Sometimes when I look at ancient mosaics I fear that I might explode. The beauty of them, the movement, the expressions, the scenes, the patterns, the workmanship, the ancientness, everything about them moves me but I think it might be the use of glass in ancient mosaics which squeezes my heart the hardest; those defiant flashes of colour asserting their presence, like a hand raised in farewell from the deck of a steamer as the ship pulls away.
These dancing, jewel-like fragments appear in all sorts of variations – from almost random embellishments and flourishes to entire mosaics, where glass is used like paint on a canvas: subtle, rich and visually intense. But there’s a mystery here too: since the Romans were renowned for copying designs, techniques and styles of mosaics across their vast empire, why aren’t there more glass mosaics? Everyone must have wanted one. Who wouldn’t? So why do we have so few examples like the drop-dead gorgeous floor mosaic of Zeus and Ganymede from the east of modern day Turkey, now on display at New York’s Metropolitan Museum of Art?
This second century mosaic is so technically accomplished and so detailed that it zims and sings with energy and visual delight.
Could it be that glass of the quality needed to sustain heavy use was relatively rare or only accessible in some areas? It can’t just have been a matter of expense that stopped glass becoming the material of choice because in other aspects of their lives it’s clear that the Romans didn’t shy away from splashing their money around on lavish adornment and serious bling.
As a rule, despite examples like these, glass in ancient (pre-Byzantine) mosaics is confined to a line or two for emphasis or to highlight a particular feature of the design. Look at these strokes of colour in the hair and around the face of this mosaic from the Roman villa of Robacal in Portugal:
Or this flower from Corinth, Greece:
Here, glass is added to pick out the detail of the plant but the background tesserae are stone. As it happens, this floor which measures nine metres by five metres, is unusual for the quantity of glass in its composition. Dating from the 2nd to 3rd century AD and found close to the forum of Ancient Corinth, the mosaic uses glass in it’s border:
And in the decorative details of the main design:
But when it comes to the parts of the floor which would have been under the diners’ couches, the tesserae revert to plainer materials:
Specialists in ancient artefacts often make a great fuss of scarcely visible pigment residues and urge us to remember that the surfaces of statues or temple architecture were once highly decorated and brightly painted. I want to sieze them by the lapels and say: ‘Look! Look down!’ – why bother with a scaly flake of pigment to prove the point when mosaics provide real, glinting, and most of all extant evidence of the Romans’ love of colour?
As for colour preferences, blues and greens are most commonly used but as we see from the Zeus and Ganymede mosaic above, the Romans understood how to use a whole spectrum of strong colours. In mosaics which employ less glass, the material is reserved for details such as peacock feathers and flowing water where the reflective quality of glass would be most effective:
And birds’ plummage in general is also often rendered in glass:
But other details can also be picked out in glass:
More often than not, the use of glass in ancient mosaics is erratic. It might be added to one part of the mosaic composition and then left out in another – why, for example, did the makers of the mosaic above choose to highlight what I assume is a melon on the platter and not the other fruit? Was it because the designer was striving towards realism and green glass is the closest you can get to the right colour? Or was it, as I think is more likely, that glass – or at least the kind of glass which was hard enough to be used in floors – was such a coveted commodity that it was added as an embellishment, enhancing the perceived sophistication of the floor’s commissioner even if an all-glass floor was unachievable?
As one would expect, there are exceptions. Take the 3rd century AD Dionysus mosaic in Cologne’s Roman-Germanic Museum in which glass is used in a consistent and effective way to draw the eye towards particular features of the design – folds of cloth, an urn framed by birds or Ero’s wings as he rides a lion:
Although as a rule the use of glass was limited, there are three places (that I know of) other than in the Zeus and Ganymede mosaic where glass is used extensively: First, the brilliantly coloured wall mosaics of Herculaneum, Pompeii’s sister city which was also buried under the ash of Vesuvius’ erruption:
Second, a floor mosaic which once belonged to a Roman bath house which was recently found in the ancient city of Plotinopolis in north eastern Greece. Here the entire surface, which is still being excavated, is covered in glass tesserae including the borders. Not only is this amount of glass in an ancient floor mosaic extremely rare, the fact that the glass itself is relatively unscathed is also unusual.
Third, are these stunning panels from the border of the 4th century AD Boar Hunt Mosaic which are on display at the National Museum of Roman Art in Merida, Spain. They not only defy the limited use of glass in ancient mosaics rule, but also do it in a most surprising way – by using what looks like glass in the background. [Apologies for not being able to identify the source of the photographs]
It’s also possible that in general glass wasnt extensively used because the mosaics’ makers intuited that the material, albeit brilliant in effect, wouldn’t last as long if subjected to heavy use. Looking at ancient mosaics up close one can see that the areas which once had glass tesserae are often more badly damaged than the parts where stones are used.
Perhaps, too, there are so few examples of ancient mosaics with large amounts of glass tesserae because their beauty made them a natural target? Admired, envied, and desired both at their time of making and through the centuries it would have been tempting to chip out the coloured pieces or try and chisel away a chunk long before techniques for lifting mosaics had been devised or museums prepared to pay for undamaged artefacts had come into existence. So it is mostly only those mosaics which have the lightest sprinkling which survive.
Be that as it may, the Romans started something which later caught on in a big way; during the Byzantine era the use of glass in mosaics soared in popularity. The mosaic masters of the time knew and understood what glass could do – as beautiful as it was on floors, its decorative power was at its most effective on walls or ceilings; they saw how it could catch the light in domed vaults, outline a saint’s features or simply reduce the humble petitioner to a state of awed and subdued respect in the house of God. There was no looking back.
Coming soon: mosaics for special occasions.