Tesserae

Glass mosaic tesserae are small squares of coloured glass, usually smooth on the front and slightly ridged on the back, which aids adhesion. They are often used in swimming pools and bathroom floors and walls. They can be used whole for borders and are easily cut and shaped with tile nippers for more intricate designs. Widely available in a large range of colours and styles, prices range according to colour, quality and supplier. It is usual to buy them in sheets.

Ceramic tiles range from colourful to plain, bright, hand-painted designs, many different shapes and sizes. They are ideal for covering large areas quickly. Ceramic tiles can be both glazed and unglazed. Unglazed tiles are well suited to designs that have a natural, earthy colour, but they can also be used to provide contrast within a highly colourful, 'glossy' mosaic. Look out for discontinued lines. Tiles that are a little too bright or old-fashioned once cut into tesserae and used in small areas take on a whole new life.

Unusual and colourful old china cups and plates add interest and detail, and provide a contrast with plainer tiles. Raised patterns, or even the handles from tea cups or coffee mugs, give it a three-dimensional effect. Second-hand shops or garage sales are great places to start. And ask friends and family to save their broken plates or cups.

Pebbles and stones can look very effective in a mosaic, Collect them from the beach or river bank and try to select ones that are similar in size. Marble, slate and granite are also suitable stones for mosaic work.

Coloured glass, mirror, glass beads and pieces of terracotta pots. Glass tiles In Australia many tile shops display an extensive range of colours of glass tiles (in particular, the Italian brands) but, unfortunately, you will not be able to purchase many of the more unusual or striking colours unless you are prepared to buy an entire palette load from the overseas supplier.

Hint Take care when you buy your tiles that they are all of the same thickness. For many projects this is not a problem, but if a uniform, flat finish is required (e. g. a table top), it can be difficult to achieve.

Bases

There are many suitable surfaces but make sure you choose a base according to where you are planning to use it. A high grade plywood or medium density fibreboard (MDF) are suitable as they are strong and warp-resistant. If the wood is likely to come into contact with water, seal it to prevent moisture entering the wood, causing the adhesive to fail and the wood to warp. Some mosaicists prefer to seal all wood before use.

Where the mosaic is likely to come into contact with constant damp or wet, such as in the bathroom or behind the kitchen sink, a waterproof base, such as fibre cement sheet, is needed. Ask your supplier to cut it to size.

If working on a previously painted surface, sand the surface lightly before use. This provides a 'tooth' for the adhesive. Porous surfaces, such as terracotta, should be sealed before use.

Adhesives

A quality adhesive is essential to any mosaic work. There are many types to choose from and new products arc launched frequently, but there is no strict rule as to what you should use. If in doubt, talk with your hardware or tile supplier to ensure you make a suitable choice.

Adhesives are broken into two main groups: latex-based multipurpose and cement-based adhesives.

Multi-purpose tile adhesive is a two-part adhesive designed to withstand movement and provides great strength. It bonds exceptionally well, is easy to work, and is suitable for many mosaic applications. When cured, the adhesive is completely unaffected by water. It is purchased in two parts: a liquid and a rubbery powder. Mix the two parts together just before use, following the manufacturer's instructions. This adhesive is usually sold in bulk quantities, mainly for commercial rise, but there are some water-resistant adhesives that are sold in pre-mixed tubs, which is ideal for small jobs.

Cement-based tile adhesive is waterproof, long-lasting and bonds very well with the porous surfaces of terracotta and cement (this is the adhesive used for swimming pools). As these surfaces are in frequent, if not constant, contact with water, a high grade cement-based adhesive, such as this, should be used.

Wallpaper paste is used to temporarily bond tesserae to craft

Grout

Grout is the paste used to fill the gaps, or interstices, between tesserae. It strengthens the mosaic and gives the surface a less jagged finish. Grout is commonly sold as white or grey, but a reasonably extensive range of coloured grouts is available at most hardware stores.

Take your time when choosing a grout colour as this is essential to complement the finished design. As a general guide:

If you want a bold, well-defined mosaic, choose a grout colour dissimilar to any of the tesserae. This will bring out strong contrasts within the design.

For a softer, unified design, aim for a grout in a similar tonal range to the mosaic clcments.

When you're not sure what colour grout to use, grey is always a safe, neutral option.

Plain cement can also be used as a grouting medium.

Source: Mosaics (Murdoch Books) (out of print)