Linnaeus) and the web making moth (Tineola bisselliella Hummel). Web making moths lay eggs singly or in small groups within the fibres of the infested material. The eggs are secured to the infested material with a gelatinous excretion. The emerging larvae spin webs consisting of fibres from the infested support and feces. The webbing, often in a tubular form, spreads as the larvae travel across the fabric.
Case making moths have habits similar to the web making moths except that the larva spins a case of silk that is interwoven with fibres removed from the support during feeding, but the case is not attached to the support material. The larvae drag their cases with them and will die if the case is removed.
Vacuuming, freezing, and cleaning are all methods to control moth infestations without fumigants (see Appendix 11: Treating Infestations in Textiles by Freezing).
There are many other insects and rodents that will attack collections. If an infestation is suspected, it is best to try to capture a sample of the pest to determine the most appropriate methods of controlling the infestation.
Rodents
During spring and fall, it is quite common for rodents such as mice, rats, and squirrels to try and find a way into your home. Raccoons and opossums like to find winter refuge in attics, garages, and other outdoor storage structures. Rodents destroy and damage artifacts by feeding on them or using paper and fabrics, especially furniture stuffing, as nesting materials.
Once a rodent has found its way into a space, it tends to return repeatedly. If young are born, they too can return seasonally unless entry is prevented. It is best to store your artifacts within your living space where infestations are less likely to happen and, if rodents do enter, the infestation will be discovered quickly.
CHAPTER 2 Paper, Parchment, and Vellum
Most manuscripts, legal documents, ullic records, diplomas, drawings, and many other two-dimensional artifacts are created on paper, parchment, or vellum. Paper is produced from the pulp of wood; parchment and vellum are made from the un-tanned skin of animals. In the Middle Ages, the term vellum was used to describe fine parchment. Vellum was sometimes dyed a rich purple for very important documents.
Preservation Concerns
The preservation concerns for most two-dimensional works can be divided into:
1. Issues with the support, such as the paper or parchment.
2. Problems with whatever medium was applied to the support, such as ink, charcoal, or pencil. Paper supports are very prone to acid deterioration. Paper is made from cellulose extracted from wood pulp by strong chemicals. The paper produced contains acids left over from the pulping process. Additional acids build up in paper as the lignin in the pulp deteriorates with age, and with exposure to the sulphuric acid that is produced when the moisture in the air contacts sulphur dioxide from coal and petroleum combustion. Art and documents discolour and become brittle as these acids cause deterioration of the molecular structure.
Parchment and other hides are naturally very strong and can withstand a great deal of manipulation due to their composition. During the preparation of hides, alkaline substances are applied making the sheets resistant to acid deterioration. The greatest preservation issues relate to their extreme sensitivity to moisture. Hides often illustrate varying degrees of buckling and deformations due to changes in the relative humidity. This buckling can be so severe that it interferes with the aesthetics of the piece.
Paper, too, can buckle or become deformed due to changes in relative humidity, but the more troublesome risk of exposing paper to high humidity is foxing. Foxing refers to small brown spots that form on paper that can be visually disturbing and result in small holes. It is thought that foxing is a mould growth as a result of impurities in the structure of the paper or the sizing material that was applied to the paper during production.
An exposure to water or 68–70 percent RH will allow mould to attack the sizing applied to the paper, the medium, or the structure of the paper (cellulose), parchment, or vellum. Mould is a health hazard and it disfigures and visually alters artifacts.
Other problems common to paper and parchment supports include discolouration, yellowing, darkening from light exposure, fading, or colour change due to light exposure, darkening due to exposure to acidic materials, matt burn, liquid staining, oil staining (frequently from fingerprints), media-induced staining, adhesive staining, adhesive residue, creases, folds, tears, holes, surface abrasion and fibre loss, pinholes, flyspecks (which appear as dark irregular dots), insect damage, attachment to inadequate or damaging support materials, applied adhesive, or damage as a result of previous inappropriate repairs.
Table 1: Environmental Recommendations for Paper-Based Artifacts
The media used to produce documents and works of art on paper can be just as prone to deterioration as the paper supporting them. Although graphite and pencil are relatively stable, pastels, charcoal, and chalk are all powdery and smudge easily. There are commercially available fixatives, but they should probably be avoided as they can change the colour of the pigments and trap dirt on the surface; some have been linked to deterioration of the paper supports. It is common for twentieth-century blue and black inks of fountain, ballpoint, and felt-tipped pens to fade to a brown colour because the inks were made from dyes rather than pigments. Some of these inks are so unstable they even fade when in dark storage. Older inks also have problems, especially early twentieth-century iron-gall ink. The gallic acid reacts with the iron resulting in corrosion that destroys the paper on which the ink was written. This appears like burns and holes in the paper.
Tempera and other paints applied to a sheet of paper or parchment can begin to flake or powder, resulting in losses from the image layer on the support. When the support, whether paper or parchment, is not handled properly when moved, it flexes and bends causing the more rigid applied media to flake off. Movement in the form of small expansions and contractions also occur when there are changes in the relative humidity. This too results in losses of the applied media.
Specific rules for handling various artifacts are given in Appendix 4: General Rules for Handling and Moving Artifacts and Works of Art, but here are some general guidelines to remember:
• Try not to directly touch the artifacts. The oils occurring naturally on your skin can damage and stain your treasures.
• Handle items with mount and matt boards by the supporting board.
• Handling un-mounted sheets by lifting them by the upper corners so that they hang freely without bending.
• Wear gloves when working with artifacts. White cotton gloves are recommended.
• Always place artifacts on a clean and level surface.
Preventative Conservation
The first step in preservation is to always thoroughly examine your artifact for damage and potential problems and check the overall structural stability of the work. One of the most common and helpful things that can be done at home is a very light, dry surface cleaning to reduce the amount of dust, fibres, and other foreign material that may have collected on the surface. Never attempt
