The survival of anything made of paper depends on the properties of the paper itself, the materials applied to it, and their effect on each other. In contrast to materials such as textiles, where older pieces are usually more fragile than newer ones, the opposite is often true of paper. If stored in a good environment, paper made in Europe from the late medieval period through to the mid-19th century tends to be in good condition. Paper made after the mid-19th century, however, may be affected by the poor quality materials from which it was made. Thus some modern papers only have a lifespan of a few decades.
From the mid-19th century onwards, increasing demand for reading material coincided with the development of mechanised papermaking and printing. This allowed the widespread use of cheap and plentiful wood pulp as the raw material for paper making. Wood pulp can simply be ground up and then made into paper. This type of pulp, known as groundwood, contains all the acidic components that are present in the wood. Paper made from groundwood pulp, e.g. newspaper, is cheap to produce but inherently very acidic.
Types of paper
Paper has been used to create fine art and literature since it was invented in China over 2000 years ago. Paper is made from a range of natural materials which vary depending on the county and culture of origin, such as Japan, China and India. Within the European tradition there are two basic categories: hand-made and machine-made paper. Even so, there is huge variety in weight, texture and colour. Documents and works of art on paper consist of both the paper and the ink, paint or other applied decoration.
The earliest European paper was handmade from plant fibres, typically recycled linen or cotton rags. These were shredded, soaked and macerated to separate the fibres, producing a watery pulp that was strained through mesh moulds to make sheets of paper. Paper produced in this way is very absorbent and acts like blotting paper. It can be difficult to produce sharp lines or clear text because the wet ink or paint bleeds and spreads out.
To prevent ink absorbing, the surface of the paper is 'sized'. The term sizing was borrowed from artists, who pre-treated wooden panels and canvasses with dilute glue, called size, to seal the surface. The earliest paper sizing involved dipping paper into dilute gelatin to give it a harder, less absorbent, more resilient surface. Alum (aluminium potassium sulfate) was added to the gelatin to help bond it to the paper, and to retard mould growth. Paper that is hand-made from linen or cotton has long fibres that make the paper stronger. In addition, this type of alum size is usually chemically stable.
Acidity is one of the most important causes of damage in paper as it weakens and eventually destroys the fibres that make up the paper. As a result, paper made from groundwood pulp breaks down rapidly from within. The first sign of this is that the paper becomes yellow, then brown, and increasingly brittle. For example, newspapers are made from groundwood pulp, and the acids in the paper cause it to discolour and become brittle. Breakdown of the newspaper from within speeds up with exposure to light and/or high humidity. Wood pulp can be chemically treated to remove acids and impurities. Paper made from purified wood pulp is more expensive but lasts longer than that made from groundwood pulp. However, in the past, its lifespan was still limited because it was almost always treated with alum-rosin size.
Alum-rosin size was introduced in the mid-19th century, alongside wood pulp. It was made from a mixture of alum, in this case aluminium sulfate, and rosin, the resinous material left over when turpentine is distilled. This type of alum is different from the earlier type and is not chemically stable. Alum-rosin size was cheap, could be added whilst the paper was being made rather than as a separate stage, and produced an excellent surface for printing. Unfortunately, in moist conditions it generates sulfuric acid, which attacks the paper, turning it yellow and making it very brittle.
Another problem that can damage paper (usually in books, drawings and letters) is caused by the type of ink that was used. Iron gall ink, manufactured from tannin (galls), vitriol (iron sulphate) gum arabic and water, was used in Europe from around the late 12th century. Depending on how the ink was originally made, iron gall ink can 'burn' holes right through it. A similar problem occurs with verdigris, a green pigment made from copper, which was often used in older Islamic books as a green border around the text.
The first indication of iron gall damage is a brown halo around the ink lines. It is made worse by damp conditions and while dry conditions will slow the process down, they cannot prevent it.
The term 'foxing' describes disfiguring small yellow brown spots or blotches on paper. Two main causes are mould and iron contaminants in the paper. Moulds feed on the paper itself, as well as any dirt or organic material on it, for example, finger marks, food stains and squashed insects. Tiny metal impurities can be found in paper as a result of the original manufacturing process or from dirt and pollution. Damp conditions encourage mould growth, and will cause iron contaminants to rust. In some cases a conservator may be able to reduce the disfiguring effect of foxing, but in many cases you simply have to accept this old damage.
First decide if your paper and books have historical, aesthetic or sentimental value. If you think they have significant monetary value, consider having them valued, insured and professionally conserved.
The cost of neglect and poor quality repairs is high. Because books are not usually decorative objects in their own right, and thus not displayed, there is often a resistance to the cost of professional conservation. You should balance this against the monetary and sentimental value of your books.
