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Conservation F.A.Qs
How do I clean mould off of my cultural artefacts? Mould can be very damaging to a wide range of objects. Mould grows on organic materials when the relative humidity remains above 65% for a prolonged period. It is disfiguring, can stain and obscure the surface, or even penetrate through the whole structure of an object. To help prevent mould growth, you should try to keep your valuable objects in rooms with low relative humidity and good airflow. Mould growth is most likely to start in corners and in cupboards where there is little air movement. External wall surfaces in a room are also likely problem areas due to condensation of moisture on the colder surface and also through rising dampness evaporating from the surface of the wall in some buildings. Mould can sometimes be found growing on the back of paintings and textiles hanging on external walls due to the trapped moisture. Mould growth may be lessened by ensuring good airflow during humid periods with fans and by opening cupboards. Equipment that draw moisture out of the air can also be installed in a room but only work effectively if the room is kept closed. Likewise, the use of silica gel as a desiccant can only work if sufficient is placed the space to cope with the volume of air and any additional air which entering. In reality, this requires a great deal more than a small bowlfull of silica in a wardrobe-sized space. Prevention of mould is preferable but if mould growth appears it can be cleaned off to some degree. Objects displaying fresh mould growth should first be dried off in a well ventilated area. Sunlight can also be used as the UV light in sunlight may kill some of the mould. Avoid the harshest sunlight in the middle of the day as this could dry and split wood on artefacts or accelerate the fading of dyes on fabrics and watercolour paint There are sprays available in the shops for killing mould. Those that contain ethanol, water and orthophenylphenol can be used on non-painted surfaces. The dry mould can then be brushed off the surface into a vacuum cleaner nozzle. A very soft brush should be found which cannot mark the surface. NB: Killing the mould with sprays or UV light will have only a temporary effect if the artefact is put back into the same unsuitable conditions. There are always mould spores drifting in the air that will colonise suitable environments. Mould is dangerous to your health - always wear a dust mask when dealing with mould growth More information about mould can be found at the Library of Congress Website. What is the best way to hang an Aboriginal bark painting on a wall? With the increase in the collecting of Australian Aboriginal paintings on stringybark, Eucalyptus tetradonta, conservators are often asked how to mount and look after bark paintings. Bark is subject to curling, cracking, splitting and warping when it loses or absorbs water. It is subject to movement when it is placed in environments that are not controlled. This movement can happen over a short or long period of time depending on the rapidity and extent of the environmental change. If a bark painting is constrained or mounted in the wrong way a great deal of damage could occur if movement occurs. In addition, if the paint is not strongly held onto the bark surface, the paint has a tendency to flake off if there is movement. Bark paintings are difficult to mount because of the nature of stringybark and its relationship to water. The following are a variety of ways barks have been mounted and the problems that can arise from the use of such systems:
The Process A method has been developed to fully support the bark. It allows the bark to move in a reversible system that does not employ adhesive contact with the bark. A padded, riveted aluminium framework has been designed to conform to the significant contours of a bark painting. It is held in place at the base by appropriately coloured polyethylene coated aluminium feet and the sides clipped to the system with clear, strong polycarbonate clips. When working through the method it is important to constantly check the system against the bark as small movements during construction can cause frustration in the final alignment if checking has not taken place during manufacture. Barks are generally painted to be hung in the portrait alignment (Thus hung in the vertical, longitudinal direction of the tree growth.) Coincidentally, the bark when moving, does so most radically in the horizontal, or radial, circular, direction of the tree growth. This is very fortunate as the weight can be supported on the longitudinal plane with a heavier gauge aluminium strip. A thinner gauge aluminium conforming to the contours of the bark can support the flexible movement of the bark. Barks requiring hanging in the horizontal direction remain a problem for hanging. At this stage they are mounted as describe above to allow for the horizontal movement, but the feet are placed on the lighter weight aluminium gauge. This to date has not caused any problems. Stress may however occur to the bark of it is very large (over 1 square metre).
