STORAGE TIPS |
Although Scandoc Imaging focus is on converting your paper documents to digital format proper storage of your valuable documents and books are just as important. However, no matter how careful you are in storing your documents they will eventually deteriorate or could possibly be destroyed by light, mold, fire, water and/or insects and rodents. Let Scandoc Imaging convert them for longevity. Introduction In providing these guidelines, which are not intended as all-inclusive, Mr. Clark noted: "By following the procedures outlined in the several sections, much can be done to properly restore materials to usable condition without causing further damage. A word of caution however: the methods should not be applied indiscriminately to everything. A professional conservator should be consulted when dealing with documents of great value or material in an advanced stage of deterioration. Without such consultation it is better to do nothing than to do the wrong thing." This edition was revised by David Anderson and Susan Rogers of the Archives Staff (Maine State Archives), following Mr. Clark's earlier 1982 edition. Paper Papers made in the period beginning with the Twelfth Century and ending with the middle of the Nineteenth Century were strong and durable; and many books and documents published prior to 1850 are still in excellent condition. Modern paper is generally made from wood fibers which have been mechanically ground for newsprint or chemically purified for books and writing papers. Finer papers also contain cotton or linen fibers. Most modern papers, unless designated as acid-free or permanent/durable, have an expected useful life of less than 50 years. Causes of Deterioration The use of groundwood or unpurified wood fibers rather than chemically purified pulp is another factor in modern paper deterioration. The lignins or "glues" which hold the fibers together as wood degrade to form acids which weaken the paper. Although most papers contain some unpurified wood fibers, the most common example of groundwood paper is newsprint. Other factors influencing paper deterioration are: atmospheric pollutants such as sulfur dioxide, nitrogen dioxide, and ozone; the invisible radiation of sunlight and fluorescent light; the short wave lengths of visible light; the growth of microorganisms such as mold and bacteria; and insects and rodents which feed upon the paper. Temperature Thus, the life of paper can be extended by lower storage temperatures; theoretically, the useful life is almost doubled at each 10-degree Fahrenheit decrease in temperature. A constant storage temperature of 68-degrees Fahrenheit is considered ideal, being high enough to be comfortable to workers and low enough not to damage materials. Widely ranging fluctuations in temperature are extremely damaging, as are high temperatures. Therefore, papers and books should never be stored in attic areas where wide fluctuations are common, and temperatures approaching 150-degrees Fahrenheit may occur on summer days. Humidity High relative humidities (in excess of 68%) cause the swelling and warping of paper fibers and hasten acid deterioration. Also, high humidities in the presence of metal staples and paper clips will cause rust stains, even though no actual water damage occurs. Low humidities (below 40%) will cause paper to dry out and become brittle; often in this range, fragile pages will stick together as a result of static electricity, and may tear if care is not exercised in turning pages. Seasonal fluctuations of less than 10% in winter to more than 90% in summer are damaging to paper materials. Modern book papers should be stored at 40% to 50% rh; leather bindings, at 45% to 55% rh; and vellum or parchment, at 50% to 60% rh. Overall, a good compromise is storage at 50% rh, with an acceptable range of 45% to 60% rh. Fluctuations within the range should be kept to a minimum. Humidity levels in a small storage area can be maintained with a small air conditioning unit, a dehumidifier and/or a humidifier. Basement storage areas are generally not desirable due to possible flooding and ordinarily high humidity levels. As inexpensive commercially-marketed gauges are frequently inaccurate, the relative humidity of the storage area should be monitored with a dry-wet bulb thermometer or a sling psychrometer. Both record the temperature difference between a dry bulb and a wet bulb thermometer; the evaporation which occurs around the wet bulb thermometer is directly related to the humidity. A chart or sliding chart rule gives the relative humidity for the given conditions. Flattening Folded or Rolled Materials A new plastic garbage can serves as a useful container, with a pan of water on the bottom and, above, tiered shelving of plastic screening on which to place the materials. The paper must not be in contact with any condensed water which forms on the wall of the