Never take a book off a shelf by putting your finger on the top of the spine and pulling the book towards you – this damages the head-cap, which will eventually break off. Try and remove a book by either passing your hand over the top and gently pushing from the fore-edge or by
pushing the flanking books further forward so that you are able to wrap your hand around the spine of the book and firmly grasp each side. Ensure you support heavy books with the other hand underneath.
Care of paperbacks
The most common type of binding in the modern home is called 'perfect' binding and is used for magazines and journals, modern paperbacks and some modern hardbacks. Both cover and pages are stuck together at the spine edge by a thick layer of hot melt glue. This is the cheapest type of binding and is intended for the throwaway market. It is often combined with the use of poor quality, acidic paper.
Once the adhesive along the spine dries out or breaks, pages begin to drop out. You can put the book into a book box and store it. This will at least keep the parts together and minimise further damage. If the book is of value, a professional conservator could repair and rebind it.
Oversize family bibles are particularly vulnerable to damage from reading, handling and poor storage. Often the structure is not strong enough to carry the weight of the text block and boards. Also, the older the volume the more likely the binding will be damaged and brittle, so it is important to support the whole structure and weight of the book when you pick it up and as you read. Foam wedges are the best solution.
Typical damage caused by unsupported opening
Opening a book flat on a tabletop concentrates the strain onto the weakest point of the binding, the joint between the spine and the front and back boards. Once these joints are broken, the covers and spine can break off, sewing can break, the text block may split and pages start falling out. If left untreated, the book will eventually be destroyed.
Normal photocopiers require books to be pressed flat on the glass bed. This damages the sewing, spine and joints. Libraries usually have special photocopiers that allow a page to be photocopied without forcing the book flat: if you have to photocopy, use one of these.
Using foam wedges for large books
Foam wedges fully support the boards right up to the joint with the spine. This means that almost all the weight of the book is taken by the foam wedges, not the spine and the joints. They also restrict how far the book is opened and prevent you from accidentally breaking the spine by forcing the pages too flat. Snakes (curtain weights: a small chain of lead weights sewn in to a tube of fabric) can be rested on the pages to keep the pages open without damaging the spine (suppliers: Preservation Equipment or Conservation By Design).
How the foam wedges are used depends on whether you're at the beginning, middle or end of the book because the shape of the spine changes as you read. Use additional flat foam blocks to support the book in its natural shape if it is opened towards the beginning or end. Alternatively, you can roll up clean, dry hand towels to support a book without foam wedges.
On modern hardbacks and older books, particularly large books, the boards are bigger than the text block. When they are stored upright on a bookshelf, the text block is unsupported and will slowly 'drop' down to the shelf. In the beginning, this process distorts the spine: the top of the spine flattens, the bottom of the spine is pushed outwards and eventually the joints between the boards and spine begin to tear. This damage can be prevented by storing the book horizontally or, if vertically, within a book 'shoe'.
Book shoes are tailor made by conservators to fit an individual book. They are made from archival material and incorporate a text block support to compensate for the gap between the text block and the shelf. Slip cases, which are like a book shoe but enclosed on the top, are not recommended because they make it difficult to remove the book without pulling on the joint and don't support the text block.
Packing and storing books
Avoid storing books in attics and basements and keep boxes slightly off the floor and away from the walls. This prevents damage from minor flooding and the airflow will help avoid insect damage and mould.
When packing books in storage boxes, make sure the spine is supported otherwise the boards, spine and textblock can come apart from each other. Lay books flat, reverse spines, with largest at the bottom and smallest at the top, ensuring not too many in a pile, or pack books spine down with similar sized books together. Do not pack books on top in any left over space.
Individual, archive quality, permanent boxes are the best option for medium to long term storage of valued books, rare items, parchment textblocks and parchment covered books, leather bound volumes and books with fittings. Though expensive, the box should be an exact fit for the book and help protect it from damage caused by light, heat, humidity and pollution. Phase boxes are individually tailor-made from archive quality box board. They are the cheapest way to keep books you value in good condition. They can be good for books that have fittings such as metal clasps or decoration that would otherwise rub or catch on neighbouring books.
Diecut boxes are commercially produced, come in standard sizes (which may not fit your book exactly) and are delivered flat packed. They are made from archival quality folding box board and can be useful for magazines and comics. However, some sizes can only be purchased in large quantities.
Four flap enclosures are a cheaper and simpler method of protecting smaller books, paper pamphlets and brochures etc that are vulnerable or have loose pages. These can be simply made from an archive quality Manila or Kraft paper or thin card as for the wrappers below.
