Topic: The Difference Between Glazed And Unglazed Porcelain Tiles
The Difference Between Glazed And Unglazed Porcelain Tiles
Today’s ceramic tile industry seems to have almost as many ‘types’ of tile as it has ‘styles’ of tile. We have certainly come a long way since the 1970s when most bathroom wall tiles were a 6” square Johnsons “chicken” tile, as it came to be known, in half a dozen different colours, with glazed mosaics from Japan on the floor.Get more news about Glazed Polished Porcelain Tile,you can vist our website!
Nowadays, as well as the bicottura and monocottura types that dominated the residential market until the late 1990s, we have vitrified porcelain, both full-bodied and double-loaded, and a plethora of glazed porcelain tiles, available with a matte glaze, a gloss glaze, a ‘lappato’ a.k.a. semi-polished finish, plus a variety of textured, slip-resistant tiles. Likewise, unglazed, fully vitrified porcelain tiles come in a variety of finishes. It is not always easy to tell what sort of tile it is just by looking at it, but knowing the difference is important in order to choose the right tile for the situation, and to avoid mishaps and accidents.
To assist you in sorting your way through this maze of confusing terminology we have put together a helpful list of the most common types of tile and their performance characteristics, where to use them, and how to maintain them. We also correct some misconceptions and misleading information regarding glazed and unglazed tiles.
Ceramic tile: Is formed of clay, plus sand, felspar, quartz and water, which is then dried to a dust, pressed at great pressure and fired at temperatures ranging from 1000 to 1300 degrees Celsius, depending on the type of tile. Ceramic tiles can be produced using either the MONOCOTTURA or BICOTTURA method. The monocottura (from the Italian meaning “single fired”) method is generally used to produce floor tiles, though they can be used on the wall if desired. With monocottura tiles the body and the glaze are rapidly fired at high temperature at the same time. Until the late 1990s the vast majority of all residential floor tiles were made using this method.
Wall tiles, which have a wider range of colours and decorative surfaces, are produced using the bicottura method. Although the translation implies these tiles are fired twice, they may in fact be fired several times, depending on the number of layers of glaze applied. The firing temperature of bicottura tiles is lower than for monocottura tiles, as hardness is not the required result. Generally speaking, the higher the temperature the harder the tile.
Ceramic tiles have a water absorption rate of over 4%. The fact that they aren’t fully vitrified should not be seen as a fault or a limitation, as it is an unnecessary process in their manufacture.
Porcelain tile: Is actually part of the ceramic family, but distinct in its characteristics due to the types and mix of clays used, and the specific methods of production. Porcelain is a much stronger version of ceramic. Both types are made of clay and are fired in a kiln. The main differences are that porcelain tiles have a water absorption rate of less than 0.5%, a result which classifies them as fully vitrified, making them incredibly hard and rendering them suitable for heavy traffic floor use, including industrial situations. Porcelain tiles can be used in virtually any situation - from light traffic bathroom floors (and walls) to factory floors and swimming pools, both in (as mosaics) and around them.
This porosity rate is achieved due to three main factors: the incredible force used to press the clay - up to 100,000 lbs per square inch; the volcanic temperature at which it is fired - approx. 1250 degrees Celsius; and the mix of clays and minerals used. It is the difference in the clay mix - kaolin, felspar, quartziferous sand & metallic oxides, which is at the heart of all the other factors, for it is the clay which enables the extreme pressing and firing to occur. (Kaolin, a white china clay, is crucial in aiding the tile to maintain its shape during the firing process.) By injecting the pigmented dry dust clay into moulds and pressing at this incredible pressure the clay dust particles are compressed very close together, reducing the amount of air and moisture between the particles. This makes for a denser, less porous body. The nature of the porcelain clay is such that when it is fired at approx. 1250 degrees Celsius the dust particles melt and fuse together, resulting in vitrification.