Care and Conservation of Archaeological Materials

Care and Conservation of Archaeological Materials
Reproduced with kind permission of the Institute of Conservation (ICON)

Collections of objects housed in museums and in private ownership are normally referred to as ‘archaeological' if they have been found buried in the ground or recovered from under water. They can be of any age, from Stone or Bronze-Age axes to Egyptian ceramics and figurines; Greek or Roman antiquities to cannon-shot and other objects from historic shipwrecks. Community archaeology and the popular hobby of metal-detecting are also producing collections of metal and other ‘finds', and mainstream archaeological excavations and investigations produce thousands of artefacts of many material types every year.
Archaeological objects are collected for different reasons – for their intrinsic interest, age, beauty or value, or because they are clues to the past and have relevance to the place where they were made, used or found. All these objects have some value within society and deserve to be treated with the level of care necessary to conserve them in as unaltered a way as possible. This helps realise their potential to inform, educate and please, both now and in the future.
Objects that have been buried react in a different way...Hardly anything that has lain buried in the ground or on the seabed will have survived unaltered in some way - a combination of physical, chemical and biological factors will have been at work. Organic objects will rot, metals and glass corrode, and salts may build up inside ceramics, stone and other porous materials. An object that appears in good condition may in fact be very fragile; delicate decorated surfaces may be obscured by hard corrosion or concretions; and the ‘chemistry' within the object can often cause continued deterioration if not checked in some way.
Archaeological conservators are expert in understanding processes of deterioration and decay in a wide variety of treatments – they can help identify and analyse most artefacts and materials.
Effects of previous treatmentsYour object may have been ‘treated' in the past – this can be a direct cause of new problems. Using inappropriate chemical cleaners can strip off too much dirt and corrosion, destroying the original surface of the object in the process. Unless it is used in a controlled way and carefully removed after use, a cleaning material can go on acting on an object far into the future. Similarly, the application of oils, waxes and lacquers can do more harm than good by attracting dirt and airborne pollutants to the object's surface, and by sealing in other chemically-active by-products.
Seek advice from a conservator before attempting any ‘treatment' of your artefact. Old treatments may not be visible and can give rise to unpredictable and damaging results.
Handling, packaging, environmentPoor handling and inappropriate packaging present the most common threats to objects, often causing breakage and other physical damage. However, by far the greatest threat is long-term neglect. If unchecked, the effects of a combination of poor environment, inadequate physical protection and chemically unstable packaging materials gradually take their toll. The resulting damage may go unnoticed over a long period of time.
Give your objects the best chance of surviving these threats by following good conservation and collection care practices and seeking professional advice.
What you can do to ‘stop the rot'Most of the actions you need to take to protect your valued objects are comparatively simple, but require a little bit of knowledge. A conservator can give you advice and there are a number of publications and web-based sources that will give you simple instructions (e.g. the Portable Antiquities Scheme). One of the most important steps towards collections care is to assess the condition of your objects as fully as possible, through examination and observation, and to keep a check on them on a regular basis. This will alert you to changes in the object's condition so you can take corrective action.
Here are some basic do's and don'ts:
Keep direct handling of objects to a minimum, and when you do, hold them over a table with a soft covering to avoid loss or breakage.
Use only archival quality ‘acid free' containers and packaging materials. Provide padding to stop objects moving about and to separate items within the same container.
Provide a stable storage environment for metal objects by keeping them in airtight ‘dry' boxes with renewable silica gel sachets and humidity indicator cards.
Avoid attempting to clean corrosion or concretions from archaeological artefacts. Archaeological conservators are trained to have the knowledge, skills and equipment to do this effectively without harming the object. You may – inadvertently – be removing important information.
It is best not to apply waxes or lacquers to any object unless you have taken professional advice beforehand. Incorrect application can do more harm than good.
If attempting to clean dirt from antiquities such as ceramics, marble and stone, test-clean a small area first with warm water and a cotton bud - is there softening or loss from the surface? If it is safe to proceed, a little mild non-ionic detergent may be used. Swab clean areas with small amounts of fresh water and allow to dry slowly and naturally. Do not immerse the whole object in water.
The condition you find your antiquity in is an important part of its history and value. Do not try to ‘restore' your objects to their former complete state by - for example, filling gaps and holes invisibly, or supplying missing parts recycled from other objects. This is at best misleading and, at worst, dishonest.
Keep records of any treatments that you apply to your objects, along with images, measurements, identifying features and, of course, information about where and when you found or acquired the object.
If you are lucky enough to find, or otherwise acquire, freshly excavated archaeological material within the Spain or Castilla la Mancha, you are strongly advised (or required by law) to report your artefact(s) to the relevant authorities in Spain or Castilla la Mancha:
www.mcu.es
www.jccm.es
Guardia civil SEPRONA