Back of bark showing riveted aluminium framework
Cross-section through system showing detail of fixtures on back of bark painting. Conclusion
The above information is a shortened version of a paper that was published by Karen Coote in the Journal of the Scottish Society for Conservation and Restoration in 1995. For a detailed account of the method, e-mail the Materials Conservation Division staff. How do I prevent insects damaging my artworks? Infestation by insect pests is one of the most damaging things that can happen to a collection. A commitment to prevention is the best way to go to ensure its longterm survival. 1. Prevention Physical control - This is the application of screens and seals to doors and windows; careful inspection of all new acquisitions as well as the main collection; and the use of sticky traps to monitor the presence of insects. Cultural control - This is the regular inspection of all items in collections. This includes regular inspection of storage and exhibition spaces along with good housekeeping (keeping all areas clean with no food or drink). Chemical control - This is the careful application of pesticides where necessary. When chemical control is needed, natural pyrethrum and synthetic pyrethoids are usually chosen due to their safety. Checking for Infestations
Blunder traps are very useful as they trap a sample of the insects that are active in the vicinity. The traps are simply a layer of adhesive on a card with a cardboard frame surrounding it. They can be purchased in supermarkets and hardware stores. The traps should be placed around the inside perimeter of the walls, under showcases and behind shelving. The traps can be changed every 6 to 12 months. (If the traps are still sticky there is no need to change them). If insects are found in the blunder traps, they can be identified by yourself, by the entomology departments of state museums or by the CSIRO. If the insects are identified as being a problem, the next step is to find out where the insects are coming from. This may be from outside, through open windows or under doors, behind warm computers, fax/phones, or breeding in an objects such as hair/seed necklaces or feathered headdresses for example. 2. What To Look For On Objects Insects such as cockroaches, moths and silverfish can attack feathers, seeds and human hair string. Obvious evidence can be found by finding eaten sections of the object, live insects, dead insects and insect droppings. Insects are sometimes found in various unseasoned woods used for carving. With green timber, the insect can be already in the wood as it has infested the growing tree. Such items that might have been infested in this way are wood carvings, bark paintings (rare) and seeds. The most common insects to be found are:
3. Treatment of Infestations If an item is found to be infested, it can be put in a sealed plastic bag so other objects are protected. The Australian Museum for example treats all objects as they arrive into the Museum with low oxygen, freezing or nitrogen gas flushing. It does not use any chemical fumigant. Freezing for smaller items (or large ones if a commercial freezer is accessible) seems to be an effective and safe way to handle artifacts that have already been infested by borers. The process will kill borer at all life stages including termites, moths, beetles, their eggs and lavae. It is useful to remember that freezing will kill the infestation but will not prevent further attack. Canvas, seeds, hair, wood, bark, feathers, fibre, leather and textiles can all be treated by freezing, but caution needs to be exercised on items which become brittle with freezing, such as shell, resin and glass. Freezing paintings on canvas is not normally recommended by museums because of the slight potential for the paint to crack. However, if harmful live insects are found, then this is the easiest way to get rid of the problem. The technique described below has been used at the Australian Museum and other institutions for many years. It provides an efficient and inexpensive alternative to toxic fumigants. 1. The object to be treated is bagged in plastic. (Garbage bags will do so long as they do not have any holes in them) 2. As much air as possible is taken out of the bag. 3. The bag is closed with water proof tape or a heat-sealer (if available). 4. The bagged object is then placed in the freezer for 7 days at -20°C. 5. The bagged object is removed from the freezer and allowed to thaw in the bag 6. The object is taken out of the bag a day after it has come out of the freezer. This is to make sure the object has reached room temperature while it is still in a plastic bag. What is the safest way to store textiles? Flat in drawers with lifting sheets. If you need to fold them place a small cushion (cotton filled with dacron) or roll of cotton inside the fold to prevent creases developing with time. Hanging on well-padded coathangers (cotton and dacron or acid -free tissue paper. This takes the strain off the seams and prevents creases developing. Large textiles like tapestries or patchwork quilt covers can be rolled onto a large cardboard or plastic roller. Polypropylene is better than PVC and cardboard should not be the coarse brown type which contains acids. Use tissue or cotton between the layers as you roll it. This will prevent bleeding of the dyes from one layer into the next. Inspect regularly for insect infestation. Silks and wools are particularly vulnerable to several species of moth and beetle. Bag in polythene and freeze for 48 hours any infested material. How do I make a time capsule that will last? Preserving a collection of objects and documents that provide a snapshot of the present for future generations has become increasingly popular. There are a few guidelines that should be followed if you would like your capsule and its content to survive the test of time in prime condition. 