• Journal of the Korean Ceramic Society
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• v.41 no.11
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• pp.834-841
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• 2004

The purpose of this study is to investigate the properties of traditional Korean ash glazes by using locally available sources; 10 kinds of grain stems,2 kinds of husks (pod, chaff), and 4 kinds of vegetables (spinach, radish leaf and stem, pumpkin leaf and stem, pepper stem), and to develop their practical uses as ash glazes. The test results of these ash glazes indicate that these ashes can be classified into four categories. The first group, which includes perilla stem ash, sesame stem ash, black bean stem ash and red-bean stem ash, shows strong milky white due to relatively lower content of $SiO_2$, and relatively higher content of CaO and P$_2$O$\_$5/ content (10% higher than others), and their glazes were found to be suitable for opaque glaze as they show relatively stable bright greenish color. The second group includes pepper stem ash, spinach ash, pod ash, radish leaf and stem ash, and bean stem ash, and this group was found to contain even quantity of every component. And their glaze show somewhat greenish color because of especially high content of MgO and more than 2% of Fe$_2$ $O_3$. They were found to be suitable for basic glaze of IRABO glaze. The third group, which includes com stalk ash, white bean ash, pumpkin leaf and stem ash, has more $SiO_2$ and Al$_2$ $O_3$ than other ashes, and it also contains 3～5% of Fe$_2$ $O_3$. As a result of those components, this third group shows the greatest change of color and chroma, and was found to be suitable glazes as basic glaze of Temmoku and black glazes. The fourth group (reed ash, rice straw ash, indian millet stalk ash and chaff ash) has as much as 45～82% of $SiO_2$ and relatively lower content of Fe$_2$ $O_3$ and P$_2$ $O_3$. This group shows blue or greenish white color, and was found to be suitable as the basic glaze of white glaze.

• Analytical Science and Technology
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• v.26 no.3
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• pp.211-221
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• 2013

This research aims to examine compositional and microstructural properties of grayish-blue-powdered celadon in Wonju Beopcheon-temple site. X-ray fluorescence sequential spectroscopy (XRF) with micro-point analysis, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were applied to determine the chemical composition, microstructure and crystallinity of samples, respectively. As a result, the average compositions of bodies were low silica ($RO_2$) and high flux (RO+$R_2O$). Owing to the high content of calcium oxide the glaze is considered lime type between limealkali type. The body of celdon sheard was found quarts, mullite, microcline, albite. Especially, the body's chemical compositions were compared to the results of previous studies by using a Seger formula. The compositional properties of Grayish-blue-powdered celadon in Wonju Beopcheon-temple site showed diffrently from the the other grayish-blue-powdered celadon.

• Korean Journal of Materials Research
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• v.23 no.4
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• pp.233-239
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• 2013

We collected Seokganju minerals (regions in Gyeryong Mountain, Sangsin-ri, Banpo-myeon, Gongju Chungcheongnam-province), which were used as natural color pigments for grayish-blue during the 15th~16th centuries of the Joseon era, and investigated their crystallographic features to develop a black pigment having a spinel structure. By a Raman analysis, the color of Seokganju under transparent glaze as a pigment for painting was black because hematite ($Fe_2O_3$) in Seokganju was converted to magnetite ($Fe_3O_4$) However, Seokganju into the transparent glaze as a pigment was brown because of hematite ($Fe_2O_3$) and small amounts of maghemite (${\gamma}-Fe_2O_3$) in Seokganju minerals. Only Seokganju mineral is used, it is not suitable for black pigment into the transparent glaze. This study tried to develop a spinel crystal black pigment stabilized by Seokganju with CoO, $Cr_2O_3$, NiO, and $MnO_2$ at $1280^{\circ}C$. A Raman spectroscopy analysis was performed to verify the presence of Mn The results showed that it existed as spinel, and two crystal phases $CoFe_2O_4$ and $MnFe_2O_4$ were mixed. $CoFe_2O_4$ spinel has a dark grayish black color and $MnFe_2O_4$ spinel has a greenish black color, and these two appeared as black. The color of a specimen calcined by adding 6 wt% of pigment mixed with 5 wt% of $MnO_2$ added to lime glaze was analyzed with a UV spectrophotometer. When applying the color pigment, it appeared black stabilized with $L^*$24.23, $a^*$ 0.12, $b^*$ -2.29 at $1260^{\circ}C$ oxidative calcination, With $1240^{\circ}C$ reduction firing, it is appeared black stabilized with low brightness of $L^*$ 23.13, $a^*$ -1.12, $b^*$ 0.54.

• Journal of Conservation Science
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• v.36 no.4
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• pp.275-283
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• 2020

Iron oxides are the essential coloring oxides in traditional ceramic glazes. However, when Fe is involved in the coloration in the form of ions or colloids in glazes with low Fe content, it is difficult to identify the iron oxide phases. Generally, in many these glazes, Ca-rich minerals are observed by X-ray diffraction (XRD) or microscopic images, owing to their devitrification by the high Ca content. This study attempts to elucidate the correlation between the crystalline structure and coloration in the glazes while mainly focusing on neoformed Ca-rich minerals and Fe content. An experimental firing was carried out to produce tree ash glazes, with pine tree ash and Buyeo feldspar. In the case of oxidation glazes, the scanning electron microscopy (SEM) images and XRD patterns did not exhibit any Ca-rich crystals, and all the visible light reflectance spectra lines exhibited a similar shape. In contrast, the reduction glazes divided into blue glazes and other colored glazes according to the shapes of their reflectance spectra. It was confirmed that the influence of Ca-rich minerals on the glaze color was more pronounced than the blue color of the reduction glazes when the Ca and feldspar contents were sufficiently high and low, respectively, to form wollastonite. As the Ca content increased and the elemental composition of the reduction glazes changed, the neoformation of the Ca-rich minerals, such as wollastonite, anorthite, diopside, and akermanite was sequentially observed.

• Journal of Conservation Science
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• v.32 no.2
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• pp.123-139
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• 2016

The excavated potteries of Goryeo Period from the Sandongri archaeological site in Seosan were studied on physicochemical analyses. Surface color of the samples are mainly grayish blue, and showed the natural glaze by melting the body soils during the burning. Partly, swelling surface are observed bloated marks because of blow out gas by burning. The potteries are some possibility of making the similar source clay on the basis of magnetic susceptibilities (about $1{\times}10^{-3}SI\;unit$) and general occurrences. Values of specific gravity, apparent porosity and absorption ratio are divided two groups as highly different cases of bloating surface samples. The source clay of the potteries used mainly microcrystalline clay, the mineral compositions are quartz and some colored minerals. Based on the analysis, the burning temperature of the potteries are assumed that they were around $1,100^{\circ}C$ because detection of quartz and mullite within hard and compact matrices. As geochemical variations of the samples, evolution trends of rare earth, compatible and incompatible elements showed very similar patterns excepting the some major elements, that means the potteries are interpreted to making by elutriation processes using the same raw clays from very similar basement rocks of genetically.