Preservation of Illuminated Manuscripts
Encyclopedia
Preserving parchment
becomes more difficult when pigments, inks, and illumination are added into the equation. Pigments do not dye parchment; instead, they lie on the surface of the parchment and so are rather fragile. The goal of restoring illuminated manuscript
s should be to make them as resilient to damage while altering them as little as possible. Each individual manuscript, and even each individual page, must be considered as a separate object with different aspects that must be taken into consideration. This in turn will help determine the best course of preservation
or conservation treatment.
One of the best ways to become familiar with the variety of issues caused by various materials is to learn about how such manuscripts were made in the past and how they were subsequently treated in later years.
There are two different ways to identify pigments: invasive and non-invasive.
Invasive
These tests alter the manuscript in some way, usually by removing some pigment to test a sample. They are generally reliable but results are not always clear.
Non-Invasive
These tests do not alter the manuscript and are much better for conservation purposes than the invasive methods of identification. Some methods include:
Raman spectroscopy analyzes the molecular vibration
s of the pigments and uses this data to map out its chemical makeup. This works on the notion that every substance interacts with radiation in different ways, and these differing ways if measured can help identify the substance without having to take a sample. Unlike other non-invasive identification techniques the results of Raman spectroscopy are much more certain. It is even possible to analyze a pigment beneath a glaze or other treatment.
As such, environmental conditions such as humidity
must be kept under control. Pigments add another layer to the problem, forcing a preservationist to fit environmental conditions to two different (and possibly conflicting) sets of ideal limits.
Problems can occur when parchment is exposed to high humidity for a long period of time. For example, collagen
in the pages could dissolve and stick together.
These problems are further compounded by the fact that pigments do not dye parchment; instead, they lie on the surface of the parchment and so are rather fragile. Pressing an illuminated manuscript pushes the pigment down, altering the image itself and likely causing damage (such as a relief effect to the other side of the page) so it is very important to not put any pressure upon images on parchment, especially when it is wet. This fact also has to be taken into account when cleaning dirt from the image and when encapsulating or framing illuminated parchment for an exhibition. There must be enough room between the image and the protective surface (such as Perspex) that the image will not be subject to rubbing if the parchment should expand with rising humidity.
Soluble nylon
was used until the mid-1970s when concerns over the material’s stability emerged. Parchment size was then favored until the mid-1990s when leaf gelatin
gained popularity. This is not to say that gelatin is always the best consolidant to use; no consolidation technique should be used without first considering the pigments and other materials involved, though. For example, gelatin causes white lead to become friable.
This problem is compounded by the flexible nature of parchment. One solution to this particular problem is to use some form of a cellulose ether such as methylcellulose
, instead of gelatin. Again, this is not necessarily the right choice for every situation.
There are a few basic requirements for any consolidation agent:
The ultrasonic mister is usually used in conjunction with a paper suction table to direct the mist at the media and prevent distortion
. This is not the best treatment for illuminated manuscripts that have printing on both sides, though. In this case it is better to forgo the suction table and instead use the lowest setting on the mister and to monitor the process carefully.
Problems may arise if condensed mist falls onto the parchment from the nozzle so it is advisable that the device be placed on the floor or a similarly low level to coax mist to drain back into the mister instead of falling upon the parchment.
.
Gore-Tex now has controllable pore size and can block out many liquids, including liquid water and many conservation chemicals. Water vapor can still pass through the pores, though, so it is possible to hydrate the parchment and remove a crease without introducing liquid water to the pigmented image. This can be achieved by sandwiching a manuscript in Gore-Tex in varying ways to achieve the desired results.
can be made transparent enough to do this but great care still needs to be taken.
