacks chain or laid lines.

Paper - conservation concerns

Signs and symptoms of paper deterioration indicate consequences of inherent vice, high or fluctuating humidity, light exposure, temperate conditions, or poor handling. Determining the source of deterioration will help to quickly stabilize the object and correct any environmental or storage factors.

Acid migration - structural damage or discoloration from contact with acidic or reactive materials: generalized dark brown discolorization; loss of flexibility; mat burn; light staining; discoloration where acidic mat contacts paper; tape stains from improper repair or mounting; adhesive stains that seep from attachment points.

Biodeterioration - damage caused by insects, rodents or mold as a result of unsafe environmental conditions, lack of air circulation, or cleanliness: foxing: red/brown irregular spots; mold growth or fibrous clusters in various colors or overall haziness; insect damage: small holes, loss of certain color areas; raised dark brown specks.

Physical damage - structural weakness or disfigurement of paper from improper handling, incompatible materials, and fluctuations in temperature or relative humidity: overall cockling (buckling) is caused by extreme fluctuation in relative humidity; isolated cockling (buckling) is caused by improper mounting or incompatible materials; cracked book spines; rust stains from paperclips and staples; persistent curling indicates distortion of fibers due to long term rolled storage; desiccation; tears and holes.

Framing damage - fryable media such as charcoal or pastels resting on mat bevel or in between mat and glazing; faded paper or pigments; cockling for improper mounting; acid migration from non-archival products; objects stuck to glass from exposure to moisture.

Paper - encapsulation

Encapsulation is a preventative conservation treatment using two sheets of polyester film held together with double side adhesive tape. Encapsulation reduces damage to documents when being handled without reducing accessibility; makes it possible to handle fragile documents; creates a micro-climate around encapsulated document; prevents acid transfer; treatment is 100% reversible, quick and inexpensive.


  • 5 mil polyester film (mylar)
  • 3M #415 double sided tape, 1/4"
  • Step 1: Cut two sheets of mylar 1 1/2" - 2" bigger than item to be encapsulated.

    Step 2: Wipe the film with a lint-free cloth to remove dust particles and oil from fingerprints.

    Step 3: Center item on bottom sheet.

    Step 4: Place strips of double sided tape around object leaving at least 1/4" margin between item and tape. Only remove the backing from one side of tape. Leaving spaces between tape will help air to circulate and prevent moisture condensation.

    Step 5: Remove dust from top sheet, align with bottom sheet.

    Step 6: Use brayer to gently force air from between sheets.

    Step 7: Place a weight over the mylar to hold everything in place and remove backing from double side tape.

    Step 8: Round corners of mylar encapsulation.


    XXX. Ellis, M.H. (1987). The care of prints and drawings. Nashville: American Association for State and Local History. (pp. 16).
    XXXI Glossary of terms useful in conservation (1976). Ontario: Canadian Museums Association