Wrapping is the cheapest option; it acts like a dust jacket and is a good choice for damaged books, e.g. if the covers or pages are loose or if the bookcase is in direct sunlight. Wrap a book in a sheet of heavy weight archival quality paper or thin card, for example Kraft (120gsm), Manila (225 gsm) or Cover (300gsm) paper, depending on the size of the book. Choose paper that is lignin free, acid-free, buffered, and with a pH of 7–8.5.
Where boards have become detached and none of the above are feasible, you can use linen tapes to tie the boards back on and prevent damage to the text block.
Leather has been chemically processed (tanned) so that it does not putrefy when it gets wet. Alum tawed leather has only been partly tanned by treatment (tawing) with alum. In the right conditions, it is very hard wearing and durable. However, if it gets damp or wet it will deteriorate and be damaged. Untanned skin such as parchment or vellum, which has been limed, stretched and dried, can also be hard wearing and durable. However, if it gets wet it will contract and begin to putrify.
Avoid using leather dressing on books. It doesn't help preserve the leather and can in fact be very damaging, particularly when too much has been applied.
Dealing with red rot
This describes leather that appears powdery, orange-red and brittle. This is caused by a combination of the original tanning method (vegetable tanning) and pollution. Sulphur dioxide pollution reacts to form sulphuric acid that attacks the leather from within. Once the damage has occurred, the only thing you can do is try to limit the damage caused by handling.
You may wish to box or wrap the book with materials that absorb any acids that the deteriorated leather gives off. Using leather dressing or other materials such as Vaseline will not help (and may cause more damage) because the problem is not on the surface but deep within the leather itself.
Regular book maintenance
Removing books from shelves once or twice a year to dust them will keep them clean and is a good way of noticing problems with mould or insects before too much damage is caused. Set up a table with some clean paper on it, outside if it is a warm, dry day. Take each book in turn, hold it firmly closed by the fore edge and using a soft bristled brush, for example an old-style bristle shaving brush, lightly brush off the dust.
Work from the spine edge to the fore edge, otherwise you will end up pushing the dust down the spine. Avoid using a vacuum cleaner because of the risk of sucking off any loose fragments. This method isn't appropriate if the pages are badly distorted, cockled or damaged because dust can get into the pages. Vacuum or wipe down the shelves before replacing the books.
If the paper is in good condition, it may be possible to remove dust and dirt from the margins of the pages using a Chemsponge, also known as a chemical or smoke sponge (suppliers: Conservation By Design or Preservation Equipment). These are made from vulcanised rubber and should be used dry – no liquid is required. They work by trapping dirt in the surface of the sponge. When this happens, simply cut off the dirty surface to expose clean sponge. A Chemsponge will not remove mould damage, foxing or stains and is not a good idea if the paper is brittle or torn, or if the surface of the paper looks 'fluffy'.
Clean only the margins, and take care not to clean printed areas or illustrations because you may smudge or remove the ink. Leave annotations, notes and doodles in the margin as they may be historical evidence that adds monetary value and interest to your book. It is important to wash and dry your hands regularly whilst cleaning otherwise you will transfer more dirt than you remove. Cut off a small piece of the Chemsponge, about 25 x 25 x 10mm. Stroke this over the dirty area of the margin very lightly.
If a Chemsponge doesn't remove the dirt, you could consult a conservator. If fragments of paper are removed, stop immediately. If you find pieces of paper in the book, they should be stored in an envelope with a note saying where the fragment was found within the book.
Cleaning mouldy books
Mould growth is caused by high relative humidity or dampness, combined with poor air circulation. In terms of caring for your antiques, what matters is relative humidity. Relative humidity measures the amount of moisture that is in the air relative to the maximum amount of moisture that the air could hold at that temperature. If conditions become dryer and relative humidity drops below 70%, the mould will become dormant, but will reactivate again if relative humidity rises.
If you have mouldy books, try to locate the source of the dampness, e.g. leaks or books against a cold exterior wall, and address the underlying cause of your problem. Assess whether the mould is active or dormant by testing it carefully with a fine brush. If the mould is dry and powdery it is likely to be dormant, whilst if it is soft and smeary it is probably active. If the mould is active, move the books to a warm dry area until it becomes dormant.
To remove mould itself, take the book/s outdoors on a warm, dry day. Hold each book so that it remains firmly closed, to prevent contamination of the text block, and clean as previously described. Clean the shelf area thoroughly with a commercial fungicide or a solution of 5–10% bleach, wipe/rinse the shelf with water to ensure all bleach residues are removed and allow them to dry before replacing the books.
What not to do ...
Don't use old fashioned cleaning remedies
Bread is a traditional dry cleaning material used to remove dirt from paper. If you rub a piece of fresh white bread between your fingers, you will see that it is quite effective in picking up dirt. The slight stickiness of bread is the reason why it works and also why it can be a problem. It can leave a sticky residue behind that will attract more dirt. Oily residues or small crumbs trapped in the paper fibres will support mould growth and encourage pest attack.
