Making a mosaic floor is a complex project requiring both artistic and technical know-how. It is necessary to use the appropriate material such as tesserae (tiles) made of natural pebbles, marble, granite as well as compatible mortar.
The first and most antique mosaics were floor mosaics. The pioneers of mosaics used simple materials and patterns, mostly geometrical designs but with time this form of art evolved and the art of mosaics bloomed with the use of new materials and colors, allowing for more sophisticated works to be created.
When making a mosaic using the indirect method we start off by designing the mosaic in the workshop before actually cementing the tiles into their final position on the mosaic itself. If we are preparing a mosaic with a multitude of colors we sketch a colored mockup on a scale of 1:10. The selected pattern is then traced on a sheet and we start laying the tiles having first decided on the colors we want to use. As we said before, for floor mosaics we usually choose natural stones, pebbles and colored marble (stones). The necessary tools for this work are nippers and tweezers. The tiles are pasted using water-soluble glue with their bright side against the sheet and rough side facing up.
Once all the tiles are set on the sheet and the first phase of our mosaic preparation is over, we move on to the technical part of the process that is the cementing phase, i.e. the positioning on the floor.
First we prepare the mortar (kourasani) a mixture consisting of quarry sand, Santorini’s soil, powdered marble, lime and water and we apply two coats. The first coat is 2.5 cm thick and this mixture has a coarse texture. It is important to roughen up the surface of the first coat so as to allow adhesion forces to better retain the second layer of 1.5cm thickness, which is fine grained and consists of sifted materials. We must see that this layer is firmly adhered with strong pressure on the lower coat. (image 1.)
Surface preparation is required to make it sufficiently rough, offering this way the best possible adhesion to the mortar on which our mosaic will be set on. After that we carefully turn over the prepared sheet with the tiles on its surface and press them a little way into the adhesive, just enough to allow the kourasani to slide between the tiles and hold them secure.
Then we proceed to connect with the use of the direct technique the different parts of the mosaic on the mortar. This is how we unite the piece we just placed with the preexisting pieces and create a unified mosaic. (image 2.)
When the direct tile laying is completed we moisten the sheet surface to soften the water-soluble glue that kept our tiles together and with great caution we lift the sheet.
The mosaic surface must be rinsed using abundant water and soft sponges to eliminate all traces of the glue used to stick the tiles on the sheet. Once the cleaning is over we proceed to grouting by making a fluid, fine grained grout to which we add color and then pour it on the mosaic to allow it to enter the interstice between the tiles. As soon as it dries we again clean it with water and sponges to have the final result revealed, expressing the rhythm of the mosaic. Then, using the same technique and process we prepare the next section of the mosaic that will be placed alongside the already existing one. At the end of the process we will have created a mosaic floor, resistant to everyday use by people and weather conditions.
An article by visual artist Krystalia Kefallinou , www.psifidota-mosaics,com