Agents of Deterioration
These agents can all irreversibly harm philatelic collections.
The magnitude of their inflicted harm is dependent on the inherent properties of the collection materials, and the ways in which the collections are stored.
Relative humitiy (RH) is the measure of how much moisture the air can hold (100% RH = maximum capacity). Temperature and RH are interdependent environmental conditions. Generally as the relative humidity decreases, the temperature will increase. Incorrect or rapidly fluctuating RH and temperatures, are possibly the largest threat to philatelic collections.
Hygroscopic organic materials, like paper, and stamp gum contain moisture. This is referred to as their 'moisture content'. In fluctuating environmental conditions moisture will continually migrate and be re-absorbed, causing the material to swell and shrink; thermodynamic responses known as expansion and contraction. Excessive expansion and contraction causes internal stresses, displacing the materials dynamic equilibrium.
Effect on Paper:
This results in its weakening and distortion; leading to embrittlement and a loss of mechanical strength. The paper ends up feeling stiff, dry, brittle, vulnerable to touch, and discolours yellow/brown.
Effect on Stamp Gum:
This results in ‘gum toning' or ‘tropicalisation' - a yellowed and embrittled polysaccharide craquelure. This process produces acids, which then further encourage paper degredation. All cyclical and avoidable if stored correctly!
Incorrect temperature and humidity can also encourage other agents of deterioration such as pests, moulds or fungi.
Water can damage philatelic collections irreversibly. When you add water to paper, water disrupts the hydrogen bonds of the cellulose, weakening the bonds between the fibres, making the paper softer, delicate, and therefore at increased risk of structural/physical damage.
Water damage can result in:
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Staining and tidelines- through the spreading of soluble deterioration products within the paper
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Distortion- cockling and dimensional change of the paper when drying/dried.
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Solubilization- of fugitive inks and gums causing aesthetic and structural change.
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Delamination- separation of the paper layers.
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Alteration- change in thickness and density through the swelling of the paper fibres.
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Increased vulnerability- of the paper when wet.
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Increased moisture content- resident bound free-water encourages fungal decomposition.
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Deterioration- Accelerated auto-catalytic deterioration of paper.
Fire damage can result in:
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The collections that survives will be:
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Structurally weakened,
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Aesthetically disfigured,
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Damaged from heated gases and airborn particulates
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Parchment items will have gelatinized,
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Seals will be melted and distorted,
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The collections will be water damaged from extinguishers, and
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The collections will be actively deteriorating, because the heat induced by the fire will have catalysed deteriorative reactions within the paper.
Philatelic material is inherently delicate and thus highly susceptible to damage via physical forces (e.g. by careless handling). Mishandling often results in direct damage causing deformation, fracture complete destruction or cumulative fatigue (compromised stress/strain threshold).
For example; Folding and unfolding documents many times will lead to the breakage of paper fibres along the fold lines, and the fracture and deformation, of the document into multiple pieces.
Unfortunately, the more damaged the material, the more vulnerable the material becomes; cyclically becoming more susceptible to further damage by physical forces, and the other agents of deterioration
This process is known as photochemical change. IR is not energetic enough to initiate these reactions, but it produces heat which speeds them up. The rate of photochemical change depends on the object's inherent nature and how much light it has been exposed to. For example, cheap wood-pulp papers containing lignin, like newspapers, are highly sensitive and discolour rapidly when exposed to light.
Photochemical deterioration is cumulative and irreversible. It is immediately recognisable by:
• The yellowing, darkening and discolouration of paper,
• Pigment fading,
• The embrittlement and weakened feel of paper substrates,
• The maturation and embrittlement of stamp gums.
• Low pH of both gums and paper through acid hydrolysis.
Light, is the band of radiation which we can see. Ultraviolet (UV) and infrared radiation (IR) are the invisible bands either side of it. The radiation of light and UV interact with molecules on the paper surface, creating oxidative reactions and acidic radicals.
'Pests' include all micro-organisms, avian, mammalian, insect and parasitic populations. All are attracted to the organic materials that make up philatelic collections; particularly appetizing are paper, leather, cloth, and the carbohydrate based stamp gums.
Rodents, silverfish, carpet beetle larvae, termites and cockroaches are a few of the most predominant species that feed on these organic materials.
If left undisturbed, these pests can do considerable structural and aesthetic damage to valuable collections. Infestation can be a serious problem and immediate pest management is required at the earliest sign. Delay, when dealing with pests, simply allows the infestation to worsen, by giving pests more time to lay eggs, breed and damage material.
Signs of pests include:
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Sightings of live pests
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Carcasses, shed skin and body parts and frass (droppings)
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Piles of dust and detritus (evidence of pest digestion).
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Frass, dross and detritus will act as pest attractors, accelarating insect, parasitic and and microbial attack.
Damaging neighbouring materials include:
Plasticising thermoplastics of stamp albums:
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PVC (polyvinyl chloride)- Acidic, oozes, distorts, discolours, makes inks offset.
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PS (polystyrene)- shrinks, warps, cracks at high temperatures causing physical damage.
Self-adhesive or pressure-sensitive tapes:
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Usually a synthetic, acrylic or modified rubber-based adhesive
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These deteriorate over time and migrate through paper.
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This makes the paper acidic, weakened and severely stained.
Fastenings such as paperclips, staples and rubber bands:
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Cause mechanical damage (creasing, wrinkling etc.)
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Cause chemical damage (rusting, leaching acidic compounds).
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Resulting in brittle paper, tears, accretions, staining and losses.
Mounts, made of unpurified poor quality paper:
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Cause severe 'mount-burn' if mounted under acidic boards
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Cause discolouration and embrittlement of philatelic materials.
Theft in the philatelic arena is relatively common, because stamp collections and philatelic holdings are both portable and negotiable. Whether it is by quick-fingers at philatelic exhibitions, or accidental theft when exchanging items. However unlike in the art-world most of the theft occur simply as crimes of opportunity, rather than by premeditated incident. The result is the physical loss of items which are possibly irreplacable, and correlatively reduced collection value.
Vandalism is also known to occur, but is often accidental; it benefitting neither collector or dealer. Scribble marks, torn covers and other damage caused by the use/trade/study of philatelic items are commonly remedied through conservation.
Dissociation can result in loss of objects, object-related information such as provenance, or the ability to retrieve or associate objects with that information. This commonly occurs if the items are stored in an unorganised manner, without an appropriate labelling system.
Disassociation may lead to a loss in value of items within a collection; reducing the value of the collection as a whole.
