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Collection Conservation

Preventive Conservation

 

Works on Paper

Reducing deterioration
Works on paper encompass a wide variety of media – watercolours, prints, drawings, maps, documents, screens and scrolls, to name a few. This range of media is found on many types of paper support. Works on paper will deteriorate at different rates, depending on when they were made and the materials and techniques that were used. However all processes of deterioration are affected by the environment – control of light, heat and humidity levels can significantly slow down the rate of deterioration. Museums and galleries have strictly monitored environments in order to minimise damage to collections.

Inherent instability
A high level of acidity is probably the single most damaging factor for paper. Paper can become acidic for a number of reasons. Prior to the late eighteenth century, paper was usually made from fibres such as linen and utilising processes that resulted in a chemically stable product. However, many papers made after this date are subject to the use of bleaches, loaders, fillers and acidic sizes. In the nineteenth century the inclusion of woodpulp became commonplace. These changes led to the production of paper that were of generally poorer quality. When paper deteriorates there are a number of clear visual signals that indicate problems – typically it may become discoloured, brittle and develop disfiguring brown spot stains, known as foxing. Foxing usually evolves as a result of metallic impurities and micro-organisms in the paper. Sometimes the inks and pigments applied to the paper are acidic, resulting in localised loss or fragmentation of inscriptions or images where the paper is attacked. Acidity can also migrate into a work on paper from poor quality mounting and framing materials. Some of these problems can be dealt with through professional framing and conservation treatment.

The environment

Light
All light causes irreversible damage to works on paper. Natural light and fluorescent light sources are rich in ultra-violet radiation, the most active and damaging part of the spectrum. Sustained exposure to light can cause paper to become brown and brittle; pigments and inks can fade rapidly. The combined effect of darkened paper and dulled image can alter the appearance of a work beyond recognition.

 

Relative humidity and temperature
Excessive levels of heat and moisture in the air can be extremely damaging to works on paper. High humidity and temperature will accelerate the rate of acidic degradation of paper, in addition to encouraging mould growth. In an environment where the humidity and temperature fluctuate dramatically, a cycle of expansion and contraction can be generated in the work o art, causing the support to cockle and the pigments to flake and crack.

 

Dust, insects and pollutants
Insects will thrive in an undisturbed, dusty environment. Paper, together with sizes, adhesives and binders provide an ideal food source for insects. Dust can be abrasive and can retain chemical contaminants, which will degrade works on paper. Airborne pollutants found in city atmospheres compound acidic degradation problems in paper and can engender colour changes and fading in pigments. Unsealed wooden furniture and fresh paint and varnish also emit pollutants.

 

Handling
Paper is easily torn, creased and punctured. A great deal of damage has been caused to works on paper through rough handling and inappropriate repair.

 

Storage
Works on paper should be stored in a clean, cool, dry environment, using archival quality materials. Storage systems depend on the media and whether the works are framed, mounted or loose.

 

Mounting and framing
Poor quality mounting and framing materials become acidic. When works on paper are placed in close proximity to sub-standard materials, acidity will migrate into the paper engendering discolouration, staining and embrittlement. There may also be tonal changes and fading of certain pigments. Fixatives and varnishes are sometimes suggested as a means of sealing the surface of friable media such as pastel, chalk and charcoal drawings on paper. Unfortunately, fixatives cause irreversible texture and colour changes – delicate matte surfaces can become shiny and compacted and colours can take on a harsh, saturated appearance. Tonal balance can be further altered by the darkening effect of the varnishes and fixatives on the paper support. Both fixatives and varnishes will discolour on ageing.

 

Never attempt to treat a damaged work of art on paper yourself. Consult a conservator, who will be happy to provide advice and information.