MOSAICING A CURVED LINE OF TESSERAE.

The same is true when mosaicing a curved line - if you try to leave a right angle to the curve each time, then it all becomes much easier. Not surprisingly, what you end up with are a series of wedges that steer themselves around the curve.

INDIRECT MOSAIC

When you buy a sheet of mosaic tiles, you will see that the tiles are spaced apart on the backing paper, the gap allowing for the finished grouting when being used for swimming pools. The reverse
of the tiles (the face not attached to the paper) are 'ribbed' to allow cement to be buttered to them to 'key' them so that they can be applied to the rendered wall. When dry, the backing paper can be soaked off and the tiles grouted. This is the basic principle of an indirect mosaic.
   When a flat surface is required, such as a floor, a tabletop, a swimming pool or a work surface, the mosaic needs to be made indirect. An indirect mosaic is one where the tesserae (vitreous, smalti, or whatever material you are using) have been laid face down onto paper using a water-soluble adhesive. Because the surface of the paper is flat, the resultant surface of the mosaic will also be flat. Working indirect also means that if working on, say, a swimming pool, the mosaic artist can work
in their studio instead of having to travel to be 'on site'. If you wish, you can cement the papered mosaic to a board and then stick it to a wall (see the Frog Splashback).
  When set into cement or concrete, an indirect mosaic is suitable for external use and will last not only a lifetime, but if the Roman mosaics are anything to go by,for centuries to come.
  Incidentally, there is much debate as to whether the Romans worked indirect or direct. In my opinion, the very reason why Roman mosaics were designed around 'emblemata' (circular pictures in the centre of a larger area containing a background and border) is precisely so that the master
mosaicist could work comfortably in a studio on the indirect insertion, whilst the poor apprentices battled it out on their hands and knees working in the direct method on site.

WAXING A BOARD FOR AN INDIRECT MOSAIC.

I once had the embarassing experience of delivering a series of mosaics half way across the country only to find that I couldn't remove the paper from the board! Because I had worked

HELPFUL HINTS WHEN WORKING DIRECT

• Use 12 mm (1/2 in) plywood for boards up to 60 cm (2 ft) square, 2 cm (3/4 in) if larger. Better still, use Medite MDF which is the most expensive brand because it contains the highest percentage of resin and therefore doesn't wrap in normal conditions. I use 16 mm (5/8 in) MDF because it allows one to frame the mosaic with 2 cm (3/4 in) long vitreous tiles.
• Make sure that the tesserae are placed with their flat side uppermost, particularly when rubbled to less than 1 cm (3/8 in) square. If you are using ceramic Cinca tesserae then this is not a problem as both sides are flat. You can use this fact to your advantage and flip over the shapes, if necessary, in order to fit them in.

on them slowly over a period of time, the wallpaper paste had soaked through the stretched paper and adhered to the board. There was no alternative but to return home and spend the following week transferring the mosaic, piece-by-

HELPFUL HINTS WHEN WORKING INDIRECT

• If the mosaic is a large one and will need to be cut into pieces, draw a series of horizontal and vertical wavy lines on the back of the paper. These will later act as registration marks.
• Always use a water-soluble glue; wallpaper paste is ideal.
• Remember to place the tesserae flat side down, if using a mirror this means silver side up. When placing the tesserae, allow slightly larger interstices between them to allow for paper shrinkage. If you need to cut the mosaic into sections, remember to allow a big enough gap to drive a scalpel through the paper between the tesserae.

piece, to a board which had beeswax rubbed into the area where the mosaic was to go. Needless to say, I now only use waxed boards.
  To wax a board, draw a line 5 cm (2 in) all round from the edge of the board. Rub beeswax into this internal area (you can make do with rubbing a candle over it if you wish). Only wax the 'mosaic image' area; the surround needs to be kept wax-free so that the gummed paper tape will sick to it. You
are now ready to stretch your paper.

STRETCHING A SHEET OF PAPER

The sort of paper that is ideal for stretching is the thick brown craft paper sold in stationer's shops. The paper has a smooth side and a ribbed side. Although it is largely a matter of choice, I prefer to lay the ribbed side of the wrapping paper uppermost so that the tesserae 'key' to the paper better.
  Cut the paper 2.5 cm (1 in) larger all round than the waxed mosaic area that you are about to work (see Roman paving slab). Then tear off four lengths of 5 cm (2 in) wide gummed paper strips from a roll that can also be purchased from your local stationery supplier.
  Wet the wrapping paper by running it through a bath of cold water. Then lay it down on the waxed board and hold in place while it dries out with the gummed paper strips that have also been wetted. As the paper dries, it will shrink and the end result will be that the paper is stretched taught and held down on the waxed mosaic board which can then be reused indefinitely.

GLUING DOWN TESSERAE FOR AN INDIRECT MOSAIC. 

Any water-soluble glue or gum can be used.
I recommended wallpaper paste as it is cheap and you can mix it to the quantity and viscosity that you prefer. Use the glue sparingly as it only needs to act as a temporary fixing. Too much glue will make the brown paper buckle, but if you have stretched it properly then the buckling will not be too great.
In any case, it will shrink back again, but make sure that your tesserae have not been laid too close together otherwise they will get 'scrunched up' when the glue dries and

HINTS ABOUT DESIGN AND CHOOSING COLOURS

• Keep your design simple and uncluttered. Make sure that you have a strong tonal contrast between the subject and its background so that the subject stands our visually, even from a distance. Be kind to your mistakes. If you get it wrong, you will get it right next time.Remember that tonal contrast between the subject and the background is of vital importance. If the two are totally similar, then from a distance the subject will disappear.
• It is a good idea to limit the colour palette, at least until you are an experienced mosaicist. One or two carefully chosen colours are usually more effective than a whole spectrum.
• Don't be frightened of having plain areas of mosaic. For example, look at the Frog splashback. The plain area is necessary to stress the fact that the frog is swimming. On your initial design, plain areas look boring, but when mosaiced they become a necessary part of the overall piece, emphasizing that this is a mosaic that we are looking at. If the entire picture surface is busy, this effect is lessened somewhat. If in doubt, simplify. Consider the silhouette of your subject, say, a gecko. If it works as a silhouette, then it will certainly work when it is 'filled in'. If the silhouette is messy and incongruous, the finished piece may not look good either. This is why creatures such as fish, geckoes or butterflies, which have clear outlines, are so popular with mosaic artists.
• Think in terms of whether your colours need to be 'warm' or 'cool'. Basically, a warm colour is one that contains red, while a cool colour is one that contains blue. Thus purple, which is a mixture of red and blue, can be warm or cool depending on whether there is a predominance of red or blue. I find that this can help enormously when I am having trouble choosing a colour, say for a background. If I want the overall effect to be warm I can choose, say, a caramel or a soft pink. If cool, then a pastel blue or green may be more appropriate.

the paper re-streches.