The use of wax and wax-resin preservatives on English mediaeval wall paintings: rationale and consequences

Abstract

The sixteenth and the nineteenth centuries were the two most critical periods in the history of the conservation of English mediaeval wall paintings: the former because of the wholesale obliteration. of the paintings, the latter because of zealous restoration in a period of pervasive historicism and antiquarianism*. Obliteration of wall paintings under a layer of limewash effectively answered the requirements of the iconoclast and may simultaneously have protected the paintings from subsequent damage. Restoration in the latter period, however, has caused more serious damage. Facilitated by the wealth of empire, the restoration of churches was carried out on a vast scale; in areas where construction was in stone, interiors were usually scraped down to the ashlar and left bare, while in those where rubble construction predominated, newly uncovered paintings were more likely to be retained and treated with a preservative. The preservatives applied during the nineteenth and well into the twentieth century typically contained a wax component and often a natural resin. Although their principal function seems ostensibly to have been consolidation, it is clear from contemporary publications that the provision of an impervious surface, both waterproof and washable, was equally important. Their application seems to have been virtually universal and, furthermore, done as a matter of policy. These coatings have now darkened and the impermeable layer prohibits the movement of moisture, causing an accumulation of soluble salts, resulting in weakening of the rendering and exfoliation. In addition, severely discoloured wax pre~ervatives which effectively obscure paintings have the understandable side-effect of devaluing the painting in the view of those responsible for its care. It is common for dark, flaking murals to be harshly outlined in gleaming white paint (too often emulsion), their boundaries tidied up in imitation of easel paintings, negating their contextual integrity. The removal of these wax preservatives, the repair of the rendering, and the sympathetic reintegration of the murals within their architectural context are the most widespread problems in the conservation of mediaeval wall paintings in England~ Some typical examples are shown in Figures 1-7. One purpose of the present paper is to provide information on the nature of the 'preservatives' the ingredients used, the preparation, and the methods of application. Although in present usage these darkened coatings are grouped under the generic term 'wax preservative', it is clear from the recipes collected in the Appendix that other, equally problematic constituents may be present. Moreover, exposition of the history of the rationale for the confident prescription of effectively irreversible coatings may also have some value. In Keyser's List of Buildings ... having Mural ... Decorations [1], the introductory essay is concluded with a note by Prof. A.H.Church on preserving wall paintings. For 'reviving, fixing and waterproofing', he prescribes the overall application of a mixture of beeswax, copal varnish and spirits of turpentine (Appendix no. 2). This echoes the much earlier