The importance of temperature control for artefact preservation

A look at the major causes of deterioration for museum artefacts, and how these precious items can be preserved for future generations.

Looking down at the little glass case, it may be hard to envision that the item inside could be hundreds, thousands or possibly millions of years old. This item, having been used or made by someone so long ago, still survives today. It may cause you to wonder which everyday objects that we use regularly without much thought may remain long after our time. 

Windows to the past

As windows to the past, memories made real, the preservation of artefacts is of vital importance for the world’s history. It is always heart-breaking to hear that  a museum piece or artwork has been destroyed by natural causes or human interference. While only so much can be done to prevent the latter, museums have an abundance of technology at their disposal. 

The Smithsonian outlines the following major causes of deterioration: 

• Theft and vandalism — self-explanatory, mishandling or purposeful damage to artefacts and art can leave them irreparable
• Physical force — from the obvious force of impact to vibrations and pressure, physical force can damage any museum artefact or artwork. This is why museums display their pieces in cases or behind designated barriers. Of course, this isn’t always foolproof. For example, did you know Michelangelo’s David has a delicate flaw in its ankles? A slight shift in angle, a strong vibration from a train or footfall, or a natural disaster like an earthquake would send David tumbling
• Neglect — forgotten artefacts in storage, poor record keeping, or simply not following process can cause artefacts to succumb to other deterioration factors on the museum’s list, such as…
• Pollutants— gases and dirt can lead to the swift decay of certain artefacts. Chemicals in cleaning can also erode away materials. Even the oils on your hands can be harsh enough to pollute some delicate artefacts
• Water — leaks, floods, and damp wreak havoc on artefacts
• Fire — rather self-explanatory, fire can cause the utter destruction of an artefact, through burning or the resulting smoke damage
• Light — light damage can cause fading or cracking in some artefacts
• Pests — a particular problem in taxidermy specimens or natural materials, pests won’t pause to consider the historical value of a textile before chowing down! 

Perhaps one of the main causes of deterioration, however, is a combination of temperature and humidity. These two elements are noted to be able to accelerate the rate of decay, growth of mould, or warping. 

Without adequate protection, the cost of artefact lost can be immeasurable, monetary value to a loss of any physical record of that item. 

The threat to our heritage

For example, the famous Oxford Dodo holds the title of the most complete single dodo specimen in the world. And yet, all that has survived is the head and a foot thanks to an infestation noted in the specimen around 1755; feather mites are highlighted as the main culprit for devouring the taxidermy dodo’s torso, wings, and feathers. Preservation Equipment advises that a high humidity can encourage fungal growth and pests in natural materials; could better temperature and humidity controls have saved more of the last dodo specimen?

Pests are surely a problem, but the scale and rapidity of temperature and humidity’s effects on a collection cannot be understated. The Telegraph reported how, when the glass roof of the Natural History Museum was cleaned of around 150 years’ worth of dirt, it was quickly discovered that the gathered dirt and the decision to remove the solar reflective film from the glass had had unintended side effects. 

Temperatures in the museum have soared to 40°C and the humidity tumbled, and the artefacts and specimens are already suffering irreversible damage, the article reports. The skin of specimens is cracking and drying, fading as they are sun-bleached, and whale skeletons are also degrading as a result. The museum is not only looking into replacing the solar reflective film, but also at installing a new HVAC (heating, ventilation, and air conditioning) system to try and save the artefacts. 

The problem is not restricted to the UK either — over in Denmark, the country faces losing many historical artefacts due to a rise in damp and mould growing in its museum storage areas, which are reported to lack air conditioning units. CPH Post commented that the museums are using old buildings such as barns or lofts to store the artefacts, which means they aren’t being protected by any level of temperature control. More than 70,000 items are at risk of being destroyed as a result of 118 buildings used for storage being marked as riddled with mould.  

It’s clear that temperature and humidity must be closely monitored, for both artefacts and artwork on display and in storage. The optimum temperature is between 16°C and 20°C— though temperatures as low as 10°C probably won’t cause harm, the risk of condensation grows for anything below 10°C. In terms of humidity, the advised relative humidity is between 40% and 70%, to avoid drying out items or encouraging pest or fungal infestations. It has also been noted that rapid fluctuation in humidity can be problematic. 

(image copyright Herzi Pinki)