Glazed Tiles vs Unglazed Porcelain Tiles

<p>Ceramic tile industry seems to have almost as many ‘types’ of tile as it has ‘styles’ of tile. As we all know, in half a dozen different colours, with glazed mosaics from Japan on the floor.</p><p><br></p><p>We have vitrified porcelain, both full-bodied and double-loaded, and a plethora of <a href="https://www.overlandceramics.com/glazed-tile" rel="noopener noreferrer" target="_blank"><strong>glazed porcelain tiles</strong></a>, 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.&nbsp;</p><p><br></p><p>Definitions</p><p>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. <a href="https://www.overlandceramics.com/product" rel="noopener noreferrer" target="_blank"><strong>Ceramic tiles</strong></a> can be produced using either the MONOCOTTURA or BICOTTURA method. The monocottura 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.</p><p>&nbsp;</p><p><br></p><p>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.</p><p><br></p><p>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 <a href="https://www.overlandceramics.com/procelain-tile" rel="noopener noreferrer" target="_blank"><strong>porcelain tiles</strong></a> 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.&nbsp;</p><p><br></p><p>Vitrification: Is a process. It is the transformation of melted clay into a ‘glass-like’ substance with a porosity of &lt;0.5%. The greater the vitrification the harder the tile and the less porous it is, meaning the less likely it is to absorb liquids and be stained, and the harder the surface the less likely it is to scratch or chip. Of course, the less likely moisture is to penetrate the surface of a tile the more likely it is to sit on the surface, which can, depending on the texture of the surface, increase the potential for slipping.&nbsp;</p><p><br></p><p>There are four types of vitrified tile: full body, double loaded, glazed &amp; soluble salt. For several reasons this last type is not something that will be considered in this article.</p><p><br></p><p>Unglazed Porcelain:</p><p><br></p><p>Full-bodied porcelain is a type of vitrified tile where the colour runs right through the body with a single colour from the surface to the base of the tile. Not only is the colour consistent throughout, but the technical properties, such as water absorption, frost &amp; acid resistance are also consistent.</p><p><br></p><p>Polished Unglazed Porcelain: Polished porcelain is shiny but it does not have a gloss glaze on it. It is an <a href="https://www.overlandceramics.com/unglazed-tile" rel="noopener noreferrer" target="_blank"><strong>unglazed tile</strong></a> that has been mechanically polished in the same way that marble or granite tiles are polished to make them shiny, and just as polished marble or granite tiles need to be sealed to prevent them from being stained, so does polished porcelain.&nbsp;</p><p><br></p><p>When porcelain is polished its technical characteristics are altered, especially its absorption level. Because of its finely textured surface, standard, or ‘matte’ porcelain does not absorb dirt and stains, but can exhibit soiling which is confined to the surface of the tile and can be easily washed off. Mechanical polishing by the factory creates a smoother surface, which is much less likely to grab and hold dirt from shoes, etc, but damages the micro beads of porcelain dust and opens up the micro pores of the tile rendering the surface more porous and susceptible to staining, necessitating the use of a penetrating sealer. Polishing, which grinds the surface of the porcelain smooth - to a shiny, mirror finish, also results in the tile becoming slippery when wet. (Shopping malls tend to prefer <strong>polished porcelain tiles </strong>for their public thoroughfares because they are easier &amp; cheaper to clean, despite the fact that they are more slippery, i.e. dangerous, when wet.) Once a penetrating sealer has been applied to the surface of the polished, or lappato, unglazed porcelain tiles it then becomes necessary to clean them using a specially formulated pH neutral cleaner. Standard floor cleaners have a high pH level, which breaks down the sealer, shortening its life and reducing its efficacy.</p><p><br></p><p>Glazed Porcelain: Most people assume the word glazed means ‘shiny’ or ‘glossy’. However, in the tile industry the word is used to refer to the coloured or patterned coating that is applied to the surface of a tile. Glaze is a substance rather than a description of a textural finish, e.g. one can have marble that has a ‘glossy’ surface or&nbsp;unglazed porcelain that is ‘glossy’, but neither products are ‘glazed’. Think of glaze like paint - just as you can have a matte paint for your walls, and a gloss paint for your doors and skirting. Glaze is paint for your tiles.&nbsp;</p>