Techniques used in Roman Mosaic Floors
How did the Romans plan and lay their mosaic floors? Using reports from archaeological excavations and practical knowledge we’re going to look at the methods used in ancient times. Other articles cover stone preparation, mortars and adhesives, iconography etc.
The Direct Method
At one site, Villa Arianna, Stabiae, Italy, the mortar holding the tiles (tesserae) in place has eroded away. The tesserae have come off and the guidelines for the mosaic can be seen etched into the floor underneath. The floor was marked out as a grid of squares, each square then had diagonal lines etched going from the corners of the square. This formed a square with 4 triangles in it. To denote straight lines of black tesserae a charcoal wash was used to paint black lines through some of the lines of these squares.
The entire floor was marked out like this and then the mosaicists set the tesserae using parts of the grid. Lines of black tesserae followed the black charcoal lines with lines of white on either side filling a line of the squares.
Other square gridlines were filled (as a square) with either black or white tesserae. Others had the triangles used so in these squares you had 2 black triangles and 2 white triangles, and so on until the whole floor was completed as a geometric black and white pattern.
It makes sense that the men and materials were taken to the villa and the work done insitu. Other guidelines have been found and as modern methods of lifting these ancient mosaics are so much more meticulous then I expect we will see more evidence being unearthed.
Emblemata
This is where mosaics where set onto small panels of mortar or tile and then set into the floor with the rest of the mosaic being set around them. This enables part of the mosaic to be prefabricated. Some of these emblemata were very fine figural scenes while others were quite plain patterns.
In modern times when the mosaic floors have been lifted for removal or conservation it has been possible to spot these areas where emblemata were used due to their base disintegrating faster than the mortar of the setting bed surrounding them.
There you have 2 methods that we have solid archaeological proof for, the method I’ve not mentioned in the Reverse method, i.e. sticking the mosaic tesserae onto cloth, face down and then transporting this to the villa and setting it in place, removing the cloth when the mortar is dry. There is a great deal of controversy over this and I will cover it more fully in another article.