Consulting a conservatorAccredited archaeological conservators are highly trained and experienced professionals with the skills and knowledge to assess the needs of any particular artefact or collection and carry out a conservation strategy within a strict code of practice and to a high standard. If you are responsible for the care of an important collection or treasured antiquity, you will find the input of a conservator invaluable in assessing, investigating and treating your artefacts - and providing the necessary levels of care to protect, preserve and enhance the collection.
A conservator can produce a ‘conservation plan'. This will provide you with a condition survey, advice on packaging and storage requirements, the priorities for any urgent remedial work needed to individual objects and identification of longer-term action required. Conservation plans are also invaluable as the basis for a request for grant-aid.
If you want to display your collections, or want to know what research and technical analyses can be undertaken to enhance the information you have about your objects, a conservator can help you do this.
To gain the maximum amount of information from objects that are still in an 'as found' condition, your conservator will provide you with access to specialist skills and facilities such as X-radiography (a low-cost preliminary to corrosion removal and stabilisation of iron objects) and further analysis.
Old collections which have been kept in poor conditions can also benefit from a conservator's input: remedial treatments can prevent further damage and improve the appearance of collections. For example, previous restorations to ceramics and other materials may benefit from reversal and renewing with more appropriate materials and techniques. Conservation costs for accidental breakages and other damage may well be covered by your insurance.

Care and conservation of oil paintings

Care and conservation of oil paintings

Reproduced with kind permission of the Institute of Conservation (ICON)

