| It all begins with the raw materials. In order to be frost
proof exactly the right clay has to be used. This can also be achieved, by
mixing several clays from different deposits together. This mixture is a closely
guarded secret. Clay was usually formed by glacial movements in the last Ice
Age. Big rocks and other non desired materials are sorted out directly
in the pit. The raw clay gets then transported to the processing plant by
conveyer, truck or train. |
clay mining by excavator
clay mining by bucket wheel excavator |
| In the factory, work on the raw clay starts by unloading
into storage pits. |
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| Some factories soak the raw clay in large soaking pits. This
also allows the factories to stockpile large quantities of material. |
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| In the drying process the hard work for the clay begins.
Feeders and grinders work it over. To achieve small particles and a homogeneous
texture pan grinders smash the clay into a fine powder. |
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| A further step is to pass the wet clay through a fine screen
press. |
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| The final processing step is the rolling mill in which the
clay is rolled between large rolls, just like backing dough. |
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| Out of a super large extruder a constant string of clay is
pressed onto a conveyor belt. It is then cut to size. |
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| The next step is to form the raw clot into the shape
desired. This is done by pressing the clay clots into a two-piece form under
high pressure. Basically two rotating drums press the constant stream of
clay clots into form. |
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| The formed raw tiles get stacked and left to dry into a
special chamber. |
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| After drying, it is time for the color application. Special,
secret mixtures of colors are used to be applied by spraying it onto the
exposed surface. Engobes produce a matt to semi-shiny finish after burning.
Random spray patterns allow for the tile to look aged. Glazes produce high-glossy colors with a glass like surface. |
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| After the sprayed on color has been dried, the tiles get placed into
a firing tray. These trays get stacked onto a dolly, ready for the burning process. |
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| Modern factories use hydro-casing tunnel kilns. In there, the
tiles get gradually warmed up until the desired burning temperature is
reached. After burning, it is important to slowly lower the temperature.
All this is computer controlled, but it is still necessary to have a human
at the controls, which has long time experience with the process. Since
clay is a natural product, small variations in it make it absolutely
necessary to "fine tune" the burning process to constantly achieve
a product that is always of the same high quality and consistence. Burning
temperatures sometimes exceed 1100°C (2012°F). |
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| The burned clay tiles undergo a rigorous quality testing
that incorporates several steps and tests. One of the tests is an acoustic
test. A small wooden hammer bangs the tile. The denser (better quality)
the tile is, the clearer the sound is (just like a bell would sound). This
way any imperfections can be sorted out. |
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| If the tiles have passed the quality control, they get
stacked automatically onto pallets. Many steps in the modern
production of clay roofing tiles is automated. This is for several reasons:
one is that the work is often dusty and hot. Also production runs in a 24
hour/350 days a year process. The kilns can not be shut down in the night
or on holidays since firing it up takes several hours. In order to have a continuous
production, automation is in place. The packaged tiles get into a
temporary holding yard until they get picked up for shipment. |
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| Specialty tiles, that can not be produced using machines,
have to be made by hand. This applies for verge tiles (rakes), vent tiles,
etc. but also for decorative roof ornaments. |
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| Modern production facilities take up huge spaces. In the
past years the emphasis has been the reduction in the use of energy and
the integration of environmentally friendly production processes. All of
our manufacturers implement "re-use and recycle" into their
production. One of the biggest and most modern production today is the
Creaton production in Grossengottern. |
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| The tiles get delivered to the job site on flat bed trucks. |
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| The end result of the production is a durable, long lasting
roofing product with countless benefits that is made out of four of the
Elements: Earth, Water, Air and Fire. |
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