container. Alternatively, the folds or the rolled materials may be wiped with a DAMP sponge. The danger in this method is the possibility of smudging inks or colors which are not water-resistant. With either method, once the paper has absorbed moisture, flattening will proceed more easily. Once flattened, the paper should be allowed to dry under pressure. Individual pages or small groups of pages should be separated with white blotter paper or cardboard (chipboard), then covered with a piece of plywood weighted down evenly with books or some other heavy material for one or two days until dry. Mold However, mold spores are always present in the air and in the dust that settles on documents; and, if the recommended conditions are not maintained, the danger of mold growth and damage to documents exists. A relative humidity of 70% combined with high temperatures encourages the growth of mold or mildew, although some molds will grow at temperatures as low as 40-degrees Fahrenheit if the humidity is high. Stagnant air conditions also favor mold or mildew attacks. Once started, mold is difficult to control and serious damage may occur before the condition is detected; prevention is far easier than correction. The environment should be monitored on a regular basis to avoid the conditions favoring the growth of mold. In the initial stages, mold growth may be little more than a nuisance. The visible evidence can be brushed away, and the item can be stored under recommended conditions without further concern. In later stages, mold will digest the material upon which it grows, resulting in staining (foxing) and loss of strength of the material. Atmospheric Pollutants Certain gases such as sulfur dioxide, hydrogen sulfide and nitrogen dioxide originate from burning fossil fuels and are most serious in industrial areas. As large and expensive filtering devices are necessary for removal, no economical means of protection is available for the small collector. Some of the compounds are not dangerous until combined with other compounds to form acids; for example, sulfur dioxide is catalyzed by other airborne compounds to form sulfur trioxide, which unites with water vapor to form sulfuric acid. Ozone, a pungent gas generated by the interaction of sunlight and nitrogen dioxide from auto exhaust and one which is also prevalent around electric motors and after thunderstorms, causes the oxidation and consequent embrittlement of paper. As dirt and dust carry absorbed pollutants which can be abrasive to books and paper, air in a storage room should be filtered, with frequent changes of filters in the system. Where filtration is not possible, objects can be stored in closed containers; if used, plastic bags should not be tightly sealed. Exhibit cases which are sealed against dust and dirt should provide air circulation through filters. As stagnant air increases the possibility of mold growth, any material stored in closed containers should be checked frequently. Also, the area should be cleaned and vacuumed regularly to eliminate dust and dirt buildup on any materials. Light The visible effects of light include: the bleaching or fading of paper; and the yellowing or browning such as rapidly occurs with newsprint. Not immediately visible is the breakdown of fibers into smaller units, causing the paper to disintegrate. Unfortunately, the reactions continue after the source of the problem is removed, although at a slower rate. Other factors being equal, paper stored in complete darkness will last far longer than that which is subjected to light. However, as totally dark storage is not usually practical, other precautions must be taken. Paper should never be stored in direct sunlight or under unshielded fluorescent tubes. Special ultraviolet-filtering materials, such as UF-3 Plexiglas or Acrylite OP-2, may be used to shield windows or fixtures. Valuable documents should be deacidified and alkaline-buffered by a competent paper conservator, and stored in acid-free file folders in an enclosed container. If a document is to be mounted for display under ultraviolet- filtering material, the document should be matted with acid-free board, preventing direct contact with the protective filter; the latter contains a yellow dye which might otherwise discolor the document. Even when shielded, the document should be hung to avoid sunlight and fluorescent light. Frequently, display cases will contain fluorescent lights which are damaging to the displayed material unless shielded with special plastic sleeves of ultraviolet-filtering material which slip over the tubes. Although these shields are expensive, their use is essential as the displayed items are close to the light source and thus receive a high amount of ultraviolet radiation. A familiar example of acid migration is the brownish discoloration commonly observed where newspaper clippings have been stored in old books. Insects and Rodents