Paintings and their frames are made of many different materials. These include varnish, paint, glue, canvas, wood, metal, gilding and plaster. Together they form a complex structure that is easily damaged if knocked or dropped. The materials are also sensitive to, and can be damaged by, the surrounding environment, particularly extremes and changes in humidity and heat, as well as by light and dirt (note 1).
How well a painting survives over the years depends on keeping it in a good environment and on sensible handling, storage and display.
What can go wrongPaintings can be damaged in many ways. The canvas might be torn or punctured, or may have split at the edges. The painting might have developed sagging canvas, bulges or dents. If on panel rather than canvas, you may see splits, warps and cracks in the wood; the wood will also be susceptible to insect damage (e.g. wood worm). Even if the underlying material appears sound, you may find that the image itself has areas of cracked, loose or flaking paint, lost paint, or fading. It may have yellow/brown varnish, dirt and dust, whitening, mould or mildew on the surface. Additionally the frame may be in poor condition which places the painting at risk of physical damage.
If you think your painting has a problem or you want to find out more about its condition, contact a paintings conservator. Save any pieces that have fallen off, however small and keep them safely in a bag or envelope as they can nearly always be put back on.
Many of the problems identified above are caused (or made worse) by poor environmental conditions. Most of the materials in a painting respond to changes in relative humidity and temperature by expanding and contracting. If the relative humidity keeps on changing then the painting will expand and contract repeatedly; the structure will become stressed and begin to fall apart. Paint layers may crack, canvas may split, wood may split and paint flake off.
In a museum the environment can be controlled with air conditioning (normally to a relative humidity of 55% (plus or minus 5%) and temperature of 20˚C (plus or minus 3˚C), colder if human comfort is not an issue), but this is not usually an option in the home. In the home, a painting can suffer quite easily from high and low humidity.
Light and dirt can also cause problems. Too much light can fade certain colours and will speed up the darkening of varnish, the more light the faster this happens. Dirt looks unsightly and may be very acid. Acid will speed up the breakdown of canvas and wood making it very brittle and vulnerable to knocks and blows.
A conservator can advise on suitable environmental conditions for your collection, and can monitor the environment and make recommendations if adjustments need to be made.
What you can do to protect your paintingsMoving and handlingTears, holes, scratches and dents are most likely to happen when your painting is off the wall. If you plan ahead when moving paintings, these damages can usually be avoided. For example, plan a move by making sure you have somewhere to put your painting before you move it; ideally when off the wall, paintings should rest face out against a clear wall on a padded surface, away from doorways, furniture and passing people. Always make sure your hands are very clean and dry before moving a painting and make sure the painting is securely fitted into the frame. When carrying your painting, have it facing towards your body and use both hands, one to hold the edge and the other to support it from beneath. Paintings with glass or ornate frames can be heavy, assess whether you need two people before embarking on the move.
Hanging your paintingThink about the positioning of your painting in relation to accidental damage from knocking.
Avoid hanging close to shelves, furniture or where people can knock it.
Avoid hanging behind doors, or in busy corridors where the painting may easily be damaged.
You should also think about the environmental conditions in which your paintings hang. During the summer in Britain, the conditions in a well ventilated room are, in general, fairly good for paintings. However, in winter months, extremes of temperature or relative humidity can cause problems, for example, the central heating in homes really dries out the air and causes problems; whilst rooms that suffer from damp will have high humidity and dampness encourages mould or mildew.
The following points are worth considering when hanging your paintings if you want to take steps to ensure the best possible environmental conditions.
Try to avoid hanging over direct heat or moisture sources, for example, right over fires, radiators, heaters, hot water or central heating pipes; in bathrooms, kitchens or around swimming pools.
Avoid hanging over or next to outdoor vents, or on damp walls.
Avoid hanging in rooms that are well heated in the winter (paintings on wood are the most vulnerable).
Picture lights attached to or near to the top of a painting can get hot and lead to localised heating. It is best to take advice on lighting.
Bear in mind that paintings will build up dirt more quickly in rooms with an open fire or where people smoke.
Think about the security of your painting, and take the following steps to ensure that it is hung safely.
Hanging fitments should be fixed to the sides of the frame, not the top. Choose a thick and solid part of the frame. Make sure screws are secure but do not push them through the front of the frame.
Use good quality picture wire or medium gauge fishing line, run it double and trim off extra lengths.
Attach alarms to backs of frames or backboards, not the back of the canvas or panel.
Conservators can provide advice on methods of lighting that will not cause localised heating; they may also be able to advise on security fittings.
HousekeepingAs with all objects in your home a painting will collect dust and dirt. Dust can be removed using a very soft brush with any metal parts of the brush protected so that they cannot be a cause of damage. Avoid feather dusters and sheep skin dusters, however soft, as they catch. You must be very careful to check that there is no paint flaking before dusting. Do not attempt any dusting if the surface appears unstable.
If your painting is protected by glass this will need cleaning from time to time. Always spray glass cleaner onto the cloth, not the glass. Spray well away from your painting.
The use of backboards is recommended as a preventive conservation measure to protect against the accumulation of dust and dirt, as well as against knocks and accidental damage. A conservator can fit backboards to your paintings for you.
Do not attempt any repair or cleaning yourself. This is a skilled process and should only be carried out by a fully qualified conservator.
Consulting a conservatorThere is much that you as an owner can do in terms of preventive conservation which will slow the deterioration of your painting and protect it from accidental damage. However there are many occasions, particularly those involving interventive treatments, in which the services of a trained paintings conservator are invaluable. Paintings conservators can provide a wide range of services, for example, they can:
Assess the condition of your painting(s) and provide recommendations for the management of a collection.
Assess the environmental conditions in which paintings are hung.
Provide advice on the lighting and hanging of paintings.
Carry out condition reports in preparation for the loan or exhibition of paintings.
Provide advice on preparing paintings for transport.
Carry out technical analysis to inform historical research or conservation treatments.
Carry out treatments such as cleaning and consolidation.
Most local art galleries or museums will provide information about the history of your painting. They may also have regular sessions where you can talk to both curators and conservators. Should you wish to obtain a valuation of your painting, these can normally be obtained from a reputable auction house.
Note 1 This guidance note does not cover miniatures, paintings on glass, vellum, ivory, parchment, single sheet paper or silk, or those works described as works of art on paper such as watercolours, prints, drawings or photographs.