Shown here is part of the will of John Hawke of Garlinge in the parish of Petham, made 1604 and proved 1606 [ref. PRC/32/41] The scribe used an ink made from the tannic acid of oak galls; growths formed by the tree in reaction to hosting the eggs of gall wasps. Combining tannic acid with iron salts and a binder creates a dark ink which, today, appears purple/brown-black in colour. Many pre‑20th century manuscripts held by Kent Archives are written in this ink – favoured by European scribes for its permanence, water resistance and ease of manufacture. However, iron gall ink becomes acidic over time and can oxidise due to excess iron in the ink formulation, causing weakening of the substrate upon which it has been used. At first, diffused halos develop around written text, followed by the ink striking through the document, leaving a shadowy impression on the verso. Eventually, the ink etches into the substrate to such an extent that material loss occurs, often referred to as lacing.

I is for… #IronGallInk

Made from oak gall tannic acid and iron salts, this ink was favoured by European scribes for over 1400 years owing to its permanence and ease of manufacture. Over time it can deteriorate, causing a type of substrate loss known as lacing.

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Shown here is a researcher wearing nitrile gloves to correctly handle a 19th century albumen print. The card support affixed to the verso provides no margins, subsequently exposing the edges of the photograph to oils, salts and dirt if handled with bare hands. Unless handling items that are chemically sensitive, metallic, or toxic, the use of gloves is largely performative. Often worn in the 19th and early 20th century by those working in heritage settings and the book trade, gloves traditionally conveyed respect for the items being handled whilst also alluding to their value. Much to the frustration of those working in the contemporary heritage sector, this outdated practice is repeatedly portrayed in the media, subsequently reinforcing the public’s mistaken perception that archives should be handled with gloves. Aside from the few exceptions, we handle documents with clean and dry hands, as gloves reduce manual dexterity and hinder the ability to assess fragility through touch.

H is for… #Handling

Wearing gloves whilst handling documents reduces manual dexterity and the ability to assess fragility through touch. Unless items are photographic, metallic or toxic, handling archives with clean and dry hands is generally the best practice.

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Shown here is part of a Lettre de Bourgeoisie – a formal document once issued in certain European regions to grant non-native individuals specific rights and privileges. This example, with blue and gold marginal decoration, was received by Philip Stanhope (2nd Earl) and his son, Charles Stanhope (3rd Earl) from the Republic of Geneva in 1771 [ref. U1590/C709/2] Given the prestige of receiving such rights in a foreign region and the social status of the recipients, this manuscript exemplifies the type of historical document that might feature gilt decoration. Gold embellishments can be achieved in several ways. Methods include applying fine gold leaf over a thin layer of adhesive (flat gilding); affixing gold leaf to a substrate textured with gesso (raised gilding); mixing gold powder with gum arabic to create a gold paint (shell gold); and in bookbinding, impressing heated tools into leather through gold leaf to achieve lettering and ornate decoration (gold tooling).

G is for… #Gilding

The application of gold leaf or powder to the text, margins, bindings and text block edges of important documents. Often used to embellish theological texts and records relating to the nobility to express reverence and emphasise prestige.

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Shown here is a selection of corroded paper fasteners which have been removed from documents at Kent Archives. The harm caused to documents by historical fasteners can be categorised as mechanical damage, such as punctures, pressure and abrasion; and chemical damage, such as staining and embrittlement in the vicinity of a deteriorating fastener due to the formation of metal oxides (e.g. rust) and acidic compounds. Although a preservation concern, it’s thanks to these crusty clasps that many historical records survive in original order — giving present-day researchers a clearer understanding of the context, authenticity, and significance of archive collections. Designed with archival applications in mind, the brass paperclip is our go-to alternative. Coupled with a small piece of folded acid free paper or card to prevent distortion of the document, brass paperclips are safe for long-term use and allow the original arrangement of records to be maintained in a way that is non-invasive.

F is for… #Fasteners

Whilst attached with good intention, these now-corroded clasps – ranging from split pins and staples to bulldog clips – cause mechanical and chemical damage to documents. Our team replaces these with brass paperclips which do not rust.

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Shown here is a certificate awarded to The Whitstable Oyster Company at the International Fisheries Exhibition, 1883 [ref. CAN-U372/X/684] The sheet has significantly yellowed, the crease at its centre has developed into a split and numerous losses have occurred at the margins. The yellowing of paper is largely caused by the oxidation of lignin, an organic substance found in wood which provides structural support and rigidity. The Industrial Revolution made paper more accessible and affordable owing to mass production but with this came greater demand. To meet this, the use of rags as the primary material in paper making was replaced by wood pulp, a readily available but less durable alternative. Exposure to excessive heat, light and low humidity causes the lignin in wood pulp paper to degrade and become acidic, and this weakens the cellulose fibres. Whilst the resulting embrittlement is irreversible, it can be somewhat managed through deacidification treatments and careful storage.