Parchment
Parchment is a thin material made from calfskin, sheepskin or goatskin, often split. Its most common use was as a material for writing on, for documents, notes, or the pages of a book, codex or manuscript. It is distinct from leather in that parchment is limed but not tanned; therefore, it is very...
becomes more difficult when pigments, inks, and illumination are added into the equation. Pigments do not dye parchment; instead, they lie on the surface of the parchment and so are rather fragile. The goal of restoring illuminated manuscript
Illuminated manuscript
An illuminated manuscript is a manuscript in which the text is supplemented by the addition of decoration, such as decorated initials, borders and miniature illustrations...
s should be to make them as resilient to damage while altering them as little as possible. Each individual manuscript, and even each individual page, must be considered as a separate object with different aspects that must be taken into consideration. This in turn will help determine the best course of preservation
Preservation (library and archival science)
Preservation is a branch of library and information science concerned with maintaining or restoring access to artifacts, documents and records through the study, diagnosis, treatment and prevention of decay and damage....
or conservation treatment.
One of the best ways to become familiar with the variety of issues caused by various materials is to learn about how such manuscripts were made in the past and how they were subsequently treated in later years.
Inks and pigments
The best distinction between inks and pigments is that ink is a colored liquid while pigments are colored particles suspended in a liquid. Areas colored by pigments usually have multiple layers of pigments and other mediums. The most important aspect of preserving pigments and inks is to identify their composition. Some techniques are not suitable for certain pigments and will do further harm.Some examples of issues with pigments
- Iron gall ink – very popular black ink; corrosive; can become brittle and fade.
- Lead white – darkens when exposed to air; reacts with verdigris and orpiment; generally stable to light.
- OrpimentOrpimentOrpiment, As2S3, is a common monoclinic arsenic sulfide mineral. It has a Mohs hardness of 1.5 to 2 and a specific gravity of 3.46. It melts at 300 °C to 325 °C...
– loses color quickly with exposure to ozoneOzoneOzone , or trioxygen, is a triatomic molecule, consisting of three oxygen atoms. It is an allotrope of oxygen that is much less stable than the diatomic allotrope...
; decays slowly in water; dissolves in hydrochloric acidHydrochloric acidHydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
and sodium hydroxide; reacts with lead- and copper-based pigments (such as lead white and verdigris); can corrode bindings; will not easily adhere to parchment and tend to flake off; cannot readily be consolidated with gelatin. - UltramarineUltramarineUltramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
– very stable to light but very unstable with acids; becomes friable and will crumble if outer skin is scraped, although this is hard to see at first without the aid of a microscope and can be made worse with the application of gelatinGelatinGelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
or other liquid consolidators. - VerdigrisVerdigrisVerdigris is the common name for a green pigment obtained through the application of acetic acid to copper plates or the natural patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea...
– reacts with lead white and orpiment; decays parchment; tends to become friable and is not easily treated with gelatin or other liquid consolidators; chelating agents such as calciumCalciumCalcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust...
and magnesiumMagnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
appear to prevent further degradation.
Identification
Identifying specific pigments is no easy task. Descriptions may be wrong or misleading and choosing the wrong treatment may cause irreversible damage.There are two different ways to identify pigments: invasive and non-invasive.
Invasive
These tests alter the manuscript in some way, usually by removing some pigment to test a sample. They are generally reliable but results are not always clear.
Non-Invasive
These tests do not alter the manuscript and are much better for conservation purposes than the invasive methods of identification. Some methods include:
- Microscopes
- Observation under UV, IRInfraredInfrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
, and visible light - X-ray fluorescence (XRF)X-ray fluorescenceX-ray fluorescence is the emission of characteristic "secondary" X-rays from a material that has been excited by bombarding with high-energy X-rays or gamma rays...
- Particle induced x-ray emission (PIXE-α)PIXEParticle-induced X-ray emission or proton-induced X-ray emission is a technique used in the determining of the elemental make-up of a material or sample. When a material is exposed to an ion beam, atomic interactions occur that give off EM radiation of wavelengths in the x-ray part of the...
- Raman spectroscopyRaman spectroscopyRaman spectroscopy is a spectroscopic technique used to study vibrational, rotational, and other low-frequency modes in a system.It relies on inelastic scattering, or Raman scattering, of monochromatic light, usually from a laser in the visible, near infrared, or near ultraviolet range...
