Making the mosaics

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12:30pm Eucharist
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Making the mosaics

Mosaics can be defined as pictures that were created using not a brush or pen, but small coloured pieces, called tesserae to create a shape. The technique as such has endless applications and has been known since antiquity. Mosaics are not limited to any particular civilisation or material, but the best-known Western examples today are those created in classical Greece and Rome. Mosaics were also a popular material for floors in Roman Britain as many examples in the City of London and elsewhere testify, including the famous fourth-century Hinton St Mary Floor or a floor excavated on the site of the Bank of England, both now part of the collections of the British Museum.

Early mosaics were floors, made using marble and ceramic material. During the Hellenistic period, artists started using glass to create precious mosaic panels. The naturalism of their mosaics was baffling and became a benchmark for the quality of mosaics.

In contrast, in early Christian times, opaque glass mosaics were used to create seemingly eternal, vibrant decorations for the walls of church. Golden and silver tesserae are created by applying gold and silver leaf to tesserae. The technology behind the creation of opaque glass tesserae, also known as smalti, has remained unchanged since then, but was refined in particular by Italian glass makers. During the second half of the nineteenth century, Venetian kilns were able to offer a range of colours to rival a painter’s palette.

When the Dean and Chapter of St Paul’s Cathedral decided to commission mosaics to decorate the ceilings of the building, the technique had just started to experience a revival in Britain.

Direct and Indirect Method

Mosaics can be set directly and permanently on the area they are intended to cover. This approach, known as the ‘direct method’, has been used since ancient times regardless to material and surface treatment (such as grouting and polishing). Byzantine mosaics were set in this fashion, as they extraordinary cycles preserved in churches in Italy (including mosaics in Venice, Ravenna, Palermo and Monreale) and Turkey (such as the Chora Church/Chora Museum and Hagia Sophia Museum in Istanbul) show. In early modern times, the mosaics of St Peter’s Basilica, Vatican, were created using a version of this method.

In the nineteenth-century another, faster technique emerged which today is known as ‘indirect method’: the mosaic is set on a carrier material in a workshop setting, and then transferred onto the intended surface before being finished. This method is widely in use for large-scale mosaics today. Dtt. Antonio Salviati claimed to have invented it, and developed his own specific approach. His company produced five mosaics for St Paul’s Cathedral in their Venice workshop.

These mosaics were considered too ‘flat’ and dull in their appearance. They also did not take light conditions in the Cathedral into account. William Blake Richmond and Messrs Powell therefore wanted to reconstruct the methods used by Byzantine mosaicists with its ragged, sparkling tesserae surfaces. The technique used for the majority of the panels at St Paul’s is nonetheless not an exact reconstruction of a Byzantine method, in particular since it could be argued that every group of mosaicists is likely to have developed its own distinct method of cutting and setting the opaque glass pieces. It is a unique method, developed and used for this particular mosaic cycle at St Paul’s Cathedral, and was developed as the cycle progressed. The first Richmond mosaics, incl. two Angels holding the Instruments of the Passion (nos 7794, 6431, on the north side of the quire), were set at William Blake Richmond’s Hammersmith House Beavor Lodge, and shipped on the River Thames to St Paul’s. These mosaics use a large number of tesserae, in comparison to the later counterpart on the south side (nos 8565, 7793).