It is one of the oldest materials used in pottery. To overcome its porosity, the fired object is covered with finely ground glass powder suspended in water glaze and is then fired a second time.
Faience, Delft and majolica are examples of earthenware. Because stoneware is non-porous, glaze is applied only for decoration. It is a sturdy, chip-resistant and durable material suitable for use in the kitchen for cooking, baking, storing liquids and as serving dishes.
Porcelain is a very hard, translucent white ceramic. The earliest forms of porcelain originated in China around BC, and by AD, Chinese porcelain was a prized commodity with Arabian traders.
To make porcelain, small amounts of glass, granite and feldspar minerals are ground up with fine white kaolin clay. Water is then added to the resulting fine white powder so that it can be kneaded and worked into shape. Decorative glazes are then applied followed by further firing. Bone china — which is easier to make, harder to chip and stronger than porcelain — is made by adding ash from cattle bones to clay, feldspar minerals and fine silica sand.
Advanced ceramics are not generally clay-based. Instead, they are either based on oxides or non-oxides or combinations of the two:. Depending on their method of formation, ceramics can be dense or lightweight. Typically, they will demonstrate excellent strength and hardness properties; however, they are often brittle in nature. Ceramics can also be formed to serve as electrically conductive materials, objects allowing electricity to pass through their mass, or insulators, materials preventing the flow of electricity.
Some ceramics, like superconductors, also display magnetic properties. Ceramics are generally made by taking mixtures of clay, earthen elements, powders, and water and shaping them into desired forms.
Once the ceramic has been shaped, it is fired in a high temperature oven known as a kiln. Ceramic clays and semi-acid clays are used in brick masonry construction, terracotta tiles, or cement. Al 2 O 3 can be used for the extraction of alumina in the synthesis process; and strong base and basic clays refractory clays are used in the manufacture of refractory chamotte for the manufacture of fine ceramics.
Clays always contain a greater or lesser amount of impurities, which reduce refractoriness [ 69 ]. For aesthetic and for a consistent colored ceramic, pigments are used with metallic oxides and different salts.
Pigments vary from green to blue-green to blue. They can be used as dyes in clay bodies and glazes, directly or mixed with water. The coating is constituted of lead-alkali glass with the addition of copper or iron ions as coloring agents. The presence of the oxides is vital. For example, chrome oxide gives green color, but it may fume or volatilize.
If tin is present in a white or pastel glaze, the chrome reacts with the tin to create a pink coloration. If zinc oxide is present in the glaze, a dirty-brown color will be obtained. For green color, cobalt-zinc-alumina-chromite blue-green pigment system could be used, where varying the amounts of cobalt and chrome oxides produces a green ceramic color.
Many pigments have mineral origin with different colors; for example, ocher: red and yellow; cinnabar: bright red; azurite: blue; malachite: green; lime: white; carbonized bone: black. As organic pigments red madder and murex shell purple are used, and as binding media, egg, casein, and wax.
The chemical compositions of the ancient ceramics and pigments used are shown in Table 4. Montmorillonite could be derived from hydrolysis process occurring during the burial period of the findings [ 71 ].
Calcite, as clearly shown by the FT-IR spectrum in which the large band centered at about cm —1 and the contribution at about cm -1 , typical of this mineral, is present. The absorptions from the main quartz phase Si—O could also be easily identified in the FTIR spectrum of ceramics and pigments used for glaze Figure 8 ; , , , , , cm —1 [ 72 ].
The several intense bands in the range — cm —1 , , cm —1 are characteristic of the metal—oxygen vibrations in the ceramic samples [ 73 ]. However, additionally the characteristic carbonate calcite phase vibrations at , , , cm —1 [ 74 ] and M—O vibrations at , , ,, cm —1 could also be determined. Broadbands between — cm —1 can be assigned to the adsorbed water or water of crystallization and O—H vibrations of glazed pottery.
This could be associated with specific surface properties of pottery, which stimulate adsorption of moisture from atmosphere at ambient conditions.