The most certain way to avoid insects and rodents is to practice good housekeeping: keep food away from the storage area, screen windows, and kill any insects or rodents observed. As a further precaution against insects, one can place small open containers of paradichlorobenzene (the active ingredient of moth crystals) on bookshelves. Paradichlorobenzene is a poison and must be placed beyond the reach of children! If insects are found in stored documents, one can place them in a covered container with paradichlorobenzene for three weeks, an ample time to eliminate insects and their eggs. Paradichlorobenzene is available in drug, discount and general stores under various trade names. The material readily vaporizes and requires periodic replacement. Silverfish may be eliminated with a sweetened mixture of 1-3/4 cups wheatflower or oatmeal ground to flour, 1/4 teaspoon sodium fluoride (available in drug stores), 1/2 teaspoon granulated sugar, and 1/4 teaspoon salt; once mixed, the powder can be placed in shallow cardboard boxes loosely covered with crumpled sheets of paper. The mixture is ample for several good sized rooms, and the boxes may be placed in areas where silverfish are known to occur. Wheat flour or Oatmeal (ground to flour) 1 3/4 cups Sodium fluoride (available in drug stores) 1/4 teaspoon Granulated sugar 1/2 teaspoon Salt 1/4 teaspoon Mix the ingredients thoroughly and it is ready to use. This powder should also work on various other insect pests. Sprays should be avoided because of the chance of staining materials. Proper Book Handling Books leaning to one side will be damaged along the spines. Books should stand upright, and, in the absence of book ends, should be supported by lying several volumes flat against the standing volumes. Large books should be stored flat. Cleaning Books Take one book at a time, and hold the book firmly closed to prevent dust from entering the pages. With the spine up, tip the head forward and down; dust the top of the pages thoroughly, stroking downward; then dust all other surfaces.. Certain erasers may be used to clean book covers and any surface dirt from pages. However, in cleaning paper, a soft bristled brush should be tried before resorting to erasers. Erasers, in order of decreasing abrasiveness, are Faber's "Pink Pearl and Magic Rub" and art gum erasers. For paper, the "Opaline" Dry Cleaning Pad or Dietzgen's "Skum-X" can be used; using the latter two, sprinkle eraser crumbs over the soiled area and gently rub in a circular motion with the flat of the fingers. To lessen the likelihood of damage, work from the center of the page to the edges. Remove all eraser crumbs when finished. If any doubt exists about the strength of the paper, leave the page alone. Care must be exercised to avoid damage to the gold stamping of titles on book covers which can be ruined through improper erasures. The erasers referenced above are available through stationery or drafting supply stores. Leather Bookbindings Leather produced before the 17th Century was of fine quality and very long-lasting; whereas that produced since the late 17th Century frequently shows rapid and severe degradation. The older vegetable tanning processes (the type usually used for bookbinding) may have left protective or buffering salts that reduced deterioration; apparently, these salts are missing from modern leathers. Strong mineral acids from air pollutants and sulfuric acid left by the tannage process contribute to the destruction of leathers. Relative humidities below 40% cause leathers to dry out and deteriorate; on the other hand, high humidities and high temperatures speed up the chemical deterioration of leather. Light, even indirect sunlight, will produce fading or darkening of dyes in leather; valuable bindings should be protected in boxes made from opaque and inert materials. The flexibility and suppleness of leather depends on the sliding action of fibers which can become dried out if not lubricated. Thus, an important step in the preservation of leather is replacement of those natural oils which may have oxidized. In some cases before lubrication, the leather may require rehumidification to restore moisture content. The sulfuric acid used in processing modern leathers is extremely difficult to remove; also, in the process, the natural buffering salts are washed out of the skin. The lost salts can be replaced with potassium lactate (see SOURCES) which serves as a buffering salt and neutralizes any strong mineral acids. Cleaning Leather Bookbindings If a binding is dirty, surface grime can be removed with a soft lintless cloth slightly dampened with water, potassium lactate or saddle soap. One should first try to clean an inconspicuous spot to be certain darkening will not occur; and, if saddle soap is used, all soap residue must be removed, using clean soft rags. Treatment With Neat's-Foot Oil and Lanolin Apply the