SWAG合集

Summary of applications

We carry out analysis on a wide range of different materials and object types, including, but not exclusively, porcelain, enamels, glass, stone and metals. Our analysis directly addresses questions put by clients, some as basic as characterising the object, for example what it is made of, but most commonly commenting on the date of manufacture of the object. For this we usually use a technique known as relative compositional dating, in which we compare the compositional characteristics of the object with those of secure date and provenance. To do this we use a range of analytical equipment which is capable of giving precise elemental compositions.

Our expertise is in non-invasive and quasi-nondestructive analysis, and we have developed techniques that in many cases allow analyses to be carried out on clients’ premises rather than in the laboratory. Techniques range from surface techniques, from X-ray fluorescence (XRF) and scanning electron microscopy (SEM) to trace element techniques such as laser ablation inductively coupled mass spectrometry (LA-ICPMS).

In addition, we can employ imaging techniques to create three dimensional images of objects using handheld laser scanners and examine internal structures to inform conservation or repair using micro-computed tomography (CT).

We also give advice on absolute dating in cooperation with our external colleagues, with whom we regularly work. Absolute dating of organic materials (paper, wood, shell, pearl etc) using radiocarbon can give a direct date, as can thermoluminescence on ceramics and porcelain. The direct dating methods are often carried out alongside a non-invasive materials survey of the object to ensure the part dated is representative of the whole.

Our services

Free initial consultation

LARA prides itself on excellent customer service and communication. The first stage for most enquiries is to send us an email detailing the object, purported date and question that needs to be answered. A photograph and indication of the size is also useful. We offer a free consultation by email, which includes advice on whether analysis may be able to address the question, what techniques may be employed, whether analysis can be conducted on the client’s premises and an estimate of the cost.

Object testing – art, archaeology or antiques

This service is designed for single or small groups of comparative objects that are historical or archaeological in nature and constructed of any material. Analysis usually takes place over one day in our forensic facility in Oxfordshire. Techniques used depend on the type of material under investigation and questions posed.

Report – a summary report of analytical results is included.

Delivery – reports are sent within four weeks of the analysis date, quicker if required.

High-value object testing – art or antiques

This service is specifically aimed at single, high value art objects or antiques that require detailed scientific and academic research for authentication purposes. The service involves in-depth analysis and provenance research via consultation with an international network of academic partners and institutions.

Report – a detailed report with a study of the analysis of comparable objects is included.

Delivery – reports are sent within 12 weeks of the analysis date, quicker if required.

European porcelain enamel testing

This service is for clients wishing to identify the date of decoration on European porcelain objects of insecure or unknown provenance. By analysing overglaze enamels and areas of gilt decoration with XRF, we can identify typical porcelain pigments dating to the 18th, 19th and 20th centuries. We specialise in Meissen and Vincennes-Sèvres porcelain, and have constructed a comprehensive database of over 500 genuine objects from established collections in the SWAG合集, Germany and the US that we use to compare clients’ objects with. XRF is completely non-invasive, therefore samples are not required. Analyses can be carried out on anything from single objects to whole collections. A verbal identification is provided and can often be given immediately.

Certification/report service – certificates of analysis per object, or reports of analysis by collection, for documentation or sale purposes can be produced on request.

Delivery – certificates are sent within 10 days of the analysis date. Reports are sent within four weeks of the analysis date, quicker if required.

Using the facility

European porcelain

We specialise in dating the decoration of Meissen and Vincennes-Sèvres porcelain on objects of insecure provenance or whose dates are questioned by ceramics specialists. Eighteenth century porcelain produced by Meissen and Sèvres was frequently copied, redecorated or reproduced in the 19th and 20th centuries; the decoration is often of such high quality that it is difficult to identify by eye. An example of this is a group of snuffboxes recently offered for sale at Bonhams, London, many decorated in the 18th century style but some suspected by specialists to be of 19th century decoration. Using our handheld XRF equipment, results showed that a range of enamels were coloured by pigment technologies only developed in the 19th century pigment – key indicators that the decoration on these suspect pieces was of 19th century date or later.

Enamels

Medieval enamels are particularly fine and valuable pieces of artwork, often applied to gilt reliquaries, medals and other objects. However, they were once again extensively copied in the Victorian period, when they came back into fashion. It is often difficult to tell by eye whether a piece is original or a late copy. We have worked extensively on both originals and copies with colleagues from other universities and museums and are able to show that they are compositionally very distinct, differing in both colouring pigments and often in the flux used in the enamel. This means we are usually able to say with confidence whether pieces are medieval or later.

Metals

We work regularly with metal objects, mostly copper alloys, but also precious metals. Analysis can be relatively simple and performed in the clients’ premises. We have access to good databases for both base and precious metals which provide comprehensive dating and provenance information. Our work is often aimed at characterising the material concerned – is it copper, bronze, brass, gunmetal? Each of which can give dating evidence. However, work on museum pieces often concentrates on the nature of inlays and whether all the pieces of object are of the same alloy, giving important information on manufacturing processes.

Glass

We regularly work on glass of all ages for museums and clients. An interesting example is a medieval stained glass window from Canterbury Cathedral, now in a US museum. Using relative dating techniques, we worked from databases of glass compositions to identify both original panels and later repairs to inform conservation treatments on the piece. It is hoped that this will then go back on display in the museum.

Chinese porcelain

We are currently conducting a major forensic science research project with Bonhams auctioneers that is utilising the latest advances in LA-ICPMS technology to identify copies, fakes and forgeries of Chinese porcelain. The research combines the identification of very low abundance trace elements within porcelain glazes and enamels with essentially non-destructive sampling, using an established range of authentic objects to provide the core data.