Ancient wisdom, modern artistry: The practical value of Roman mosaic rules and principles

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Pictured above: Roman mosaic. Photo in public domain

Lawrence Payne shares the rules of andamento and explains why, even if you decide not to follow them, understanding them is a must for all mosaicists.

By Lawrence Payne

Introducing andamento

The Roman mosaicists were masters of their craft. They created beautiful and intricate mosaics that have stood the test of time. One of the secrets to their success was their understanding of andamento

Andamento is the term used to describe the way that the tesserae (the individual pieces of stone or glass used in a mosaic) are laid. (I use the term “andamento” with caution. Not everyone uses it in the same way, but it will suffice for this discussion.) For Roman mosaicists, it was a set of rules that governed the placement of the lines of tesserae, which were essential for creating a harmonious and visually appealing mosaic without any discordant areas that could pull in the eye to the detriment of the design as a whole. This “point of focus” was something they strived to avoid.

While there are no rules in modern mosaic work, learning about the andamento of Roman mosaics can help modern mosaic artists create more aesthetically pleasing images. By understanding the principles of andamento, artists can learn how to create a sense of harmony, rhythm and movement in their work or, by understanding the negative effect of not using these rules they can purposely create discordant effects. “If you know the rules, then you know how to break them.”

In this article, I will discuss the seven rules, how you can use them to create aesthetically pleasing mosaics and why this is important. I will also discuss how you can learn the rules and, if you feel they are relevant to your style of work, how to apply them in your own mosaics.

A brief history 

After a number of isolated examples that we know of, floor mosaics began to be seen in Greece from about the 5th century BC with pebble mosaics. The big change that concerns us is the beginning of the use of cut stone from the 3rd century BC. This transition to cut stone of the same average size and shape gave rise to the ability to create more precise images with higher levels of detail and the creation of more depth to the geometric designs.

The Greek mosaicists then used progressively smaller tesserae to create the highly detailed “paintings in stone” such as the Alexander Mosaic, which used tesserae that are 1-2mm. When the Romans took over Greece and began emulating their work to produce their own mosaics, they increased the size of the tesserae to 8-12mm. One reason is that they were more interested in creating mosaics that were decorative rather than realistic. They also wanted to create mosaics that were faster to make, and larger tesserae were easier to work with, although the practice of creating some very fine mosaics continued.

There is obviously a lot more to the history but we will now focus on how they set the lines of tesserae in a certain way and why.

So, you have tesserae of the same average size, and you have specific designs but you need consistency in the look of the mosaics. In the same way, you have consistency in the appearance of the architecture of their temples and palaces, their most important structures. Architects used the same range of geometry, proportion, ratio etc for those buildings, Why? Because it makes them look nice! A certain harmony and rhythm in nature and man-made structures is something that we find pleasing. Discordant effects can signal danger, chaos, or disorder. 

The human eye is naturally drawn to patterns and order. When we see something that is consistent and harmonious, it feels pleasing and relaxing. On the other hand, when we see something that is discordant or chaotic, it can feel jarring and uncomfortable.

Every Roman mosaicist applied a set of seven rules in their work although to a much less precise degree than the principles in architecture but with the same goal, to create a piece of work that was harmonious where no one part of the design pulls in the eye to the detriment of the whole.  

The seven rules, three principles and one defining goal

Although the standards of work varied quite dramatically across the Roman world, any mosaicist could apply the following rules to create an aesthetically pleasing mosaic. This would give a consistent approach to the work. 

The three principles are: 

  1. Consistency: This applies to the first two rules about size and spacing of tesserae.
  2. Fluidity: This applies to the middle three rules and refers to the fluidity of the lines
  3. Depth: This principle refers to the final two rules  

You can see how these principles align to the seven rules in Figure 1. The drawings coloured in red are what you want to avoid. 

Figure 1

The seven rules are:

