How to make a mosaic — the three techniques
There are three primary methods: the direct method, the indirect method and the double indirect method.
The direct method of mosaic construction involves placing (adhering) the individual tesserae into the underlying surface. This method is most suited to surfaces that are not flat and uniform, such as vases. Great examples of this technique can be viewed throughout Europe; mainly wall and ceiling mosaics, drawings and outlines on the walls below were often revealed again when the mosaic falls away.
The direct method best suits small projects that are to be transported. Additional advantages of the direct method are that the resulting mosaic is visible as work progresses, allowing for adjustments to tile placement or color.
A disadvantage of the direct method is that the mosaic artist has to work directly at the chosen surface for long periods of time, this is not very practical, especially for large-scale mosaic projects. In addition, it may be difficult to control the evenness of the finished surface. This is very important when creating a functional work surface such as walls, floors or a table top.
Modern versions of the direct method, sometimes called “double direct,” work directly onto fiberglass mesh. The mosaic can then be built with the design visible on the surface and moved to its final location. Large works can be produced in this way, with parts of the mosaic being separated for shipping and later reassembled for installation. It enables the mosaic artist to work in comfort in a studio rather than at the site of the artwork installation.
The indirect mosaic method is most suited to very large scale projects, projects with repetitive elements or for areas needing site specific shapes. The mosaic tiles are applied face-down to a backing medium (usually paper) using an adhesive, and later transferred onto the final surface such as walls, floors or craft projects. This method can be most useful for extremely large projects as it gives the artist time to rework parts of the design. Mosaic murals, benches and tabletops are just some of the items usually made using the indirect method, as the result is usually a smoother and more even surface.
Double indirect method
The double indirect method is often used when it is important to see the work during the creation process as it will appear when completed. The tesserae are placed face-up on a surface (often adhesive-backed paper, sticky plastic or soft lime or putty) as it will appear when installed. When the mosaic is finished, a similar medium is placed atop it. The piece is then turned over, the original underlying material is carefully removed, and the piece is installed as in the indirect method described above. In comparison to the indirect method, this is a complex system to use and requires great skill on the part of the artist, to avoid damaging the work. The main advantage lies in the possibility of the artist directly controlling the final result of the work, which is important.