The methods used to conserve leather objects are always under review. Many of the publications that address the conservation of leather are outdated. For this reason, the best way to reduce the risk of leather objects deteriorating is to monitor objects both on display and in storage regularly. The information below is a guide only.
Issues that can occur with historic leather objects
Aged leather can be damaged easily by incorrect treatment. The type of care required to preserve a leather object of historic value is very different from that which was applied when the object was in regular use. In fact, continuing some practices, for example saddle soaping and oiling, on aged leather will actually shorten the lifespan of a historic object made of leather.
Humidity and Temperature – Monitoring and maintaining stable humidity is essential for promoting long-term preservation of leather artefacts. Elevated temperatures and humidity have severe effects on leather artefacts. Temperatures above 20 degrees Celsius (especially when combined with low relative humidity) can dry the leather. High temperatures also accelerate deterioration. High levels of humidity and temperature increase the chance of insect development and mould growth.
Light – Light can fade dyes and pigments on or in leather and, given sufficient time, will break down virtually any organic material. Damage from exposure to light is cumulative and cannot be reversed. Avoid exposing leather objects to direct sunlight, spotlights, fluorescent lights and even bright indirect sunlight for prolonged periods.
Mould – Mould growth can permanently damage leather. It can appear as a white, grey or green powdery residue, or as black spots. When powdery, it can be removed by gently brushing the mould from the object. Cleaning should take place in a well-ventilated area away from other objects to avoid depositing mould spores onto them. A dust mask and vacuum cleaner on low suction should be used during cleaning as some moulds are toxic to humans. Low humidity can suppress mould growth and good air circulation around the object will reduce the chances of new spores occurring. Go to Canadian Conservation Institute resources for further information on how to remove mould from leather.
Insects – There are some insects which find leather very attractive. These include hide beetles, clothes moths and carpet beetles. Objects should be inspected regularly for signs of insect activity, which may include droppings, larval cases, holes in the leather or damaged surfaces, especially on the hidden surfaces of the displayed or stored object. If you find evidence of insect activity, consult a conservator for the best course of treatment.
Improper handling – The greatest danger to leather objects is improper handling, especially using insufficient support when moving or storing it. Thin leather straps and belts, such as a sword belt, are most susceptible. While being moved, objects should be supported on a tray or stiff board that has been covered with acid-free tissue paper. Cotton or nitrile gloves should be worn when handling objects to avoid leaving dirt, oil or perspiration on and in the leather. In storage, the objects should be wrapped in cotton fabric or acid-free tissue paper. Wrapped and padded objects can then be stored in cabinets or acid-free cardboard boxes to exclude light and dust. Storage containers/boxes should not be air-tight in order to allow air flow which will reduce the chance of mould growth. Storage locations should be cool, dry and have good air circulation. If the object is still flexible, it can be padded with acid-free tissue to maintain its shape and provide internal support. Do not overstuff objects in order to try and regain shape if they have already hardened and become brittle. Objects on display should be limited to light exposure and temperature or humidity extremes. Indirect labelling, such as tie-on tags or a fabric label should be used rather than directly marking the leather.
Summary of the care of leather objects
- Regularly monitor objects both on display and in storage
- If in any doubt, consult a professional conservator
- Keep temperature and relative humidity levels stable
- Reduce risk of water damage
- Seek advice from a conservator if there are any signs of pest activity
- Always record what you observe or do
- Avoid displaying leather items in direct sunlight or bright light.
- If the leather is dirty or mouldy, brush – vacuum first and then if necessary, clean it with dry brushes or damp cotton cloths.
- Do not use saddle soap or leather conditioners.
- Do not use petroleum products (or anything that does not list its ingredients) on your leather. Anything that is put on leather is there to stay—beware of creating problems.
- Most leather will stiffen over time; this is generally not a problem, as historic items should not be used. Take time when the leather is pliable to support the item in a displayable manner. For example, lightly stuff the toes of shoes or boots to help them maintain their shape, use acid-free tissue; boot tops can be supported with acid-free tubes made from file folders. Do up all the laces and buckles.
- Likewise, leather cases should be stuffed to hold their shape. If you are opening and closing a case, do not continue to fasten buckles every time; this can lead to breakage.
- The above information does not apply to suede or kid leather; consult a professional for preservation of items made from these types of leather.
Museum of Florida – http://museumoffloridahistory.com/resources/caring/acs4.cfm
University College London – http://www.ucl.ac.uk/~ycrnw3c/JCMS/issue3/dirksen.html
Preservation Australia – http://www.preservationaustralia.com.au/
Canadian Conservation Institute – http://www.cci-icc.gc.ca/resources-ressources/ccinotesicc/8-1_e.pdf
Museums Alaska – http://www.museums.alaska.gov/documents/bulletin_docs/bulletin58.pdf