Roman Mosaics
Childrens Page (Key Stage 2)
Mosaics - a way of making a floor covering using small pieces of cut stone(tesserae) which are all roughly the same size.
The Greeks began using pebbles to make floor mosaics from about the 5th century BC
The Romans took this method and using cut stone instead of pebbles they created mosaic floors for their villas, bath houses and some office signs were even made as mosaics (Ostia, Port of Rome has examples of very basic black and white mosaics outside of offices).
These images show examples of Roman mosaics
Temples and public areas usually had floors made with the larger cut stone (tiles), a method known as Opus Sectile.
The stones were cut to roughly the same size, 8-12mm using a hammer and hardie (chisel set into a block of wood).
Some mosaics had pieces cut down to 1-2mm for very intricate patterns (for example: the Alexander mosaic, found at Pompeii, Italy).
Using the average 10mm sized tesserae you would need 26 kilos to create 1 square metre of mosaic floor. With 400 tesserae per kilo this works out as 8,000-10,000 pieces per square metre.
All the stone is a natural colour except where you see some shades of red, particularly in Britain (Britannia), and this is where cut brick and tile has been used instead of natural stone.
Patterns were marked on the floor using a sharp tool to etch lines in the dry cement base and also a charcoal wash was used to paint in black lines.
The tesserae were set using a cement called ‘Pozzolan’, lime mixed with ground up volcanic rock. In Britannia instead of the volcanic rock waste material from the inside of a furnace, ground up pottery was used. Again this was mixed with lime to produce a powder which would set when mixed with water. The mosaic floor was rough in texture when completed and so was ground down using pumice stone, sand and water to make it smooth.
Grout – different opinions on this, sometimes used but the tesserae were initially set into the cement up to 2/3rds of their depth. This made them firm enough to grind down as above and the debris from the pumice fills in the gaps.
The floors would then be polished; again we can’t say for sure what with, possibly a linseed oil wax. This works well but would need to be reapplied after washing the floor but if you have plenty of slaves to do it for you that’s fine!
How long would it take? We really don’t know until someone works using the direct method onto the floor. This is setting tesserae directly into the wet cement, no modern methods used. As a guide, using the reverse method, (much faster) I can complete a square metre in 2 days, if all the stone (marble) is already cut. This is for a very simple floor; for complex figural pieces you could be looking at 4-8 weeks for 1 square metre.
The Mosaicists
Little known/written about them, maybe citizens, freedmen but also slaves.
The full process could involve:
1. The Patron, the villa owner who commissions the floor.
2. Pictor Imaginarius, the mosaic painter, the leading artist, who would paint a small size picture of the design for the floor.
3. Pictor Parietarius, scales up the painting to an outline (not a full colour copy) onto the floor.
4. Tessellarius (mosaicist) who actually sets the mosaic.
5. Lapidarius Structor, unskilled worker who prepares and cuts the stone (slave?)
6. Calcis Coctor, unskilled worker who prepares the mortar and other materials. (slave?)
Copyright Lawrence Payne 2010
