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Technical Case Study: Richard Ireland’s paint investigation

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Colourful Headfort House

The following text contains extracts from Richard Ireland’s final report concerning the decorative investigation of Headfort House (2008). Microscopic examination of the paint cross-section was carried out by Catherine Hassell.

The discovery of the original paint scheme at Headfort House required a forensic analysis of each room using over 200 cross-sections.

Stair Hall - Centrepiece: secured, showing crackPaint samples were collected and removed from key areas of plasterwork and joinery within the principle rooms during the first phase of the investigation. As a result of these findings the second phase of investigation focused principally on the earliest schemes and in particular the first permanent coloured oil scheme and their relationship to the published original Robert Adam design proposals produced between 1771 and 1775.

Collected samples were first inspected under low magnification, then mounted as cross-sections and viewed under halogen and U.V. fluorescent light to compare the layers. Paint from the coloured layers was dispersed on glass slides and the pigments identified by polarised light microscopy. The identity of naples yellow, and of zinc white and titanium white in some of the later schemes was checked using a scanning electron microscope. A chemical test for lead was carried out on the representative cross sections.

As certain pigments were invented at different known points in the 19th and 20th centuries it is the identification and dating of the actual pigments used rather than the colour they might appear to be which is the value of such investigative techniques.

For example, it was found that the second full scheme for the Eating Parlour utilised chrome yellow in the green which was not invented until 1818 and thus critical to establishing the verdigris scheme as unmolested till the second quarter of the 19th Century.

Supplementary Uncovering

Where viable, the cross-sections were used to guide in situ uncovering of practically all the facets and mouldings of the more strongly coloured schemes. The supplementary uncovering was used as primary evidence where there could be no ambiguity about the relevant layers.

The robust colouring of the verdigris greens used in the Stair Hall and Eating Parlour are particularly suited to determination by uncovering due to the tendency for the dark green verdigris glaze to “bleed” through subsequent coatings over time. This is most readily apparent in the Eating Parlour where frequently deterioration of the overlying paints has been so accelerated as to expose the dark green beneath to the naked eye.

Eating Parlour - East Wall: comparison existing repair & stripped original frame cast

Eating Parlour – East Wall: comparison existing repair & stripped original frame cast

Image to accompany techical case study copy

 

Conclusions and restoration

hh-ep-cent-frame-15-img_3979The remarkable discoveries [that this investigation resulted in] serve to emphasise the pitfalls of cursory archaeological examination and a presumption of how any client has caused their building to be finished. Discussions of the meaning of the scheme is for a wider debate and this [investigation of] the physical treatment only seeks to determine the validity of the painted decoration and set it in its broader context in the development of Headfort by Bective and his family.

Whatever the eventual outcome, Headfort has a remarkable intact suite of five Robert Adam designed rooms with astonishing decoration completed by Lord Bective. Few buildings of such note in Ireland offer such a complete suite of late eighteenth century rooms and singular expression of their owner.

Author: Richard Ireland, 2008