- Raman spectroscop
Raman spectroscopy analyzes the molecular vibration
Molecular vibration
A molecular vibration occurs when atoms in a molecule are in periodic motion while the molecule as a whole has constant translational and rotational motion...
s of the pigments and uses this data to map out its chemical makeup. This works on the notion that every substance interacts with radiation in different ways, and these differing ways if measured can help identify the substance without having to take a sample. Unlike other non-invasive identification techniques the results of Raman spectroscopy are much more certain. It is even possible to analyze a pigment beneath a glaze or other treatment.
Properties of parchment
Parchment is hygroscopic.Hygroscopy
Hygroscopy is the ability of a substance to attract and hold water molecules from the surrounding environment. This is achieved through either absorption or adsorption with the absorbing or adsorbing material becoming physically 'changed,' somewhat, by an increase in volume, stickiness, or other...
As such, environmental conditions such as humidity
Relative humidity
Relative humidity is a term used to describe the amount of water vapor in a mixture of air and water vapor. It is defined as the partial pressure of water vapor in the air-water mixture, given as a percentage of the saturated vapor pressure under those conditions...
must be kept under control. Pigments add another layer to the problem, forcing a preservationist to fit environmental conditions to two different (and possibly conflicting) sets of ideal limits.
Problems can occur when parchment is exposed to high humidity for a long period of time. For example, collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
in the pages could dissolve and stick together.
These problems are further compounded by the fact that pigments do not dye parchment; instead, they lie on the surface of the parchment and so are rather fragile. Pressing an illuminated manuscript pushes the pigment down, altering the image itself and likely causing damage (such as a relief effect to the other side of the page) so it is very important to not put any pressure upon images on parchment, especially when it is wet. This fact also has to be taken into account when cleaning dirt from the image and when encapsulating or framing illuminated parchment for an exhibition. There must be enough room between the image and the protective surface (such as Perspex) that the image will not be subject to rubbing if the parchment should expand with rising humidity.
Consolidation
Consolidation is a process that can either strengthen the bond between pigment and parchment or add protection to pigments and other finishes from aqueous treatments. Strengthening the bond between pigments and parchment help prevent the pigments from flaking and pulling away. The challenge comes with achieving the best consolidation results while altering the object as little as possible. The material used for consolidation should be appropriate for the pigments, the parchment, and any other aspects that may be affected by the application.Soluble nylon
Nylon
Nylon is a generic designation for a family of synthetic polymers known generically as polyamides, first produced on February 28, 1935, by Wallace Carothers at DuPont's research facility at the DuPont Experimental Station...
was used until the mid-1970s when concerns over the material’s stability emerged. Parchment size was then favored until the mid-1990s when leaf gelatin
Gelatin
Gelatin is a translucent, colorless, brittle , flavorless solid substance, derived from the collagen inside animals' skin and bones. It is commonly used as a gelling agent in food, pharmaceuticals, photography, and cosmetic manufacturing. Substances containing gelatin or functioning in a similar...
gained popularity. This is not to say that gelatin is always the best consolidant to use; no consolidation technique should be used without first considering the pigments and other materials involved, though. For example, gelatin causes white lead to become friable.
Friability
Friability is the ability of a solid substance to be reduced to smaller pieces with little effort. The opposite of friable is indurated....
This problem is compounded by the flexible nature of parchment. One solution to this particular problem is to use some form of a cellulose ether such as methylcellulose
Methylcellulose
Methyl cellulose is a chemical compound derived from cellulose. It is a hydrophilic white powder in pure form and dissolves in cold water, forming a clear viscous solution or gel. It is sold under a variety of trade names and is used as a thickener and emulsifier in various food and cosmetic...
, instead of gelatin. Again, this is not necessarily the right choice for every situation.
