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CHAPTER 1 The Home Environment

What are conservation, restoration, and preservation?

Conservation is the examination, stabilization, reconstruction (restoration), and reduction of further deterioration (preservation) of an object. Conservation often includes:

• Scientific analysis of the object and the materials used during fabrication,

• Research into the structure and historic significance of an artifact, and

• Determination of overall condition and stability of the artifact.

Restoration refers to the reconstruction of the aesthetic appearance of an object. This is a small part of the conservation process.

Preservation is another small part of the conservation process that focuses on treatments to retard further deterioration of an object.

The most we are able to do in our homes are preservation and some basic preventative conservation. To preserve the structural stability and to slow deterioration of objects, you must pay attention to the environment, including light, temperature, and relative humidity, as well as the methods of handling, displaying, and storing the object.

Environmental Concerns

Light

All light is a form of energy. When light energy is absorbed by an artifact, it causes chemical changes in the molecular structure of the object. Natural and artificial light can damage objects by fading colours, yellowing varnishes, bleaching paper, and weakening textiles.

For our purposes, the light spectrum can be divided into three parts: infrared, ultraviolet, and visible light. Visible light is the part of the range of light between the ultraviolet and infrared parts of the light spectrum. Ultraviolet (UV) light is invisible. UV light falls beyond the blue portion of visible light. Infrared (IR) is also invisible. It falls just past the red portion of visible light.

Light is measured in foot-candles, lumens, or lux. You can determine an approximation of the number of lux at home using a single lens reflex (SLR) camera or a light meter (see Appendix 3: Using a Camera to Measure Approximate Light Levels).

Ultraviolet light is the most energetic form of light radiation and causes the most damage. To reduce UV damage, it is important to reduce UV exposure. You can do this in three ways:

1. Always use low-UV emitting light sources, such as incandescent bulbs. Tungsten-halogen lamps and fluorescent lamps (both traditional fluorescent tubes and the new energy-saving spiral bulbs) have higher UV output than incandescent bulbs but lower UV than natural daylight.

2. There are UV filters that block the UV from light sources such as fluorescent bulbs and on windows. UV filters come in the form of sleeves that slip over fluorescent tubes and films that can be applied to glass or windows. There are also plastics and glass for framing and display of artifacts with UV reducers incorporated into their structure.

3. Bouncing light off a painted surface will reduce much of the damaging UV energy in natural light.

Diagram 1: Reflecting light — a method of reducing the damage from UV sources

Infrared light (IR) is less damaging than UV because it has less energy, but it is more easily absorbed by the surface of an object. IR may be thought of as heat because it causes an object to warm up, which speeds chemical deterioration. Dark surfaces absorb heat more readily than light surfaces. To reduce heat build-up, avoid direct sunlight and move incandescent bulbs away from artifacts.

Visible light falls between the UV and IR portions of the light spectrum. Light that appears blue is closer to the UV end of the spectrum and is more damaging to artifacts. Examples of blue light sources are cool fluorescent lamps, full-spectrum fluorescent lamps, and sunlight. Warm fluorescent lamps have lower amounts of blue light and incandescent lamps have the lowest amount of blue light. UV filtered sunlight is far more damaging than the visible light emitted from an incandescent lamp. Never use picture lights mounted onto a frame; they are too close to the artifact’s surface. Never use direct spotlights that are closer than three metres to the artifact.

To reduce damage from visible light, you should reduce the amount of daylight and glare from glossy surfaces to produce lower light levels acceptable for viewing. This can be achieved by indirect lighting: either reflecting light off another surface or lighting from an angle. Light damage is cumulative and depends on the intensity of the light level as well as the length of exposure. Rotate light sensitive items that are displayed so that artifacts will have time to “rest” in dark storage.

Temperature

Heat, cold, and cycling of temperatures cause damage to artifacts. When an artifact is warmed, the rate of chemical reactions within the molecular structure increases. These reactions are the deterioration of the artifact. Ambient temperature and exposure to IR light sources such as daylight, incandescent lamps, or spotlights cause warming of an object. Darker objects absorb more energy and warm quicker than lighter surfaces. If an object heats, cools, or cycles through rapid changes of temperature of more than 10 degrees within a short period of time (one to two hours), the result can be significant dimensional change: expansion and contraction.

Relative Humidity

Relative humidity (RH) is a percentage representing the amount of water vapour in the air compared to the total amount of water the air can hold at that temperature. A relative humidity of 100 percent at a given temperature would refer to complete saturation of the air by the water vapour present.

