Mosaic Bases - Materials and Preparation

To ensure a good bond between the mosaic tesserae and the base, the surface must be clean and free from flaking paint, dirt and dust.

Remember that the base of the mosaic is like a spine and has to be able to support the entire weight of the tesserae, adhesive and grout - You can't put heavy thick pebbles on a 9mm plywood base!

Mosaic base considerations

The following guide contains information about the different types of mosaic bases that you can use and the special considerations required when using each type:

• Preparing the Mosaic Base Surface

When applying a mosaic to any glazed surface, be sure to rub it over with steel wool or sandpaper to create an adhesive surface. In order for the tesserae to stick to the base at maximum strength, it is often necessary to scratch the base top to create a stronger bonding surface.

Sandpaper is better for the more grainer surfaces such as terracotta, wood, ply-wood and MDF. Sanding and priming a wooden base will help prevent your mosaic base from cracking or getting wood rot which in turn will add to the longevity of the mosaic art piece.

Sandpaper can be used to smoothen the edges of wooden bases so that once the mosaic has been completed you won't get splinters.

Use steal wool or scouring pads and scratch the top of glass or mirror, metal and very smooth surfaces, by rubbing the wool in circles.

• Using wood as a mosaic base

You can use very thin wood boards for mosaic plaques or pot holders. However, if the wooden board is around 9mm thick (about 1/3rd of an inch) then I wouldn't suggest making the mosaic larger than 30 to 40 cm squared (11 to 15 inches).

If you are making a larger mosaic then you will need a thicker wooden board, starting at around 12mm (1/2 inch) and up. This will give support and strength to the mosaic as the tesserae required to cover and area of that size will be heavy and would possibly break a smaller board over time.

• Using glass, bottles or mirrors as a mosaic base

When using glass sheets, glass bottles or mirrors as a mosaic base you must make sure you use special glass glue as ordinary tile adhesive may not be strong enough and may also have an undesirable color.

When you are placing glass tiles on a glass mosaic base it is vital that you use clear, see-through glue in order to achieve the maximum potential of the light reflection.

This is especially important when creating a mosaic lamp shade or sconce as if you use heavy glue then you risk blocking light. It is also a good idea to hold your colored glass against a light bulb or the light shade before you start your mosaic to see whether the color will give you the desired ambience.

Some of the darker glass shades can severely reduce the amount of light supplied by the newly mosaiced shade, so it is often better to stick to the lighter colors like yellow, pink, orange, red and pale purple.

• Using metal as a mosaic base

When using metal as a mosaic base, for example when building mosaic garden tables, frames or garden sculptures, make sure you toughen up the often glossy surface with steel wool and examine the base closely for rust.

If you find patches of rust, treat them before you create your mosaic! Many times rust can have only a small effect on a mosaic however you don't want to spend hours creating a masterpiece only to find in a year's time that the base is no longer structurally sound!

• Choosing a base for an outdoor mosaic

Always keep in mind where you are planning on putting your mosaic once you have completed.

If you are putting it in the garden you need to use a sealant on the base, tiles and grout in order to waterproof the mosaic.

Outside mosaics need exterior based plywood (marine ply). Marble and Ceramic mosaics need a thick heavy base, hence terracotta and garden planters are an excellent medium.

Always consider that most surfaces, whether intended for either inside or outside use, need to be strong, dry and able to take the weight of the mosaic.

• Choosing a base for an indoor mosaic

The options for choosing the base material of an indoor mosaic are a little broader than when creating an outdoor mosaic.

Wood is obviously the most ideal base because of its strength and texture and there are many types of available. It is not necessary to use expensive or colored wood as the surface will be covered with tesserae.

You can use any kind of plywood or MDF (medium dense fibreboard) which is a fantastic medium because it will not warp or swell with atmospheric changes.

Your vote is highly appreciated.