1. The contents should be of stable materials that will not self-destruct or cause damage to adjacent materials. For example, black and white photographs will last longer than colour photos; newspapers are printed on poor paper which decays rapidly and should be copied onto archival paper or photographed; some plastic such as PVC are unstable and will decay releasing acidic vapours. 2. The container must be made from a durable material such as stainless steel, glass or polypropylene. The seal on the container must be extremely good and watertight. There is a good document on the Web by the Preservation Department at Iowa State University that contains more information about durable time capsules. (http://www.archival.com/NA12.html) Should I wax or oil wooden objects to stop them cracking? Oils such as linseed oil should not be applied to wooden artefacts as it creates a tacky surface, which will collect dust and build up deposits of hardened oil in the crevices. It also alters the appearance of the surface by darkening it. Linseed oil may help to protect things such as a cricket bat in the harsh outdoor conditions to which it is exposed, but for the longterm preservation of a cultural artefact it is better to control the conditions around rather than using a material which will change its appearance. Likewise, wax polish is appropriate to protect the surface of furniture which is in everyday use, but on many objects it will create a surface gloss that is not in keeping with the original appearance of the item. Oils and waxes may act as buffers against changes in humidity to some extent, but it is preferable to keep the artefacts in the most stable conditions practicable. What can I do with heirlooms and photographs that have been soaked in a flood? Prevent the items from remaining wet too long. You must decide which can be separated and dried with airflow, what should be frozen and what can be rewetted and hung up. Photographic negatives - remove from any paper or plastic folder and rewash in a basin of clean water. They can then be hung up on a string or clothesline indoor and allowed to dry. Photographic prints - treat in the same way as negatives if they are less than 50 years old. Books - If there are only a few wet books, try standing them up with the pages open as much as possible and place in the path of a fan. Wicks made from strips of blotting paper can be placed between the pages to draw the moisture out. If there are too many to treat individually, then freezing may be the option. (See 'Large Quantities section below'.) Glossy paper - Attempt to separate out the sheets while they are still wet. If they are allowed to dry out in contact it will be virtually impossible to separate them without extensive damage to the image. Separation can be attempted very gently in a bath of water by slowly pealing them apart. The water will help to evenly support the paper which is very weak when wet. When lifting out of the water support it evenly and dry on a gauze screen or drying rack. If the paper appears to be in danger of disintegrating when lifted, try lifting it out of the water by sliding a sheet of polythene or other non-stick surface underneath first to act as a lifting sheet. Large Quantities of paper - If you have a lot of books or wet documents, you can bag them in polythene while still wet and put them in a freezer. This way they can either be freeze dried later or taken out in bagfuls and separated and air dried in batches. This way you have a breathing space and can plan the salvage later on, rather than ending up with piles of damp and extremely mouldy paper within a couple of days. For More Information go to the American Institute of Conservation disaster tips. How do I contact a conservator to advise me or carry out treatments in Australia? There are private conservators working in most state capitals. They specialise in different areas generally such as paper, paintings, objects etc. There are a few companies who have a range of specialists. The Australian Institute for the Conservation of Cultural Material (AICCM) have listings of conservators available on the AICCM Homepage. They have also posted their Guidelines for Commissioning Treatment for Cultural Objects on their site which explains the process of choosing the appropriate conservator and the service to expect. If you cannot find the information you require for your area, contact the conservation department of your local museum or art gallery. They are likely to know what is available locally. |
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Here are some of the most frequent conservation enquiries we receive at the Australian Museum. We have given some suggestions for simple solutions, but if in doubt contact a professional conservator. There is information about how to find a conservator in your part of Australia at the end of this page. If you do not to live in Australia check our '