dressing with a pad of cheesecloth or cotton using a patting motion; brushes are not satisfactory, as one has little control over the amount of dressing being applied. In patting on the dressing, one must use great care to avoid staining any paper or cloth parts of the cover or any pages of the text. Several thin coats, applied carefully and thoroughly to small areas at a time, are preferable to one heavy coat. Excessive dressing may bleed through the spine, staining the text and embrittling the pages as the oil oxidizes; a piece of waxed paper inserted between the covers and the text will reduce this as a possibility. Before use, the treated books should allowed to absorb the dressing for a period of 12 to 24 hours. The treatment should be repeated every two to five years, depending upon storage conditions; when the leather begins to feel dried out and somewhat brittle, another treatment is necessary. Once leather has reached a powdery consistency, the treatment is not effective. Polyvinyl acetate emulsions, lacquers and varnishes should never be used on leather bindings; they may cause bindings to stick together. The above are general suggestions which should not be applied indiscriminately to all leather-bound books. If dealing with very valuable books, one should consult a professional conservator. Repairs Pressure sensitive tapes such as the cellophane "Scotch" tape and "Magic Mending" tape are not appropriate for repairs as both will cause stains and are difficult to remove without damage to the document. Rubber cements will also cause stains; and, as they dry out, will fail. Polyvinyl acetate emulsions (PVA), such as "Elmer's Glue-All" become impossible to remove without damage to the paper; these emulsions are often acidic and will discolor and deteriorate the paper. Gummed paper tapes should be avoided as the tape is often acidic causing discoloration of the document. Most commercially available pastes are acidic, due to the addition of alum; these will become brittle and discolored and will cause discoloration and deterioration of the paper to which they are applied. As the pastes are water-based, they may cause cockling of the paper and may cause certain inks and colors to run. To check for water solubility of inks, moisten a cotton tipped applicator with distilled water and carefully touch the different inks or colors (one at a time), examining the cotton for any color transfer and spot checking for running. If none is exhibited, a paste may be safely used. The best adhesive is a rice paste which can be removed with water; that is, the repairs are reversible. Using Rice Paste and Tissue to Repair Tears Although the various Japanese tissues may be used, a less expensive alternative is Troya 6-1/2 lb. lens tissue which is available in 24" by 36" sheets from TALAS; not as strong as the Japanese tissues, it does an adequate job for most purposes. Determine the direction of the fibers by tears parallel to the edges of the tissue; tears will occur most easily and be straightest in the direction of the fibers. For most repairs, the fiber direction should be across the tissue, giving the repair maximum strength. The width of the repair strip will depend on the size of the repair; however, a piece 1/2" wide or less should be adequate for most situations. To provide maximum concealment, the strips should be torn rather than cut with scissors. Using a small artist's brush wetted with water, draw a line where the tear is to be made; the water weakens the tissue and allows it to pull apart, leaving the edges feathered. Also needed are a stainless steel artist's knife or spatula to apply the paste and a clean flat working surface, such as a piece of plywood covered with a plastic garbage bag which has been washed to remove any oils from its manufacture. Press the edges of the tear together lightly with the fingers, making certain the parts go together properly while applying a small amount of paste. Apply some paste to a strip of tissue slightly longer than the tear, gently working the paste into the tissue with the spatula; the tissue will become transparent as the paste penetrates. Remove any excess paste. Pick up one end of the tissue with the tip of the spatula and carefully place it over the tear. Using the spatula and working from the tear to the edges of the tissue, gently apply the tissue to the item being repaired, blending the tissue fibers into those of the document. Any tissue that protrudes beyond the edge of the paper can be folded over to the backside of the page, giving reinforcement to the tear at the weakest point; i. e., the edge. When the repair is damp, but no longer sticky, press the item to prevent any curling. To eliminate the possibility of any sticking, used waxed paper over the repair and press the page between chipboard or white blotter paper, using a light weight. Long or irregular tears should be done with several