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Was and sealing was seals
The passing of time has always impacted on all types of artefacts. Changes can be age-related and due to different causes of decay, being particularly evident in very old items.
Seals present two types of decay. One is determined by physical and mechanical causes and is present in all seals no matter what material they are made of, while the other is caused by the chemicals contained in the materials the seals are made of.
Seals can be severely damaged by what can be called exogenous reasons, i.e. caused by external factors, or endogenous reasons related to the way the artefacts were made.
Wax is sufficiently stable from a chemical point of view, though unsuitable conditions of temperature, humidity and light can determine structural changes.
Generally speaking, changes in environmental conditions during the construction and conservation of seals reveal how some of these exemplars, in particular beeswax seals, are often fragile, not coherent or present more or less aggregated flaking, and even pulverisation.
Intervention on sealing wax items is less articulated thanks to the very structure of the material.
In addition to its fragility resulting from its attachment to writing supports, this material is particularly susceptible to very alkaline solutions and tends to dissolve in the presence of alcohol-based substances. Hence, it is clear that great care must be taken when paper and seals come into contact with wet cleaning solutions (washing, deacidifying treatments, etc.).
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In our laboratory we apply a restoration wax, in other words a specially prepared mixture made up of exact amounts of whitened and depurated beeswax, Dammar resin and carnauba. The first ingredient of this restoration waxalmost matches the material nature of the seals, while from a chemical point of view resin is one of the original components of the seal and is added to enhance elasticity and facilitate manufacturing. The third ingredient, carnauba, is used to convey greater resistance and compactness to the amalgam.
Finally, a vegetal or mineral pigment is added to this restoration wax in order to adjust it to match the colour of each original seal. Care is taken to give the restoration wax a slightly different hue to highlight the restored portion.
In other laboratories the waxes are generally taken from pre-prepared samples with very few alternative options.
Cleaning the surfaces
When restoring seals, the first and certainly most important step is to clean the seal surfaces. This step must be as non- invasive and as effective as possible, and has to remove the superficial deposits and restore the original seal image. Great care is required as the operation in irreversible. Two types of interventions are used, either dry cleaning or a method using solvents, also called wet cleaning. In both treatments electron microscopes are used to detect the areas at risk and perform interventions with maximum care.
In our laboratory wet cleaning treatments mainly use water-based solutions and only rarely utilise organic solvents. Expert know-how and maximum care are required to carry out this delicate operation without wetting the cord fibres attached to the document as they would absorb the damp and it would spread along them.
Cleaning is performed in diverse steps over a long period of time in order to observe the reactions of the wax surfaces after they are completely dry.
The cleaning of applied sealing wax seals is less complicated than beeswax seal cleaning procedures, and in the former dry cleaning with soft-bristle brushes usually removes the dusts.
Structural consolidation
The aim of interventions on flaking beeswax seals is to restore coherence to the material and allow the impression to be consulted without the risk of losing any information.
Seals that do not present flaking often require only consolidation interventions. As they often appear as simple fragments, and are not infrequently precariously attached to the document they belong to, two types of interventions are foreseen. One is to consolidate the seals generally along their edges, while the other more extensive procedure generally consists of replacing missing parts. The decision hinges on a series of planned assessments of the jeopardised areas of the seals carried out prior to consolidation.
Replacing missing parts
When the seal is in fragments and simple consolidation is not able to restore effective consolidation, we consider the possibility of recreating some of the missing pieces.
Replacing missing pieces is always functional to seal consolidation, especially when a very thin impression requires a more resistant supporting structure and when many fragments have to be joined together.
The reconstructed missing parts will always be some millimetres thinner than the original seal to highlight the intervention and allow clear visual and structural comparison of the two materials.
Joining up fragments
In addition to the afore-mentioned consolidation and replacement procedures, the fragments of wax seals have to be joined up to recreate a single item.
In some cases we prefer to adopt a particular technique using “transparent polycarbonate” that we were the first to experiment. As a rule, we do not use adhesive substances to join up the fragments as they tend to emphasise the fracture line and, moreover, do not always combine durability and reversibility.
As previously mentioned, our laboratory uses the same restoration procedures for wax and sealing seals.
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