Reliable irogane alloys and niiro patination—further study of production and application to jewelry

Japanese metalworkers use a wide range of irogane alloys (shakudo, shibuichi), which are colored with a single patination solution (niiro eki). This approach allows different alloys to be combined in one piece and patinated, producing a multi-colored piece of metalwork. At present the niiro patination process is unreliable. In this study we develop a deeper understanding of the effect of patination solution ingredients on color. We have tested a synthetic niiro solution, comparing the color results with traditional niiro solution patination. Surface products have been analyzed to determine how they are influenced by both the niiro solution and cleaning procedures during patination. A large range of shibuichi and shakudo alloys have been produced to determine the full color pallette. This work also explores the use of alternative processes for the patination of irogane alloys, examining the effect of laser marking and anodizing on irogane alloys

Japanese irogane alloys and patination – a study of production and application

Japanese metalworkers use a wide range of irogane alloys (shakudo, shibuichi), which are colored with a single patination solution (niiro). This approach allows different alloys to be combined in one piece and patinated, producing a multi-colored piece of metalwork. At present the production of irogane alloys and their patination is an unreliable process. This study aims to develop reliable alloy production and a safe, easy-to use and repeatable patination process using standard ingredients available from chemical suppliers. The study has examined the production of shakudo and shibuichi alloys, characterizing the alloys produced by casting into cloth molds in hot water, into steel molds, and produced using continuous casting. The influence of traditional polishing methods was assessed using surface texture (Sa) measurements. Traditional rokusho, an ingredient of the niiro solution, was analyzed by XRF and XRD. Niiro patinated surfaces on a range of alloys were examined using XRD and L*a*b* color measurements.</p

The use of friction stir welding for the production of Mokume Gane-Type materials

Mokume gane is a highly desirable and unique decorative material but production is difficult at both workshop and industrial levels. This paper describes a novel method for producing mixed metal, multi-colored, layered materials using friction stir welding (FSW) and compares the results with mokume gane made by a number of different conventional methods. FSW was invented in 1991 by TWI, a UK-based research and technology organization, and has found widespread use in the joining of aluminum and, more recently, steels. By adapting FSW it has been possible to successfully bond many layers of dissimilar metals such as silver, copper and brass, etc., while simultaneously producing unique patterns in the metal, minimizing further processing, reducing waste and potentially lowering costs. The technique avoids many of the problems experienced in workshop production, e.g., melting of lack of bonding, while allowing production of small, customized ingots and mass production of large sheets, with up to several square meters possible

Radishes or isothiocyanates? A search for control between art and science

This paper addresses a five-year interdisciplinary research collaboration between a silversmith and a material scientist. The paper describes two projects carried out by Dr Coilin O’Dubhghaill (Art and Design Research Centre) and Dr Hywel Jones (Materials and Engineering Research Institute) at Sheffield Hallam University between 2007–2012. The first of these projects addressed problems of reliability and control in metal patination. In the Japanese metalwork tradition there is a unique process used to produce multi-coloured metalwork. A range of metals and special alloys are combined in a piece of metalwork and patinated using a single solution – the niiro solution. This approach allows the designer to incorporate a wide palette of colours in a piece of metalwork. However, difficulties in producing the alloys and controlling the patination process have limited the possibilities for application of these materials. The collaboration brought together the expert knowledge of a craftsperson and a materials scientist in a search for improved alloy production and patination process control. The study led to improved understanding of casting techniques for alloy production, the development of a non-proprietary synthetic niiro solution, and overall enhanced process control. The research was disseminated through lectures and papers in journals and international conferences, and through exhibitions of artwork produced as a study of practical applications. A second ongoing research project looks at new techniques for the production of Mokume Gane, a multi-coloured metal laminate used in the jewellery industry. Mokume Gane is a highly desirable and unique decorative material, but production is difficult at both small workshop and industrial levels. The research investigates a novel method for producing mixed metal layered materials using friction stir welding (FSW) and compares the results with mokume gane made by a number of different conventional methods. FSW was invented in 1991 in the UK by TWI and has found widespread use in the joining of aluminum and, more recently, steels. By adapting FSW it has been possible to successfully bond many layers of dissimilar metals, while simultaneously producing unique patterns in the metal. This minimizes further processing, reducing waste and potentially lowering costs. The technique avoids many of the problems experienced in traditional workshop production e.g. melting or lack of bonding, while allowing production of small, customized ingots and mass production of large sheets, with up to several square meters possible. The research builds on the traditional craft knowledge of the silversmith, developing novel methods and materials through the use of cutting edge processing techniques. The paper describes the practices and outcomes from the above projects and the kinds of new knowledge such research can yield. The paper also reflects on how the research was structured and carried out. Through interviews with the participants, the experience of the collaborators is examined and the difficulties and advantages of this type of research collaboration are considered and explored.</p

