Preserving the Archaeological Past

Queensland Museum Antiquities Collection

Queensland Museum holds around 1000 antiquities, mostly from the Mediterranean, including ancient Greek, Roman and Egyptian civilisations and Near Eastern cultures. The collection is very diverse, from small fragments of pottery, iron nails and glass vessels, to large Greek Kraters.

The Museum’s antiquities collection dates from the 1860’s, and is a result of donations from people’s travels, purchases, museum exchanges and early excavations.

The collection is closed today, and we do not currently accept donations of antiquities, due to concerns around the potential illegal collection of objects, in the past and present. The collection is utilised for outreach, education, and display, and we continue to care for the objects by undertaking research and most importantly, preserving them through an active conservation management program for the enjoyment of future generations.

Museum conservation uses scientific principles and an understanding of material properties to ensure the long-term preservation of cultural materials. A wide range of methods and techniques, including interventive treatments, can be applied to preserve the amazing objects held in museum collections.

Conservators undertake many years of specialist training, and are trained to assess material types, object vulnerabilities, and to identify areas of concern, so as to determine the best course of action to conserve an object. Conservators first examine the physical condition of each object using methods such as visible light, UV, infra-red, x-rays, microscopy, chemical analysis, and through analytical techniques such as PXRF and FTIR. They identify areas of deterioration and any past treatments, assess the stability of these areas, and apply new treatments as required.

All treatments and condition information are documented so that the overall condition and history of an object can be tracked across time. Most materials that objects are made from will deteriorate and undergo changes as they age, and as they are subjected to different environmental conditions. Major sources of risk in the environment, including past environments, are improper housing and support, incorrect relative humidity or temperature, excessive light levels, pollution, pests and biological activity, such as mould.

Here are some examples of the kinds of materials in the collection and the conservation techniques used to care for these objects.

Glass

Ancient glass was generally made from melting together sand (silica), a flux (sodium carbonate), and a stabiliser (lime). Glass objects were fashioned from the molten material by moulding, slumping or blowing, and then left to slowly cool and harden.

This Roman 'unguentarium' a small bottle used to hold unguents - ointments, perfumes, balms, and other liquids, used by both men and women. Depending on the skill of the glass maker, various shapes and designs could be created, frequently resulting in very delicate products. This object is part of the Brown Collection - Brown was an English Engineer who worked in Cyprus in the 1800’s.

The unguentarium has been broken into several pieces at some point in the distant past. This is obviously catastrophic but examination of the pieces show us how thin and fine the glass is and demonstrates the skill of its creator. It also reminds us that the object, and others like it, are extremely fragile and not as stable as we might think. Improper handling, shipping and storage can lead to accidental cracking in the fine structure and breakages.

Handling and physical forces are the major source of damage for this type of object. We have chosen not to repair the unguentarium as the pieces are a useful device that demonstrates the skill and craftmanship of the Roman artisans.

two photographs of a pale yellow brown glass candlestick including a view of broken glass fragments — Roman ‘candlestick’ unguentarium, Italy 1st-3rd century CE.
Image: Peter Waddington, Queensland Museum.

Ceramics

Ceramics are any kind of object that is made of clay and hardened by heat, either at low or high temperatures. Ceramics are often decorated by carved lines and incised patterns, or through the application of slips and glazes to colour the surface. The final colour of a ceramic can be manipulated by altering the atmosphere inside the kiln.

Ancient Greek artists perfected this and used a slip and a three-phase firing technique to produce the red and black colouration seen below. The museum collection contains a few key examples of Greek pottery vessels. This amphora is a storage jar of large capacity for holding wine, water, olive oil or dry goods. This type of vessel was often decorated with scenes from daily life or with mythological subjects.

The amphora is attributed to the Varrese Painter, who was a prolific artist of his time and had considerable influence not only on his immediate followers but on other master artists of the ancient world. Only around 200 vessels of his are known to exist today, and so we are incredibly fortunate to care for one in the collection.

When assessing these kinds of items for display conservators thoroughly examine the surface to identify any cracks or repairs and determine if the object is stable.

Are the cracks new or old? Are they stable? Have they been repaired? Are the repairs stable, and are they aligned? Do the repairs need to be reversed and redone completely, or added to, or disguised? What adhesives should be used and how will it be applied?

