• 보존과학연구
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• s.29
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• pp.199-220
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• 2008

Hobun(Oyster shell White) is a traditional material used as extender and white pigment from ancient times. The production method of it, however, has been discontinued. We have studied the traditional production method of Hobun by weathering oyster shell, which is one of the traditional ways for preparing Hobun. Reproduction study of manufacturing method of the discontinued traditional material is an important accomplishment of our research. Also this study provides solid background knowledge to stabilize the production and supply of Hobun for the cultural asset repairing materials. The result can be summarized as follows: The production process of Hobun by weathering method takes 5 steps - (1) weathering shells ${\rightarrow}$ (2) washing ${\rightarrow}$ (3) pulverization ${\rightarrow}$ (4) separating fine powder by submerging in water ${\rightarrow}$ (5) drying. The major aim in step (1) is to eliminate organic impurities. In the step (4), the fine particles smaller than $25{\mu}m$ are separated by extracting the supernatant from stirred suspension after heavy particles are submerged. Also, the soluble inorganic impurities can be eliminated through the powder submerge in 15 times water and stirring the suspension 6 hours and changing the water 3~4 times. The final products have high quality with 94.03, 0.52, 2.05 for L, a, b, less than $25{\mu}m$ particle size, fine resistance for discoloration by light and environmental pollution and good workability.

• Journal of Conservation Science
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• v.23
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• pp.103-118
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• 2008

Hobun(Oyster shell W.) is a traditional material used as extender and white pigment from ancient times. The production method of it, however, has been discontinued. We have studied the traditional production method of Hobun through calcination of oyster shell, which is one of the traditional ways for preparing Hobun. Our work has the important meaning in that we can reproduce the manufacturing method of the discontinued traditional material and also it provides a solid background knowledge to stabilize the production and supply of Hobun for the cultural asset repairing materials. The result can be summarized as followings: The production processes of Hobun by calcination method are divided into 4 steps - calcination ${\rightarrow}$ slaking(pulverization) ${\rightarrow}$ separating fine powder by submergence in water ${\rightarrow}$ drying. In calcination step, the temperature is required to exceed $700^{\circ}$ to get pure white color of Hobun, since organic materials in the shell cause the final powder to be less white below $600^{\circ}$. And the calcination methods produce significant amount of calcium hydroxide, which is incongruent for pigment materials without additional treatments. The experimental study also demonstrated that the additional treatment process introduced in traditional paintings can be a probable process since the calcium of potassium hydroxide is observed to be promoted by this treatment. It is also concluded that, the calcination method of Hobun is appropriate for a small amount and high quality production.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.899-909
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• 2023

In this study, the material scientific characteristics of Hobun pigments used as white inorganic pigment for traditional cultural heritage were identified according to the type of shell and calcination and evaluated the stability of the preservation environment. For the purpose of this, we collected 2 different types of Hobun pigments made by oyster and clam shell and its calcined products(at 1,150℃). Hobun pigments before calcined identified calcium carbonate such as calcite, aragonite but calcination derived changing main composition to portlandite and calcite. Results of FE-SEM showed characteristics microstructure for each shell but pigments after calcined observed porous structure. Porous granule highly caused oil adsorption according to increase specific surface area of pigments. In addition, the whiteness improved after calcined pigments compared to non-calcined pigments, and the color improvement rate of Hobun pigment (CS) which made of clam shell was higher. As a result of the accelerated weathering test, the Hobun pigment-colored specimen had a color difference value of less than 2 after the test, which was difficult to recognize with the naked eye. In particular, the color stability has improved as the color difference value of the Hobun pigment is smaller after calcined compared to before non-calcined pigment. However, it was confirmed that the stability of the painting layer was lower in the specimen after calcined pigment. For antifungal activity test, Aspergillus niger, Tyromyces palustris and Trametes versicolor were used as test fungi, and all pigments were found to have preventive and protective effects against fungi. Especially, the antifungal effect of the calcined pigment was excellent, which is due to the stronger basicity of the pigment.

• Journal of Conservation Science
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• v.32 no.3
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• pp.403-416
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• 2016

Mineral composition and content of 22 Korean Dancheong pigment products were obtained by Rietveld quantitative analysis. Jubosa, Hwang, Seokrok, Seokcheong and Hobun consist of pure cinnabar, orpiment, malachite, azurite and calcite (or aragonite), respectively. Whereas Seokganju, Hwangto, Noerok, Lapis lazuli, Baekto and Cockie hobun mainly consist of hematite, goethite, celadonite, lazurite, kaolin mineral and portlandite, respectively. And they all consist of soil minerals (quartz, feldspar, sericite and vermiculite) and filler minerals in the industry field (calcite, gypsum and anhydrite) at a different content. Quantitative XRD proved more useful method to determined exact mineral composition and content than chemical or microscopical data. If this method utilize for specification of natural pigment product, it is considered to be applicable in restoration technology and conservation science field.

