The Mosaic Art Process
Mosaics are created in a number of ways from the classical to several different contemporary methods. I use all of them depending on the materials and the desired effect.
If I want to replicate an ancient Greek, Roman or Byzantine mosaic, or create an original in those styles, I use the double-reverse technique I learned in Ravenna, Italy. For this process I place the design under a mosaic-adhering clear plastic sheet onto which I can place the individual tesserae (pieces) right side up after cutting them with a hammer and hardie. The tesserae can be repositioned as needed at this stage.
The specialty mosaic hammer is sharp and cuts the material placed on the hardie, an upright chisel-like metal imbedded in a wood base. The hammer and hardie are used to cut marble and handmade glass smalti as well as the 24 karat gold tesserae I often use. This hand-cut look cannot be reproduced industrially, so each mosaic is unique. The double-reverse technique is used for wall mosaics, which traditionally are not grouted. The uneven surface and clear interstices between the tesserae give the mosaic their charm and depth.
After setting up the mosaic exactly the way I want it to appear, I glue cheesecloth onto the surface of the mosaic using a traditional hide glue. When that is thoroughly dry (takes several days usually), I turn the mosaic over and remove the plastic and design from the back. The front of the mosaic is tightly adhered to the cheesecloth and is now upside down. At this point I put thin set mortar on the back of the mosaic and attach it to whatever base I am using. When the thin set is dry, I turn the mosaic over and remove the cheesecloth from the face of the mosaic using hot water, to reveal the completed piece.
If a flat surface is desired for a floor, I use the reverse technique. The design is reproduced in reverse on craft paper and the tesserae, cut with the hammer and hardie, are adhered to the paper upside down with a flour-based glue. This ensures that the surface is very flat. Thin set is placed on the base and the mosaic is placed on it paper side up until dry. When the paper is removed it is then grouted as it will be on a floor and needs to be even with no rough edges.
Two other mosaic-making methods involve a direct technique. The pique assiette (French expression for eating off someone else’s plate) style uses broken or cut up ceramics, porcelains and objects embedded directly into thinset on a base. This process looks more finished if grouted.
Alternatively, any kind of mosaic tile, smalti and marble pieces can also be directly adhered to a base with thin set mortar. The disadvantage of this technique is that once the thin set is dry it is difficult and messy to make changes as the mortar is very hard. The advantage is that it is fast and easy and useful if you know exactly how you want each piece placed, or if a certain randomness in design is desirable.
If the mosaic is to be exclusively an interior piece, the thin set mortar can be replaced with a strong glue such as Weldbond. But not gorilla-type glues! A disaster can occur that is irreparable if it foams up too far!
And these are only the main variations on mosaic making. I teach workshops on several of these techniques at the Santa Barbara School of Mosaic Art, www.santabarbaraschoolofmosaicart.com. Take a look at the school site and join us for a fun adventure in mosaic making.