E is for… #Embrittlement

Excessive exposure to heat, light and low humidity can cause a substrate or medium to lose its flexibility, resulting in splitting, crumbling and loss. Commonly observed in paper made from wood pulp owing to its high lignin content.

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Shown here is a white tray containing a document submerged in de-ionised water. It's a small 19th century print undergoing a washing treatment in the Conservation Studio at Kent Archives, Maidstone. Originally neutral, the de-ionised water has had its pH increased with the addition of an alkaline (in this instance, calcium hydroxide) which will help to flush out and neutralise any soluble acidic compounds within the sheet. Such aqueous treatments also reform the hydrogen bonds in the cellulose structure of paper – improving the sheet’s strength and flexibility – and deposit an alkaline reserve which, following the treatment, will remain in the sheet and help to neutralise any future acidity. Conservators also use de-ionised water in vapour form to reduce creases and distortion – a treatment known as humidification – and to hydrate archival-grade adhesives (wheat starch paste, methylcellulose etc.) which are purchased in powdered form and prepared by hand when required.

D is for… #DeionisedWater

Water stripped of metallic and mineral impurities provides conservators with a neutral base which can be conditioned to suit a treatment. For example, an alkaline might be added to deacidify and buffer a document through washing.

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Shown here is an early 19th century town rental on parchment displaying a type of planar distortion known as cockling. Cockling can result in the loss of media (printed or manuscript text, decoration etc.) due to the distorted areas of the substrate being raised and therefore at greater risk of rubbing against anything in the surrounding area (other documents, packaging etc.). Contraction and expansion of the substrate can also destabilise media, resulting in loss. Such distortion of paper and parchment can often be improved or resolved by using controlled humidification to expand the substrate’s fibres, followed by gently drying between blotters with weight applied. Where the media is too unstable to withstand exposure to moisture, a packaging solution may be more suitable to protect the cockled document from abrasion. For example, using a deep mount will ensure there is an adequate gap between the distorted document and its surroundings, preventing any potentially-damaging contact.

C is for… #Cockling

The consequence of a wet document drying unevenly or drying whilst constrained by its surroundings (e.g. an ill-fitting frame). Flattening using a gentle treatment will ensure the surface characteristics of the substrate are preserved.

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Shown here is the reverse side of a map drawn on parchment. At some point, the map has been fixed to a non-archival backing which, if left in place, may adversely affect its preservation. The backing is made from a stiff, 2mm cardboard which has yellowed over time, indicating the presence of acid. The difference in thickness between the parchment and backing has caused the sheet to curl and the resulting creases have attracted dirt due to being slightly raised. A dry treatment technique is appropriate to remove the bulk of the backing. Using a scalpel and other tools, the backing can be gradually scraped away either entirely or, as is more often the case, down to a thin skin. Great care is taken to ensure the document isn't damaged whilst conducting this method of mechanical removal. Following this, a carefully considered aqueous treatment such as humidification, soaking, or applying specialist chemicals (solvents, enzymes etc.) can be used to separate the final layer of backing.

B is for… #BackingRemoval

Non-archival backings can be harmful to documents. Using a scalpel and other tools, backings can be reduced to a thin skin and entirely removed with an aqueous treatment, so long as the media and substrate can withstand moisture.

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Shown here is part of a volume of prints containing scenes of Hastings, Eastbourne, Isle of Wight, Torquay, Llandudno, Whitby and Belgium, 1837-1858 [ref. U929/Z52] The two pages shown are made of pink sugar paper, with an engraving depicting All Saints Church in Hastings affixed to the left-hand page. Having spent a prolonged period of time in direct contact, acid from the engraving ink has transferred to the blank right-hand page, resulting in localised staining. For unbound material, a carefully considered remedial treatment such as washing in deionised water and adding an alkaline reserve could prove effective in reducing this type of staining, so long as the material is deemed stable enough to endure such an intervention. In the case of this volume, the constraints imposed by its binding make it better suited to a non-invasive solution, such as interleaving its pages with sheets of acid-free tissue, paper, or archival plastic to create a barrier against further acid migration.

A is for… #AcidMigration

Acid can transfer between materials that are in direct contact or close proximity, the latter by the movement of acidic vapour. Localised staining can result, as shown here by the impression left on the page facing this engraving.

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Shown here is an image of brightly coloured marbling from the paste-down of a volume held in our collections. Overlayed in the lower-left corner is the Kent Archives logo and below this, a line of text reads 'Conservation A to Z'.

From the challenges we face in preserving our collections to the materials, tools & treatments we employ, discover the terminology of contemporary conservation in Kent Archives' Conservation A to Z.

To learn more, follow the hashtag #KAconservationAtoZ over the coming months! 👀