  1. Use the same average size tesserae. Don’t use little fragments to fill gaps that no one will notice anyway.
  2. Ensure that spacing is consistent. Spacing will be set by the individual mosaicist or workshop. If you have small or no spaces, you’ll have a lot more cutting to do. If spaces are too wide, the grout can wear down and the tesserae can start to be kicked up or dislodged.
  3. Borderline is one of the easiest to see in a Roman mosaic. In a design, a diagonal line with a colour change on either side with horizontal lines of tesserae typically requires the use of triangle-shaped cuts on both sides to finish the line creating a “sharp” visual effect. On the other hand, a line without the need for triangle cuts results in a softer, less-defined line. Alternating between sharp and soft lines creates a sense of visual discordance in the mosaic. The placement of a line of tesserae on either side of a borderline pushes the triangle cuts away from the colour change and into the background, and the line will appear softer and less defined. See Figure 2. 
  4. When you have a curved line, don’t fill any gaps created with a triangle shape as it breaks the flow of the line. Instead, open the gap a little more and use a keystone shape, the same as a triangle but with the base cut off. 
  5. Convergence (or “line transition”) is where lines of tesserae of the same colour go into an area of the design that is either widening or narrowing. The lines decrease or increase uniformly until they transition, so the tesserae change the same in their size. What you must avoid in the down transition (e.g. two lines into one) is any of the lines ending in a triangle as a triangle denotes the end of a line.
  6. Offset (or “channel”) the tesserae where the horizontal and vertical lines match up to create a grid-type look. This creates the impression of a very flat, two-dimensional surface. By offsetting the tesserae, it gives it the illusion of greater depth.
  7. Avoid a brick wall effect. If you have rectangular-shaped tesserae, and you set them all with the longest sides top and bottom, then it looks like a brick wall. This appears very flat and has no depth to it, particularly if you’re using modern tesserae (ceramic, porcelain etc) that have what I term a “block” colour, which means there is no shading between the tesserae. This is something that you will only face if you’re using handcut tesserae. With modern, machine-cut square tesserae, it will not be a problem.
Figure 2

This is the “gold standard” of the rules. What you will see in a Roman mosaic can differ to a degree, which is down to the standard of work practiced by any one mosaicist or workshop. This is why I say that it is best to learn these rules by drawing them out. 

Line transition in Palazzo Massimo Alle Terme, Rome (2005). Photo by Steve Richards

Drawing the rules

Drawing lines of tesserae on paper has several benefits. Firstly, it allows you to practice without needing to gather physical materials like tesserae, baseboards and adhesives. Secondly, drawing the tesserae repeatedly helps you improve faster; all you need is a paper and pen and you can practice anywhere. Lastly, you learn to develop your eye, the ability to “see” how many lines of tesserae can fit in a certain area and how much space is left for additional tesserae. By honing your skills in this way, when you come to set tesserae down for your mosaic, you’re doing something you have already practiced many times before.

Borderline in Chilgrove mosaic, Chichester, UK. Photo by Lawrence Payne

In Figure 3, you can see a cartoon car that I have filled in by drawing the lines of tesserae according to my view of how the rules are implemented. You learn not just the rules but also, as you can see in my notes, what makes a good design and how it can be improved.

Figure 3

Applying the rules 

Figure 4 shows what I feel is a good way to process the way the rules are used in going from a single tessera up to setting shapes. It differs slightly from Figure 1 but this is more intuitive to apply. First, you decide on the size of the tessera and then set the spacing you’re most comfortable with and can maintain. This is a single line. Multiple lines mean you need to offset them, and you need curved lines and to introduce keystone cuts. If your lines transition up or down, then you use convergence. Lastly, this gives you the ability to create shapes; this includes figures as they are just a collection of shapes, so you need to think about using borderlines. 

Figure 4

These rules are empowering

In the world of modern mosaics, delving into the ancient wisdom of Roman mosaics with their rules and principles can open up a treasure trove of insights. Hopefully, you will see these rules aren’t just dusty relics of the past but invaluable tools for contemporary mosaic artists. The Roman mosaicists, with their attention to andamento, laid the foundation for creating captivating and harmonious mosaics.

While modern mosaic artistry may not be bound by rigid rules, the knowledge of these principles empowers artists to craft pieces that resonate with a certain rhythm.

Consistency is paramount. The Romans understood the human inclination towards patterns and order, and they harnessed this innate attraction to create their stunning masterpieces. A harmonious mosaic, devoid of discordant elements, avoids creating any point of focus that can pull in the eye to the detriment of seeing the mosaic as a whole.

The ancient Roman mosaicists’ commitment to these principles has left a lasting legacy, and in our exploration of their craft, we’ve unravelled the secrets behind their enduring appeal. Whether you seek to create mosaics that evoke tranquillity or deliberately introduce discordance for artistic effect, understanding these principles empowers you to make informed choices as an artist.

Furthermore, the art of drawing these rules provides invaluable training for the modern mosaicist. It’s a skill-building exercise that sharpens your eye for tesserae placement, rhythm, and overall design. Through practice and experimentation, you can transform your artistic vision into tangible, captivating mosaics.

As we conclude this exploration, let the ancient skills of using those rules and principles infuse your modern mosaic artistry. Embrace the lessons of consistency, fluidity and depth and see much more than a carpet of stones.

About Lawrence Payne
Lawrence Payne began his career in the reproduction of ancient mosaics in 2002 and has completed work for the Museu Biblic in Tarragona, Spain. He also trained and led the team that completed five of the seven mosaics for Villa Ventorum in Somerset, UK.

Instagram: @romanmosaics