The Staff 1
The Staff, 1
What is a staff? A staff is a length of wood which can be from 30cm (1") up to 1.5m (5"). Marks on the side correspond with the dimensions of different patterns in a mosaic.
I've detailed different ways to work out a geometric pattern on paper but how would the Romans have followed these patterns when actually laying the tesserae onto the floor? We have very few examples showing how the setting bed was marked out. This is the layer onto which the cement is laid and the tesserae are then pushed in.
Let's take the double strand guilloche border pattern as an example, here is what we want to set out on our floor;
Here is how you work it out on paper;
This is a very simple way to draw out this pattern but if you're faced with bordering a room you could be faced with setting out 100 feet of the same pattern. What do you physically mark on the floor to be able to follow the pattern correctly? You need to be able to keep the proportions correct otherwise the pattern can progressively deteriorate.
Here's an image of a very exact copy of a section of ancient mosaic floor where sections of the mosaic have broken apart showing the guidelines underneath;
You can see where the mosaicists have used a sharp tool to etch lines creating a grid pattern and only parts of this grid are used for each mosaic piece. The black line was a black charcoal wash used to show the borderline.
Clear evidence of them working using the direct method but how often the markings were so extensive is difficult to tell as not many floors have degraded in such a way as to show this. One thing that is clear from this is, it's a very slow method to use. The mosaicist would have used a trowel to place a small amount of cement onto each box and then pushed the tesserae in. As with tilers now there must have been numerous methods in use.
Now lets look at one possible way in which these patterns can be laid out without having to mark the floor so much.
1. You have the pattern you want to set, your assistants cut the tesserae to the same average size for you all the time so the pattern will always have the same basic dimensions. For the double strand guilloche they are the width (A - B x 2) and the space between the single white centre tesserae (A - C).
2. Lay a length of wood, which we will now call a staff, and mark on it the width and length.
3. Place a longer length of wood (batons) down on your floor where you will have the inside of the border, i.e. the side nearest the centre of the room. Then place another next to it and use your staff to ensure these 2 batons pieces are the correct distance apart, the width.
4. On on of the batons use your staff and mark the distance between the centre tesserae (A - C). Do this all the way along baton.
5. You now can spread cement between the 2 batons.
In this image you can see how this works. I've added a length of string along the centre of the border but with this size of pattern you should be able to estimate the centre easily enough. You can see the single white centre tesserae put in place and their position matches the marks on the baton at the top of the image.
It's a simple enough pattern so you really don't need to make any marks on the base which would only slow you down.
The mosaicist may have a variety of staffs all marked up with different patterns. Each staff may have 2 or 3 different patterns marked and these would be essential to his work. The slaves carry the hammer and hardie, the tools, the mosaicist carries only his staffs.
©Lawrence Payne 2013