In order to ensure wooden objects are well cared for, take the following factors into account:
- light, temperature and relative humidity;
- handling techniques;
- modes of storage, display and support; and
- protection from insects, fungi and dirt.
To maintain wooden objects in the best condition, the following environmental conditions are recommended:
- relative humidity levels in the range 40 – 60 %, with a maximum variation of 5 % in any 24 hour period;
- temperature range of 15 – 25 °C with a maximum variation of 4 °C in any 24 hour period; and
- light levels of 50 lux for dyed or painted wood, up to 200 lux for undyed or uncoated wood and a maximum of 300 lux for wooden objects that have largely been used outdoors or have otherwise lost their natural colouring. Keep UV radiation levels at or below 75 µwatts/lumen.
Never place wooden objects in direct contact with outside walls or in areas in which large variations in temperature and relative humidity are expected. Avoid placing wooden objects near fireplaces, heaters, air conditioning vents and doorways. Maintaining relative humidity levels below 65 % should ensure that fungal attack does not occur.
Where both metal and wooden components are present in an object, a compromise may be needed. In these cases, it is preferable to bias conditions in favour of wood as this material is more sensitive to changes in environmental moisture levels.
Never expose furniture and other wooden artefacts to direct sunlight. In addition to causing photochemical damage to the wood itself, veneers and glues are likely to be affected, often resulting in lifting, shrinkage, warping and cracking.
Common sense is the best guide when moving or handling any object. Follow the guidelines below:
- seek help when moving large pieces of furniture;
- plan ahead. Clear the pathway to and the final location for the object and move objects slowly and with care;
- grip objects only in areas that can support their full weight such as the rail of a chair and the apron of a table (not the legs or table top);
- remove any detachable pieces before movement;
- lift furniture clear of the floor when moving it. Otherwise the side thrust on feet or legs can place undue pressure on joints; and
- to reduce the risk of dropping wooden objects, do not use gloves.
Storage and Display
To store, display and support wooden objects safely, follow these guidelines:
- use stable, inert materials for the construction and support of artefacts (see the chapter Preventive Conservation: Agents of Decay);
- the mode of storage is largely determined by the size of the objects themselves - drawers, shelves, cupboards or even the floor itself may be appropriate;
- if drawers are used for storage, enamelled metal drawers are preferred. Wooden drawers may also be used but avoid chipboard and other composition boards;
- store flat objects on level surfaces and use specially constructed supports or padding for objects with irregular surfaces;
- padding, such as polyethylene or polypropylene foam, may be used but only if the object’s stability is not compromised;
- large flat-bottomed objects may be stored on the floor but should be raised on padded blocks to allow for air circulation;
- use dust covers for shelving and keep furniture clean and dust-free;
- do not treat historic furniture which forms part of a collection as furniture. For example, do not sit on the chairs in such a collection;
- be careful what is placed on a piece of furniture as sharp objects may scratch the surface and hot items, condensation or liquid spills can badly affect surface finishes (‘blooming’, staining or even dissolution of the finish);
- maintain a stable, clean environment;
- place bubble wrap and dust covers over large wooden objects;
- do not store or consume food and drink near wooden artefacts; and
- inspect objects regularly, looking for signs of insect attack such as flight holes or frass that may have fallen from such holes. Regular inspection is even more critical for objects which cannot be stored under cover.
Large wooden objects kept outdoors should be placed under cover on a concrete pad to protect them from weathering elements and to prevent easy access by black and white ants. Additional protection from weathering can be attained by maintaining painted or varnished surfaces. Dust these objects regularly.
Use stands to raise wheeled objects from the ground. This takes the weight of the vehicle from the wheels and reduces access by ants.
If transporting wooden objects between regions of differing relative humidity, take precautions to allow the object to acclimatise to its new environment. Packing and equilibration regimes are described elsewhere (see the chapter Handling, Packing and Storage).