Changes in the RH do not greatly affect most people’s comfort level but a temperature change of a few degrees does make a difference in how comfortable you feel. Art and artifacts react much more to changes in RH than shifts in temperature. It is much more important to stabilize the RH levels than the temperature for the stability and long-term care of objects.

Damage seen at RH 70 percent and above:

• micro-organisms: mould and mildew

• deformations from plane as a result of tension loss

Damage seen at less than 35 percent RH:

• shrinking

• warping

• cracking

• drying out of adhesives

• desiccation

Cycles of RH with changes of more than 5 percent an hour result in expansion and contraction that lead to:

• cracking

• warping

• splitting

• water staining due to condensation

• separation of component layers

• deformations from plane (when an artifact undulates, warps, twists, or distorts causing it no longer to be flat or in its intended shape)

The environment plays an important role in the overall stability and preservation of an artifact. Unfortunately, much structural damage is a result of infestations, poor handling, and human error (see Appendix 4: General Rules for Handling and Moving Artifacts and Works of Art).

Insects and Rodents

Insects

The most common insects found in home collections are the book-lice or paper lice, cockroach, silverfish, firebrats, moths, and carpet and cigarette beetles. It is always best to try and prevent an infestation rather than have to control one, but insects are a common problem. Whenever possible, attempt to use deterrents and mechanical means of controlling an infestation before applying chemicals that could potentially be harmful to the artifacts or humans.

Book-lice (Liposcelidoe) are also known as paper lice. This almost microscopic insect normally lives outdoors feeding on microscopic moulds growing in damp situations. They have no wings but can enter buildings carried on papers, furniture, or boxes that may also be supporting mould growth. Once introduced, book-lice become numerous, especially in the late summer when both the temperature and relative humidity are high. In addition to feeding on mould, they feed on the adhesives in books and wallpaper, as well as cereals and paper products, but do not seem to cause holes as with silverfish and roaches. They are transparent to grey in colour.

Control of an infestation is difficult since book-lice are numerous and easily reintroduced to a collection. Book-lice do not need males for reproduction and can produce up to eight generations a year. Twenty to 90 eggs are laid and hatch in 6 to 21 days. Reduction of humidity will reduce the presence of book-lice.

Cockroaches belong to the insect order Blattaria. Roaches are primarily nocturnal. They breed throughout the year. Eggs are laid in batches of 18 to 50 per capsule and are carried by the female until close to hatching time, about 14 to 30 days. Roaches are able to squeeze through very narrow openings and are good climbers. They feed on books, paper, bindings, adhesives, and any other starchy products. Damage from feeding appears as holes or notches. In addition to the damage caused by chewing, roaches cause a great deal of staining as a result of vomiting, depositing feces, secreting fluid from their abdominal glands, or adhesion of egg casings.

Control of a roach infestation is best done by improved sanitation, minimizing water and condensation, and discarding excess paper and cardboard. When storing artifacts, change wooden storage furniture to stainless steel and, as a deterrent, place paper products in plastic containers rather than paper or cardboard.

If roach infestations recur, you may need to take additional measures. Replace hollow doors with solid core, install insect-proof outlets, store all food products in plastic containers, and seal access between rooms and floors (such as via plumbing and electrical wiring). Non-chemical sticky traps placed directly against the wall near water sources can control an infestation, but fumigation, insecticides, or baits may be required.

Silverfish (Lepisma saccharina) and firebrats (Themobia domestica) have very similar characteristics and feeding habits. The primary difference is that silverfish prefer cool damp conditions and firebrats like hot and humid conditions. The silverfish lays about 100 eggs singly or in groups of twos or threes. Firebrats lay about 50. Adults of both may live two years or longer. Both insects eat carbohydrate and protein-rich foods including fabrics, papers, and adhesives. They particularly like the sizing applied to paper and fabrics during processing. Common evidence of damage includes holes and notches as well as what appears to be scraped or thinned paper.

You can control an infestation mechanically by lowering the ambient temperature. If possible, freezing will kill firebrat nymphs. Using plastic storage containers, reducing the humidity, and increasing light will deter these insects. You may need to use sticky traps, fumigants, or insecticides.

Carpet beetles (several species) and cigarette beetles (Lasioderma serricorne F) are serious threats to books and textiles. It is the beetles’ larvae that cause the most damage to collections as they feed on upholstery, stuffing, dried flowers, fabric, wood, paper, and adhesives.

Dry cleaning or vacuuming infested fabrics, furniture, and books can help control an insect problem. Freezing for 72 hours is a proven method of killing some beetles. Capture a specimen to determine a course of action. Chemical extermination may be required.

The most common clothes moths are the case making moth (Tinea pellionella 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.