The Raman spectra collected have to be compared with those obtained previously from reference materials. Published libraries of spectra are now widely available in the literature on historical pigments [ 75 , 76 ], enamel and glazing pigments [ 77 ], modern synthetic pigments [ 78 ], modern inks [ 79 ], gums, waxes, varnishes, resins and other binders of historical and archaeological importance [ 80 , 89 ], minerals [ 70 , 90 , 91 ], and plant fibers [ 92 ].
As already mentioned, Raman scattering is a very weak phenomenon that requires an intense monochromatic light source to generate a readily detectable effect.
Also, the use of lasers has allowed a wider choice of excitation lines, with wavelengths ranging from The cm —1 band is also assigned to hematite. When the sample has been produced in an oxidizing atmosphere, the most important indicator is the hematite [ 90 , 93 ].
If magnetite is present, this is an indicator of its incomplete phase transformation into hematite [ 91 ]. The Raman spectrum of the tile ceramic is shown in Figure 9. The representative Raman band for beta-quartz is located at cm —1 , while the medium intense cm —1 band is assigned to albite Na-feldspar. Specific bands appear here: , , cm —1 , all being attributed to quartz.
The band from cm —1 together with the shoulder around cm -1 indicates the presence of hematite. All these are more pronounced for not-glazed face red colored spectrum.
Also, in the Raman spectrum of the ceramic supports, the medium intense— cm —1 —band reveals the presence of hematite, as shown in Figure FT-IR spectra of the pigments. Many ceramic pieces known as ceramic heritage have been discovered, characterized by specific techniques of characterization either for raw materials or ceramic objects based on clays, discovered in different archaeological sites, leading to some results about the production technology, provenance, authentication, and historical appartenance.
The chemical composition of ancient ceramics and pigments decorating them, excavated from different Romanian archaeological sites, suggested a chemical composition of ceramic based on clay minerals kaolinite, illite, and smectite , while the pigments belonging to them contain hematite or ocher a red pigment , manganese oxides brown pigments , and magnetite or carbon of vegetable origin black-pigmented layers. This paper received the financial support of the projects: PN Licensee IntechOpen.
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Edited by Gustavo Morari Do Nascimento. We are IntechOpen, the world's leading publisher of Open Access books. Built by scientists, for scientists. Our readership spans scientists, professors, researchers, librarians, and students, as well as business professionals. Downloaded: Abstract The artifacts belonging to the ceramic heritage are mostly based on all clay types used by humans over the ages, because the sources of clays were easily available and people were interested to produce ceramics and pottery.
Keywords Cultural heritage clays pottery ceramics Transylvania tiles. Introduction In ancient times, sources of clays were widely available, between them soils or surface sediments have been the proper sources for ceramics without further treatment, due to their natural mixture of plastic and nonplastic components [ 1 ]. Traditional ceramics The traditional ceramics involve those materials that are derived from common, naturally occurring raw materials such as clay minerals and quartz sand.
Romanian history of ceramics Ceramics, until the twentieth century, was essentially used for utilitarian purposes for ritual acts.
Analytical techniques for investigation Modern chemical methods and measuring techniques can be used for archaeometric purposes. Table 1. The ceramic samples analyzed. Element Ceramic Enamel Si Table 2. Table 3. Historical aspects It seems like ancient tiles appeared in Germany around Ceramics support Ceramic is a type of kaolin as hydrated aluminum silicate double, feldspar formed by the decomposition of igneous rocks and by the action of carbonic acid and water, under pressure, and subjected to high temperatures.
Pigments for glazed tile For aesthetic and for a consistent colored ceramic, pigments are used with metallic oxides and different salts. Table 4. Chemical composition of the Transylvania tile. More Print chapter. How to cite and reference Link to this chapter Copy to clipboard. Available from:. Over 21, IntechOpen readers like this topic Help us write another book on this subject and reach those readers Suggest a book topic Books open for submissions.
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