This object has quite a few areas of damage, and extensive historical repairs, as can be seen in the image below. Sometimes these repairs are really obvious, but sometimes you need an eagle eye!

Table amphora, Apulia, Italy, circa 360 BCE-330 BCE.
Image: Peter Waddington, Queensland Museum.

detailed view showing the cracks in an amphora storage jar from the museum collection — Detailed view of a Table amphora, Apulia, Italy, circa 360 BCE-330 BCE, showing signs of cracks and repair.
Image: Peter Waddington, Queensland Museum.

Organics – wood and plant fibres

Organics, such as wood, plant fibre, papyrus and textiles, are amongst the most vulnerable material types. Consequently, organic objects from ancient times have rarely survived. Organics are subject to many different kinds of deterioration which can result in changes in colour (such as discolouration or fading), embrittlement (including cracking and distortion), and loss (through rotting, pest activity or breakage).

This hawk statue is from Ancient Egypt and was found in an Egyptian tomb. It was originally brightly painted and over time it has lost most of its decorative pigment - only slight traces of black pigment remain around the eyes and traces of red pigment on the body. It is interesting in a way to see the wood that this object was carved from and the artists hand, now that the pigment is largely lost.

The children’s toy ball is another object which demonstrates ancient hand techniques and is made from plant fibre wrapped onto itself. Often wooden objects and plant fibre do not preserve very well as they are highly susceptible to poor environments (in particular humidity changes) and biological attack (insects, mould and other pests).

Both objects were found in tombs which tend to be enclosed and secure, dry spaces that help preserve organic materials, however, tombs weren’t completely safe. As you can see the children’s ball has numerous holes indicating that it has suffered damage by insects, such as dermestid beetles, which were present in ancient Egyptian tombs.

collection photograph of a carved wooden sculpture in the shape of a hawk — Egyptian wooden hawk, Sokar-Osiris, Late Period 664-305 BCE.
Image: Peter Waddington, Queensland Museum.

collection object photograph of an ancient Egyptian woven fibre ball of plaited palm leaves against a white backdrop — Egyptian Fibre ball, New Kingdom, 1550 BCE-1069 BCE.
Image: Peter Waddington, Queensland Museum.

Metals

A variety of metals, metal plate and finishes can be found in museum collections. Many of these are susceptible to corrosion reactions, which are governed by their chemical composition, grain structure and physical environment. While the extent of deterioration will vary depending on the metal, metal and given the same environment one metal may deteriorate faster than another, in general metals do not survive well in burial conditions, like soil.

The vast majority of metals in the antiquities collection are made from bronze or iron. Iron nails of all sizes were made by hand by the Roman legion's blacksmiths in their workshops (fabrica). Yet the humble nail represents a significant labour investment and highly developed industry – from mining the rock, preparing the ore, collecting fuel for processing, building furnaces, and smelting the iron, all before the nails could be forged.

Roman nails tend to have a square tapered shaft with a large head and as such are easy to produce quickly and en masse. Nails were used for a multitude of purposes – in building fortifications, walls and gates, as well as in legionary fortress buildings. The larger nails were used to hold the wooden stockade around the fort in place. They were also used to bind the timber roofing of the fort buildings.

Metals, and in particular iron, can be difficult to treat due to the nature of the corrosion products. Iron will corrode in the presence of oxygen and water, forming a porous crust on the surface. This corrosion process is made worse by the presence of salts found in burial conditions

Bronze disease is another common issue for antiquity collections and also occurs due to salts in the soil. In this case the salts react with the copper in bronze objects to form copper chloride, and is often seen as a light green surface powder. Treating this type of corrosion involves a toxic chemical, and as such, conservators are very cognizant about health and safety. Halting corrosion completely in objects from burial sites is very difficult and sometimes items need to be retreated many times.

Conservators often use preventive techniques, such as manipulating the environment, to avoid continued use of chemicals and the retreatment of objects. At the museum, metals in the antiquity collection are stored in a low humidity microclimate – metal drawers with acrylic lids and silicone seals. The low humidity is achieved using desiccants, such as silica gel or bentonite clay, which helps to reduce the deterioration rate while they are in storage, given that most items spend a lot longer in storage than out! The see-through lids also allow access and inspection without exposing items to higher humidities and eliminates the need for handling.