• Economic and Environmental Geology
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• v.50 no.6
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• pp.497-508
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• 2017

This study was carried out to document and diagnose the conditions of the seated stone statue of Buddhist Master Seungga in Seunggasa temple immediately after its conservation treatment, which was found to be long covered in surface of white materials. The stone Halo was researched along with the Statue, and basic data was secured through precisely examination and nondestructive diagnosis. The result from the surface deterioration evaluation shows that both the Statue and Halo had a little bit of physical deterioration, although their level of chemical deterioration was proportionally higher due to discoloration. The physical property diagnosis using ultrasonic measurements on the Statue and Halo showed that the average ultrasonic velocity was found to be 3,570 m/s and 3,373 m/s, respectively, which corresponds to grade III, an indication of a favorable physical property. The surface covered materials were detected to be Ca, Ti, Pb, Fe, Al and Si, emanating from Hobun (Oster shell powder; $CaCO_3$) or lime ($CaO{\cdot}Ca(OH)_2$) and silicate minerals. Furthermore, Ti and Pb seems to be the component of the white coloring pigments, titanium white ($TiO_2$) and white lead ($2PbCO_2{\cdot}Pb(OH)_2$). Therefore, the seated stone statue of Buddhist Master Seungga is presumed to be painted with Hobun or lime and thereafter painted over with titanium white and white lead.

• Journal of Conservation Science
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• v.30 no.4
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• pp.447-456
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• 2014

This study is mainly about materials that are used in Sungnyemun gate's dancheong to find causes of dancheong's damage such as desquamation and peeling off. 12 kinds of pigments' components which are used in dancheoong are analyzed. Except for Hobun and Seokganju, the pigments are artificial. Samples are made with different conditions of adhesives and the rate of binder. To estimate promotion weathering test, adhesives are applied in a different order. Desquamation and peeling off presented especially when different adhesives are used on dancheong and also, generally the layer thickened.

• Journal of Conservation Science
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• v.32 no.2
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• pp.261-271
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• 2016

We have investigated relationship between particle characteristics of oyster shell powder pigments and their performance such as workability and durability. Three types of the powder which have different particle size and shape(spherical, elliptical, columnar and irregular) distributions were made for this study and we evaluated spreadability and uniformity for workability, and adhesion and surface hardness for durability of painted films by each powder paints. As a result, we found out that the workability and durability of the paints were influenced by the particle shape distribution more than the particle size distribution. The durability, especially, was enhanced as the ratio of columnar particles in the powders was increased. This result verifying the important factor affecting the durability can be base data for selecting oyster shell white paint and assessing its quality for conservation and restoration of Dancheong, as well as to produce high quality traditional paints.

• Journal of Conservation Science
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• v.30 no.1
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• pp.55-65
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• 2014

On this studyed, the Wibongsa BoGwangMyungJun BaekEuiKwanEum wall-painting was conservation of Scientific research ahead. This study carried out Grain size analysis, SEM-EDS, XRD, P-XRF, FT-IR and ultrasonic exploration for wall-painting. As a result, walls layer used to mineral particles size was mixing the medium-texture and fine texture. painting layers pigments used to base paintings was ocher, white pigments was hobun, red pigments was suckganju, green pigments was suckruk. Also BackuiKannon wall-painting walls damage reason of that was long-term physical shocks. painting layers damage was include detachment or powders. it is affected by temperature and humidity. Therefore in the future conservation of wall-paintings through scientific analysis based on such data, conservation processing is performed through the preservation and enhance the stability of the paintings as a basis for the conservation of management can be utilized.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.179-190
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• 2016

X-ray diffraction analysis, chromaticity measurement, execution and evaluation by Dancheong artisan, accelerated weathering test, and fire resistance test were conducted to test the applicability as a Dancheong pigment raw materials of Korean low grade kaolin in cultural properties. The ores that feldspar rich and composed of fine particles (< $38.1{\mu}m$) showing advantageous for the inherent purpose of the white pigment than that of high grade kaolin. And the test of whiteness, concealment force, outdoor exposure durability and fire resistance shows similar or better result than existing products (Hobun and Sanhwa jidang). In conclusion, it is expected that the use of fine feldspar rich white soil and low-grade kaolin can be used as a white pigment raw materials which have similar to better material properties and economic efficiency than existing products.