There are a few basic requirements for any consolidation agent:
- It has to cause a strong bond to form between the pigment and parchment;
- A strong bond also has to be formed between the layers of pigments and any loose particles;
- There has to be little alteration of the chemicals, including appearance;
- It cannot cause the parchment to lose flexibility.
Ultrasonic mister
One device recently used in consolidation techniques is the ultrasonic mister. Created in 1991 by Stefan Michalski, this device lends itself well to consolidating materials that react badly with liquids. Gelatin is the preferred consolidant.The ultrasonic mister is usually used in conjunction with a paper suction table to direct the mist at the media and prevent distortion
Distortion
A distortion is the alteration of the original shape of an object, image, sound, waveform or other form of information or representation. Distortion is usually unwanted, and often many methods are employed to minimize it in practice...
. This is not the best treatment for illuminated manuscripts that have printing on both sides, though. In this case it is better to forgo the suction table and instead use the lowest setting on the mister and to monitor the process carefully.
Problems may arise if condensed mist falls onto the parchment from the nozzle so it is advisable that the device be placed on the floor or a similarly low level to coax mist to drain back into the mister instead of falling upon the parchment.
Flattening and crease removal
Traditional methods of removing creases and flattening parchment through humidifying have been detrimental to the state of any pigments, causing them to come off the parchment slightly. This is because the parchment and pigments take on and give off moisture at different rates, causing them to expand and contract at varying rates and thus loosening the pigment from the surface. This results in flaking, cupping, and cracking.Gore-Tex
The question becomes whether flattening creased parchment to some extent will cause more or less damage to the image than would be caused by not removing the crease. Sometimes not flattening the parchment in some respect will lead to the further degradation of an image. In these cases some form of hydration is necessary. Due to the nature of pigments, though, it is desirable to avoid direct contact with liquid water. This can be accomplished with Gore-TexGore-Tex
Gore-Tex is a waterproof/breathable fabric, and a registered trademark of W. L. Gore and Associates. It was co-invented by Wilbert L. Gore, Rowena Taylor, and Gore's son, Robert W. Gore. Robert Gore was granted on April 27, 1976, for a porous form of polytetrafluoroethylene with a...
.
Gore-Tex now has controllable pore size and can block out many liquids, including liquid water and many conservation chemicals. Water vapor can still pass through the pores, though, so it is possible to hydrate the parchment and remove a crease without introducing liquid water to the pigmented image. This can be achieved by sandwiching a manuscript in Gore-Tex in varying ways to achieve the desired results.
Mending
Repairing a tear in a parchment with images or text on it is more of a challenge than mending a piece of parchment that does not have any such issues. Care must be taken to not cover up or obscure in any way the image or the text. Materials such as Goldbeater's skinGoldbeater's skin
Goldbeater's skin — the outer membrane of calf's intestine — is a parchment traditionally used in the process of making gold leaf by beating, reducing gold into mere 1μm-thick leaves....
can be made transparent enough to do this but great care still needs to be taken.
Ethics
Above all one question must be continuously asked when working with illuminated manuscripts: will the alterations resulting from this course of action alter the manuscript and, if so, is that change worth the results?Notable preservationists
- Paul N. BanksPaul N. BanksPaul Banks was Conservator and Head of the Conservation Department and Laboratory at the Newberry Library from 1964 to 1981. He left the Newberry Library in 1981 to establish the first United States degree granting program in library preservation at the Columbia University School of Library Science...
- Anthony Cains
- Don Etherington
- Carolyn Horton
- Nicholas Pickwoad
- Roger PowellRoger Powell (bookbinder)Roger Powell OBE was an English bookbinder.Powell was born in London. He was educated at Bedales School, of which his father was co-founder. He served as a signals officer in the Royal Flying Corps in World War I and then became a poultry farmer. In 1930 he began training as a bookbinder at the...
- Abigail B. Quandt
- Peter WatersPeter WatersPeter Waters , former Conservation Officer at the Library of Congress in Washington, DC, USA, worked in the areas of disaster recovery and preparedness, and the salvage of water-damaged paper goods...