Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Development of gold-bronze metallic glazes in a clay-based system for stoneware bodies Keriman Pekkan a, ⁎ , Hasan Başkırkan b , Münevver Çakı c a Dumlupınar University, Faculty of Fine Arts, Department of Ceramic and Glass, Kütahya, Turkey b Mimar Sinan Fine Arts University, Faculty of Fine Arts, Department of Ceramic and Glass Design, İstanbul, Turkey c Münevver Çakı, Anadolu University, Faculty of Fine Arts, Department of Ceramic Arts, Eskişehir, Turkey ARTICLE INFO Keywords: Gold-bronze Metallic glaze Color Stoneware ABSTRACT In this study, a triaxial glaze system consisting of red clay, kaoline, quartz, MnO, CuO and CoO is systematically developed to produce gold-bronze raw metallic glazes for stoneware bodies. At first, all of the glazed samples in the developed system were fired in an electrically-heated kiln at 1160 °C. Then, the selected successful gold- bronze metallic glazes were applied onto 3-D forms of stoneware bodies and fired at the same conditions. Microstructural characterizations of the glazes are done with scanning electron microscopy (SEM) and energy dispersive x-ray analyses (EDS). This study revealed that triaxial blending of the ceramic raw materials is a beneficial method for glaze production and gold-bronze surfaces are obtained in glazes G 9, G 26, and G 34. It is observed that chemical composition of the glazes directly influence the color and the amount of CuO is more significative than MnO for achieving gold-bronze effect. 1. Introduction Oxide coatings are commonly used for ceramics with a high dec- orative effect and metallic glazes are one of the most attractive glaze types in ceramic industry. They enhance the surface aesthetic properties with a brilliant metallic shine as lusters usually do [1,2]. Bronze luster on the surface of a glaze can be achieved with chromium and lead com- pounds in a special reduction firing. Bronze-effect glazes can be obtained in oxidized stoneware and porcelain using the fluxing action of manga- nese oxide with or without copper oxide, feldspar and/or clay [3]. Reduction luster is a highly decorative traditional glazing tech- nique. However, it is necessary to control the furnace temperature, atmosphere and time during the reduction process in order to achieve successful results and this is quite difficult for traditional kilns [4]. Therefore, reduction technique is not appropriate for industrial pro- duction in terms of instability surface properties and generation of undesirable gases [5]. Nowadays, metallic glazed products exhibit many innovations for the decoration of ceramics, compared with decorations made by adding noble metals, reduction techniques or specific firings at lower tem- peratures (third fire) [6]. Generally, metallic glazes are produced using different raw materials such as clays, feldspars, Al-based phosphates, ceria, metallic oxides and frits [1,7]. As opposed to fritted composi- tions, raw glaze is a cost effective and time consuming alternative for ceramics [8,9]. Golden or bronze metallic effect is generally obtained by luster technique by using noble metals or lead in glaze compositions as well as introducing high amounts of frits in glaze batches [2,10]. Unlike luster glazes, it is necessary to use a different preparation method for metallic glazes and that the final surfaces exhibit the characteristics of the chemical ingredients [2]. Among all clay body types with artistic potters, stoneware is the most important with its fired strength and the character of the finished product. Firing atmo- sphere, inherent metallic oxides in clay and chemical glaze composition are the main factors that affect the colors of the fired stoneware objects [11]. When developing a new glaze composition, it is of a great im- portance to perform a systematic study which is most effectively en- sured using blending systems and constructions. There are different types of methods such as line blend, triaxial and quadraxial blends. Triaxial blending of the ceramic raw materials is an important process, mainly used to create a new glaze. They are very useful systems for mixing raw materials, glazes, or colorants [12]. Generally, they give thoroughly comprehensive scans of mixtures including two, three and four components [13]. In the present study, the gold-bronze raw me- tallic glazes are designed by employing a triaxial blend system in order to explore the combinations of selected components that are suitable for stoneware decorations. For this purpose, a glaze system consisting of red clay, kaoline, quartz, MnO, CuO and CoO is developed and char- acterized in terms of surface properties and microstructure. https://doi.org/10.1016/j.ceramint.2017.12.064 Received 13 November 2017; Received in revised form 8 December 2017; Accepted 8 December 2017 ⁎ Corresponding author. E-mail address: keriman.pekkan@dpu.edu.tr (K. Pekkan). Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2017 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Pekkan, K., Ceramics International (2017), https://doi.org/10.1016/j.ceramint.2017.12.064