Ceramic tiles are tiles that are made of clay that’s been baked at extremely high temperatures. To create the tiles, the clay is first moulded and cut into the desired size and shape, then it’s baked or fired in a type of oven called a ‘kiln’ - usually at around 1000º Celsius - until it becomes hard. There are a few small variations on this method, depending on the kinds of properties and finishes that are needed.
Ceramics have been used for thousands of years, not only for tiling but also for pottery and sculpture.
What are glazes – and what do they do?
Most ceramic tiles are coated with what’s called a ‘glaze’. A ceramic glaze is a coating that’s applied and baked onto the surface of the tile.
Glazes are used on tiles for a few reasons:
- To improve waterproofing – With a few exceptions (and depending on how they’re made), unglazed ceramic tiles tend to be pretty porous, meaning that they easily absorb moisture. Glazes help to waterproof the surfaces of the tiles, making them more suitable for areas where they’re likely to get wet.
- To strengthen the tiles - Glazes also bond to the surface of the tile to form a strong outer shell, which helps to make tiles stronger and more durable.
- To decorate the tiles – Glazes are what give ceramic tiles their colours, patterns and finishes (i.e. how much of a gloss or matte surface the tile has). Glazes can be applied in stages to create layers of colours and patterns on tiles.
Glazes are applied to tiles in a variety of different ways, including:
- as a liquid applied to the surface of the tiles
- as a dry mixture coated over the top of the tile before firing, or
- by adding salt or soda into the kiln during the high temperature part of firing (i.e. as with salt or soda glazes).
Colour and tonal differences in ceramic tiles
Making tiles is a fairly careful process these days, but it's always the case that there are subtle colour and tonal variations between different firings - arguably part of the charm of ceramic tiles. For this reason it's always important to try and buy tiles that are all from the same batch, wherever possible.
For the same reason, it's also important to make sure you buy more tiles than you need, so that should anything go wrong you'll have some replacements that match the ones you've already got installed. As a rule of thumb, you should aim to buy 10% more than you'd need to cover whichever wall or floor surface you're planning to tile - this also accounts for cutting.
Tiles are normally laid by mixing tiles from different boxes to help ensure that these subtle variations are carefully blended.
Monocottura and bicottura
There's a decent chance you'll run across either one or both of these words at some point when you're looking at tiles. Put simply:
- Monocottura means 'single fired', and refers to the fact that these tiles are moulded, cut, glazed and then fired in a kiln only once. Monocottura tiles tend to be stronger and more durable, and therefore much more appropriate for floor tiles than bicottura.
- Bicottura means 'double fired'. Bicottura tiles are first fired without a glaze. The biscuit of the tile is then glazed and fired again. The Bicottura method is generally believe to make better decorative tiles. Because bicottura tiles aren't as durable, they're normally more suited for use as wall tiles.
Ratings for ceramic tiles
Ceramic tiles are rated based on how much wear and tear they’re likely to be able to take. These ratings range from 1 through to 5:
- Class 1: Low traffic areas like bathrooms and bedrooms
- Class 2: Medium traffic areas like living rooms
- Class 3: High traffic areas like corridors, kitchens, balconies and lobbies.
- Class 4: Very high traffic areas like busy porches, work rooms etc. (typically non-residential)
- Class 5: Extremely high traffic areas like commercial floors in shops.
Isn’t porcelain a type of ceramic?
Technically, yes – porcelain's a type of ceramic. But porcelain tiles are made differently and have different properties, so they’re usually referred to very specifically as ‘porcelain tiles’ rather than ceramic tiles.
Porcelain tiles are tough and waterproof by nature, and don’t usually need a glaze like ceramic tiles do unless it’s for decorative purposes.
Are ceramic tiles expensive?
Because they’re made of inexpensive materials and they can be manufactured without a whole lot of fuss, generally speaking ceramic tiles are the most affordable type of tile. Having said that, it's entirely possible to pay much more for nicer, elaborately finished ceramic tiles if that's what you're after.
As with all tiles, the expensive part’s normally the installation process which, while not usually that complicated, can be a bit slow and labour intensive (particularly with smaller tiles). If you're looking to keep costs to a minimum and you have the time and energy to spare, you may want to offer yourself up as extra labour to help install them.
What should I look for?
Ceramic tiles can be used all over your house (i.e. as floor tiles, for splashbacks etc.) - the important bit is to make sure you're buying ceramic tiles that are suitable for the particular purpose you have in mind. That comes down to how durable and watertight the tiles are, and in most cases that's as easy as just asking whoever's selling them to confirm they're the right type and rating.