Don't cut down documents or drawings to fit a frame
In the past, works of art on paper were sometimes cut down to fit a frame, mount or album. This may be done by some commercial mounters today. However, it is important not to cut down documents or works of art because you may remove important historical evidence by accident, such as signatures, margins and plate marks, which add to the provenance and value of the piece.
Don't laminate paper
Lamination is used to reinforce paper by sealing it between sheets of plastic, using heat and pressure. Whilst it is fine for disposable papers that are handled a lot, it is not appropriate for historic or valued paper. Unfortunately, the plastics used are chemically unstable and become yellow and brittle in time, producing acids that attack the paper, ink and pigments. Lamination is irreversible because the heat and pressure mean the plastic is thoroughly stuck to the paper, so if you value your paper, don't laminate it.
Don't use pressure-sensitive tape for repairs
One of the worst things you can do to paper is to try repair tears with pressure-sensitive tape such as sticky tape, sticky-backed plastic or masking tape. These are usually made from a thin, flexible backing, combined with an adhesive that is tacky at room temperature.
In the short term, removing pressure-sensitive tape can remove the top layer of paper fibres. In the medium term, the backing drops off, whilst the adhesive left behind on the paper attracts dirt and can stick to and damage other papers stored against it. In the long term, the adhesive can seep into paper, leaving irreversible yellow or brown discoloration. If the adhesive becomes acidic as it ages, it will also attack the paper.
Avoid using tape on the back of paper, for example when making home-made mounts. In the long term, the adhesive from the tape may creep through the paper and produce irreversible patches of discoloration on the front.
Modern pressure-sensitive tapes use an acrylic adhesive. These don't discolour too much and don't soak through the paper as they age, although they can soak in a little way depending on how porous the paper is. However, they cannot be dissolved in water or solvents and often cannot be removed without damaging the paper.
'Archival quality' pressure-sensitive tapes are also available. They may be described as chemically stable, non-yellowing, acid-free or removable using solvents or water. Just because they are 'archival' doesn't mean you can use them on your valued art works or documents. Residues of adhesive can be difficult or impossible to remove. Also, it may not be possible to use water or solvent without damaging the paper. Reversibility is not just about a material, but about what it is applied to as well. Tapes that use a water soluble starch adhesive are available and are a better alternative.
It is best not to use any kind of pressure-sensitive tape.
Modern domestic adhesives, such as UHU, Superglue, Blutack, Copydex, Pritstick and rubber cement glues are all unsuitable for valued paper. The adhesive will fail in the long term and as the products break down they will stain, damaging the paper itself. It can be difficult to remove glue that has dried up, and become dark and brittle.
Don't use adhesive tape to encapsulate paper
Encapsulation is sometimes recommended as an alternative to heat sealed lamination. The paper is placed between two sheets of chemically inert plastic, which are held together with double sided tape around the edges, but not in contact with, the paper. The paper is held in place by the electrostatic charge of the plastic.
The main problem with this is the use of double sided tape, which usually has a very strong adhesive. If you accidentally touch the paper with the tape, there is no 'forgiveness'. If it is pulled off, the tape will take the top layer of paper, ink or paint with it. Accidental contact can happen if there is slight movement of the paper when encapsulated, or when separating the plastic sheets to take the paper out. Enclosing paper between proprietary sleeves that are heat welded on two or three sides is a good alternative.
Don't use dry mounting
This is a technique used to mount photos, papers and posters, particularly if they need to be flattened as well. Dry mounting uses thin paper that has been impregnated with adhesive. The tissue is placed between the back of the paper that is to be mounted and its supporting paper or card. Heat and pressure are used to melt the adhesive in the tissue, sticking the paper to the mount. As always, problems and damage are likely as the adhesive ages; dry mounting is a process very hard to reverse.
Don't use paper clips, staples and self-adhesive notes
These are all intended for use on disposable office paperwork. They are not suitable for either temporary or permanent use on valued paper or works of art. Metal clips and staples will corrode, leaving rust stains on the paper. Paper clips often tear paper when they are removed, and can leave a permanent distortion behind in the paper. Self-adhesive notes leave a residue behind. Coloured folders or ribbons can stain paper in damp conditions, whilst rubber bands cut into paper when they are new, then become sticky as they age and perish.
If you find any of these on your antique papers, carefully remove them. If you think they are of interest, keep them separately, for example you could take a photograph of a document bound with coloured ribbon and then keep a coloured ribbon in a page protector next to the original letters.
Produced by the Paper, Book & Paintings Conservation section, V&A