In their quest to achieve just the right ‘look’, artists have experimented with different media. In many cases, they have returned to more traditional paints, often with great success. Here I must cite the example of Andrew Wyeth, whose egg tempera paintings made between about 1940 and his death in 2009 are as brilliant as any painted in the Renaissance. Sadly, as his work is still covered by copyright, I can’t show examples here.

In this article, I look in detail at two failed experiments with novel media: Leonardo da Vinci’s disastrous attempt to use egg tempera on plaster, and William Blake’s glue tempera paintings. In both cases, what we see of these paintings today is but a pale shadow of what the artist originally intended.

Wall paintings go right back to the oldest surviving cave paintings. In ancient times, before the Bronze age, two main techniques were used to paint plastered surfaces: fresco, in which water-based paint is applied to plaster when it’s still wet, and secco, applied to dry plaster. Over many centuries, fresco technique developed into the more reliable, but was also the more challenging for the painter. I have previously explained the technique of fresco in detail. In reality, most large wall paintings classed as being fresco include passages in which paint has been applied to dry plaster.

Raphael’s superb large fresco painting of The School of Athens, painted over the period of 1509-10 in the Vatican Palace, is an example of how well-painted fresco can survive half a millennium. The detail below shows some of the effects that can be achieved in this demanding medium, and how lasting fresco paintings can be.

Despite that, when Leonardo da Vinci painted The Last Supper on the refectory wall of the Convent of Santa Maria delle Grazie in Milan, in 1498, he chose to experiment with a relatively thick paint layer of egg tempera, probably combined with some oil paint. Rather than apply that to a special layer of wet plaster, as in fresco technique, he prepared a chalk ground with glue binder, much the way he might have done for an easel painting.

Leonardo’s choice of media was almost the undoing of this masterpiece. What we see on the refectory wall today is a pale and changed reflection of the magnificent work he painted. Within the artist’s lifetime, it had started to deteriorate visibly, and within sixty years of its completion its paint layer and appearance were in severe distress.

Then followed a period of neglect, in which it deteriorated so badly that it was covered with a curtain, in an attempt to protect it from further damage, which actually accelerated its failure by trapping moisture on the paint layer. In 1726, the first of a succession of misguided attempts to rescue its remains was undertaken. This involved repainting sections using oil paint and varnish, exactly the wrong materials. Another repainting was attempted in 1770, then in 1800 the room was flooded by a storm. The detail below shows its current state, with evidence of some of the cack-handed attempts to repair it.

Compare that with the best record we have of its appearance just over twenty years after completion, in Giampietrino’s full size copy from about 1520, below. Bear in mind that The Last Supper, Raphael’s frescoes, and the oil-on-canvas copy are all roughly the same age.

Leonardo was being innovative in his use of a traditional medium. When William Blake used glue tempera, he was falling back to media that had been largely abandoned over a century earlier.

Glue tempera and distemper are terms used to refer to a water-based paint in which glue is the essential binder. This had been used since antiquity, and that long experience demonstrated its limitations, including:

• ‘Drying light’, a marked colour change occurring as the paint dries, reducing the intensity of chroma.
• Mechanical fragility of the paint layer, making it particularly susceptible to abrasion and cracking.
• Solution on re-wetting, so that glue tempera can easily be reworked like watercolour, but is unsuitable for exposure to water or damp. Hardening of the glue binder isn’t the result of a stable polymerisation, and can readily be reversed.
• Relatively poor protection of light-sensitive pigments, leading to fading of colour over time.

Some artists, such as Joris Hoefnagel, continued to use glue tempera with considerable success as late as 1597, when he painted Diana and Actaeon on vellum, an unusual ground.

A century later, William Blake developed a strong preference for water-based media, and appears to have adopted glue tempera as a more accessible substitute for egg tempera, in which egg yolk is the binder. The two temperas are remarkably different, not least in the structure of the paint layer. In glue tempera, ‘drying’ doesn’t result in a robust polymerised paint layer, as it can always be rewetted and reworked. In egg tempera, drying is rapid and thin paint layers quickly become highly robust and resistant to water.

Blake also appears to have underestimated the importance of the glue used as the binder. Earlier exponents of glue tempera learned to become demanding in the glue they used, an option not available to Blake, who didn’t have a workshop of technicians to prepare his glue, but had to rely on commercial sources. Although a few of his glue tempera paintings have survived relatively unscathed, others have been lost to a grey-brown murk.

This version of Satan Calling Up His Legions from about 1809, now in the Tate in London, was dubbed by Blake “an experiment picture”, and has almost been lost with age.

Blake’s other version, currently at Petworth, is almost identical in its content, and still appears close to the artist’s intent. This may be the result of the specific glue used, and the conditions the painting has been kept in since completion.

This Adoration of the Kings from 1799 shows the dulling of colour and fine cracking from the combination of glue binder on a support of stretched canvas.

The Christ Child Asleep on the Cross, or Our Lady Adoring the Infant Jesus Asleep on the Cross from 1799-1800 is an example that has retained more of his original colour.

Blake’s Virgin and Child in Egypt from 1810 shows the fine modelling he was able to achieve in the figures, using the same combination of glue tempera on canvas. This variation is ascribed to differences in the source and composition of the glue he used as binder, and subsequent care of the painting.

After Blake, glue tempera fell back into obscurity until later in the nineteenth century, when it was revived by movements attempting to return to techniques of the past, most prominently the Nabis in France.

Pierre Bonnard used glue tempera early in his career, when painting this exquisite three-panelled Japoniste screen of The Stork and Four Frogs in about 1889, as the Nabis were forming. Using more modern pigments, Bonnard has achieved high chroma, comparable to anything in oils, and unlike more traditional glue tempera.

Neither of these examples compares with the often catastrophic experimentation with novel media in the twentieth century. Ill-considered choices have since resulted in complete structural failure of paint layers in works of art fetching high prices when sold. Few artists have paid much attention to the craftsmanship of the past, and those who paid millions of dollars for a painting have watched it disintegrate over time, leaving them with only photos of what it originally looked like. Perhaps in some instances that’s well deserved.