Mokume Gane a reinvention

Japan has a unique range of traditional metalcraft processes that are still practiced today. Two of these surviving processes have been studied extensively with the aim of developing industrial applications, the irogane alloy and niiro patination process, and the laminated decorative metalwork process known as “mokume gane” or wood-grain metal. In particular, mokume gane has made the crossover from craft process to industrial process. This paper examines the historical background and contemporary development of the mokume gane process

Friction-stir patterned metal laminates

Mokume gane is a high value, decorative laminate material used in the jewellery industry. Production of mokume gane is difficult and expensive at both small scale and industrial levels. This research investigates a novel method for producing a mixed metal layered material, similar to mokume gane, using friction stir processing (FSP). By adapting FSP it has been possible to successfully bond many layers of dissimilar metals such as silver, copper and brass, while simultaneously producing unique patterns in the metal. This approach minimizes processing, reduces waste and potentially lowers costs. The technique avoids many of the problems experienced in standard mokume gane production, such as melting or lack of bonding. It is possible to manufacture both small customized ingots, and to mass produce large sheets up to several square meters in size. This project is a collaboration between SHU and Rotary Engineering UK funded by TSB and Innovate UK.</p

Mikana: new forms of mokume gane

This paper addresses the ongoing development of a new form of mokume gane. The mokume gane process has its origins in 16th century Japanese metalwork, and has been used in the West since Tiffany & Co, and Christofle adopted the process in the 1870’s. Research in the 1980’s enabled the production of precious metal mokume gane jewellery and more widespread commercialisation of production. The paper discuses the historical background of mokume gane and describes an interdisciplinary project between researchers and designers from the jewellery and silversmithing field, working in collaboration with material scientists and engineers, that led to a new form of mokume gane production techniques. The paper reflects on the collaboration and how the research was carried out, and the subsequent formation of a spinout company “Mikana” to commercialise the new material

Objets, Mes Amis at Artmonte-carlo

A special exhibition of furniture and objects held during the Artmonte-carlo fair, curated by French designer Martine Bedi

Irogane Alloys and Niiro Patination samples

This research into Japanese irogane alloys and niiro solution patination techniques presents new information on their composition and reliable production. It was funded by an AHRC Fellowship in the Creative and Performing arts (AH/E005497/1), two AHRC research grants (AH/F012101/0 and AH/H020624/1) and a grant from the Great Britain Sasakawa foundation. Niiro (boiling colour) refers to the hot copper salts solution used to develop patina on the irogane (coloured metal) alloys. The research was initiated by O’Dubhghaill following a six-year period studying in Japan with traditional metalworkers and the realisation that the specialist patination experts there also found the process difficult to control. A systematic method of testing, analysing and recording the traditional materials and methods was undertaken to quantify alloy and niiro compositions, conditions of immersion, and colours produced. Collaboration with material scientist, A.H.Jones enabled controlled alloy production and a synthetic niiro solution, using standard laboratory-grade chemicals to be developed. These were successfully tested and shown to produce colours comparable with traditional solutions in a consistent manner, eliminating uncertainty in the process and allowing better production control. This material and process research is presented here as physical test samples supported by related published papers. Japanese Irogane Alloys and Patination - A Study of Production and Applications (2009) and Reliable Irogane Alloys and Niiro Patination—Further Study of Production and Application to Jewellery (2010); were presented at the 2009 and 2010 SantaFe Symposium on Jewellery Manufacture Technology. Related articles were published in the MJSA Journal (2010) and The Goldsmiths Company Technical Bulletin in (2010), and presented at the Association for Contemporary Jewellery, Crossings Conference, (2010).Guest Lectures include Tokyo University of the Arts, Tokyo (2010),Tama Art University, Japan (2010) and the National College of Art and Design, Dublin (2010)