small overlapping strips. Although this method is best tried first on papers of little importance, if something does go wrong, the tissue and paste is easily removed with water. After each repair, the working surface, tools and hands should be cleaned with water. Rice paste is a satisfactory adhesive for any project. Protective Encasement The process requires no expensive equipment and is performed by personnel who can be easily trained in the procedure. The final product, an envelope sealed along all four sides, protects the most fragile paper from further fracture and from harm or defacement. The document is immediately available for examination. Materials: Polyester film: 3-mil for small or medium size documents (to 12" by 18"); 5-mil for larger documents; and 7-mil for large maps and posters. Available options are Dupont's Mylar Tools: Method: 2. Place the grid on the work surface, aligning the edges of one sheet of film with the grid. 3. Wipe with a lint-free cloth to remove any dust particles and to create a static electrical charge in the film. 4. Center the document on the film, placing a weight upon it. 5. Using the grid as a guide, place a strip of tape on each of the four sides of the film, 1/8- 6. Dust the surface of the second sheet of polyester that will contact the document. Since 7. Removing the weight, place the second sheet over the document and squeegee to eliminate air pockets between the materials. 8. Place a weight in the center of the cover sheet. 9. Peel the backing paper from one strip of tape and then from an adjacent strip. 10. Squeegee along these tape edges. 11. Repeat for the other two sides. The top layer of film may be folded back and held in place with the second weight while the backing strips of the adhesive tape is removed from the corner as illustrated by the following diagram. Put the film back down over the exposed tape. 12. Squeegee over the tape firmly to assure a good seal and to eliminate air from the envelope. 13. Trim the envelope to within 1/16-inch of the tape. The extra allowance of film helps to 14. Rounding the sharp corners with scissors or a nail clipper will help to prevent injury to other documents or even cuts to people. Material so encapsulated must be stored flat to prevent the tape from loosening, thereby breaking the seal. Materials: Rubber bands should be avoided unless they are of natural rubber which, however, becomes brittle and breaks fairly soon. Regular rubber bands have been treated with sulfur to make them last longer. This sulfur oxidizes and with moisture forms sulfuric acid which discolors and damages the materials. Inks also pose problems. Most colors are simply dyes and will fade in time. Felt tips are bad because of fading and they smudge with just hand moisture. Ball point and felt tipped pens use inks of a volatile nature and may cause damage to materials. Pencil is permanent but smudges. Carbon based inks (India or drawing) and carbon typewriter ribbon are permanent and carbon typewriter ribbon are permanent and can be used for marking, etc. There are also permanent record inks based on a material found in lesser strength in permanent blue- black fountain-pen inks which can also be used. FIRE EMERGENCIES Be alert to defective wiring, fuel oil leaks, oily rags and litter on a regular basis; have chimneys and heating systems examined annually. Fire Extinguishers Use only those extinguishers which are appropriate to the material stored in a given area: Class A: ordinary combustibles; i.e., paper, wood, cloth. Water-based extinguishers for Class A fires may cause as much damage to the materials as the fire; and potassium bicarbonate dry powder extinguishers are used exclusively for Class B and Class C fires. A type suitable for Class A, Class B and Class C fires is the monoammonium phosphate dry powder extinguisher which is harmless to artifacts and documents if cleaned off materials as soon as possible after use. An extinguisher should be light enough for any person who might have to use it; and should be purchased from a reputable dealer through whom the unit can be serviced and recharged when needed. The National Fire Protection Association suggests the following as minimum ratings for non-industrial use: 2A:10 B:C with 5 pound of dry chemical 5 B:C or Halon 1211 and bicarbonate dry chemical 2A for water extinguishers In case of fire: Call the fire department Get any people out Fight the fire - but only if it is small and you are in no danger Sources Conservation Resources international, Inc. Process Materials Corp. TALAS
- a division of Technical Library Services Hollinger Corp. University Products, Inc. Light Impressions Corp. UF-3 Plexiglas and Acrylite OP-2 (tube or sheet form), UVA- 7, UVA-8 Potassium Lactate Solution and Neat's-Foot Oil and Lanolin Mixture: The Newberry Library Amend Drug and Chemical Co. |
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