Monitoring at Hardwick Hall

Visitors to Hardwick Hall this summer will have seen a rather unusual sight –the Green Velvet Bedroom has been fitted with high-tech equipment to monitor a sixteenth century Flemish tapestry, one of a set depicting the story of Abraham. The monitoring is part of an unusual research project by an interdisciplinary team at the University of Southampton. Researchers from the Textile Conservation Centre have been working with colleagues from the School of Engineering Sciences, in collaboration with the National Trust.

After initial work in the controlled conditions of an engineering laboratory, the team is trialling a technique called digital image correlation (DIC) to measure deformation and strain in tapestries as they hang on display. This technique is used by engineers to monitor strain in structures such as aircraft, but the team is investigating whether it can tell us more about the condition of historic tapestries. DIC works by using computer software to compare pairs of digital images and it is able to identify areas of high strain where damage is likely to happen – the information is displayed in the form of easily interpretable strain maps which identify regions of high and low strain with vividly contrasting colours.

The system is also helping conservators to understand more about the way tapestries respond to changes in temperature and humidity, which could help the National Trust to understand more about how best to control the environment inside its properties. The project is funded by the Arts and Humanities Research Council.

Hardwick Hall PosterClick here to download the poster on display at Hardwick Hall

Tapestry monitoring at Hardwick Hall

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Figure 1. Digital image correlation equipment set up to monitor a tapestry in the Green Velvet Bedroom at Hardwick Hall.

3 strain map super imposed on tapestry

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Figure 2. Part of a tapestry overlaid with a strain map obtained from DIC. Areas of higher strain show up red, while areas of lower strain are blue. The red area is a weak section of silk between two structural joins in the tapestry.

Graph showing the relationship between humidity and tapestry strain

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The work revealed a strong correlation between strain and relative humidity. The graph shows that even small variations in relative humidity can lead to considerable positive to negative strain cycling.