Developing Ceramic Textured Matt Glazes Using Omani Plant Ash: The Contributions of Art Education Teachers

It is widely known that ready-made glazes are hugely expensive, in spite of their widespread availability in Oman. Most students of ceramic art, at various levels of education, depend on foreign materials rather than local materials, which has resulted in high production costs. As an environmentally diverse country, Oman has great potential to take advantage of local crop waste plant waste by using it to make attractive ceramic glazes. Ann experimental study conducted at the ceramic studio in Sultan Qaboos University (SQU) led to the development of some excellent recipes for ceramic glazes using 20% to 30% ash. This study has helped to convert Omani plant waste into textured matt ceramic glazes, which are otherwise expensive to procure for educational and commercial purposes.


Introduction
One of the most significant current discussions in ceramics and pottery researches is using environment waste materials in developing their creative pottery.Most researches in developing abilities of art education teachers to take advantage of waste materials in teaching process have only been carried out in a small number of studies.So far, however, there has been little discussion about using trees waste materials including their ashes in specific in teaching ceramics courses in Oman.Plant ash is very useful for making unique glazed surfaces on pottery; therefore, it has become important in art-education schools and ceramics studios in recent times.The organic elements found in plant ash supply potters with calcium, potassium, magnesium and sodium, which are essential for making unique glazes.In fact, these elements supply potters with the proportion of fluxes and hardeners and these materials are necessary for making glaze recipes.Historically, Phil Rogers (2003) states that ash glazing began in China in about 1500 BC, during the period of the Shang Dynasty.In approximately 1000 BC, the Chinese became conscious that wood ash was covering the piece.Metcalfe (2008) cites Rogers, who mentions that the Chinese first developed ash glazes for stoneware about 3500 years ago, when the technology of their kilns improved sufficiently to enable the kilns to reach high enough temperatures to fuse these types of glazes.Metcalfe also states that it was more than 2000 years before this knowledge reached Japan and Korea, where ash glazes were subsequently produced (2008).In 1991, Rogers employs standard blending methods to test ash glazes containing wood and coal ashes.De Montmollin (1997) contributed in studying ash glazes preparation, composition and testing of a wide variety of wastes plant ashes from straw to lavender to wood.After one year, Tichane (1998) published a book included a wide variety of ashes and acknowledges the use of washed and unwashed ash in glazes and this contribution considered as a jump in the studying ash glazes techniques.It is worth mentioning that Rogers's second edition of the same book which published in 2003 added wider range of examples of contemporary ash glazed works and his contributions were very valuable for ash glazing researches.Considering Oman's environmental diversity, its plants differ from one area to the next.Therefore, this experimental research examined the effects of more than 30 types of Omani plant ash when a percentage is added to textured matt glazes.After very intensive experimental research including lab testing, this research presented a proved ash glazes recipes belonged to Oman environment.This exclusive contribution helped art education teachers and ceramics artists to develop their artworks by using their environment waste materials.
This paper has been divided into six parts.The first part deals with research methodology (experimental research).And the second part will cover preparing and selecting samples of plant ash.The third part will present the XRD analysis including detecting minerals and chemical formulas.The fourth part will present the researcher's calculation of glaze recipes for testing.The Fifth part will introduce the list of tests which conducted in the glazing lab.And finally, the last part will assessing the tests to explore their qualities for applications.

Research methodology: Experimental research
A considerable part of this research is devoted to answering the question: To what extent can Omani plant waste contribute to the production of textured matt ceramic glazes?By using laboratory tests, this study has revealed that ash from some Omani plants can make a significant contribution to local textured matt glazes that are used to create a surface design, such as on tiles, handicrafts and a range of artistic products.In the SQU ceramics lab, substituting different materials when creating glaze recipes gives the ceramicist many subtle differences in textures and colours.In fact, the possibilities are endless with any glaze; the ceramicist just needs to focus on developing the characteristics that he or she wants.Aside from being cost-efficient, these glazes are also more aesthetically pleasing than ordinary commercial glazes.The ceramic tiles used for the experiments in this research were made of white clay (PotteryCrafts white earthenware clays) and bisquette-fired at a low temperature to guarantee the absorption of the glaze sample.

Preparing selected samples of plant ash
Omani villages produce many kinds of agricultural waste.This waste is produced mainly by farmers and by industries related to agricultural activities.It must be suitably treated in order to be used correctly.
Agricultural waste collected from several different areas in Oman included 27 different types of plants (Table 1), which were selected to be examined in this research.The collected samples of each selected plant were burned in metal containers to minimize the risk of any impurities from the ground contaminating the sample.Despite precautions taken during the burning and collection stages, the remaining ashes unavoidably include some undesirable impurities.These need to be removed in order to make a very fine powder that is appropriate for mixing with glaze samples.Each type of ash was washed in a large plastic container that was half filled with ash, and then filled to the top with clean water.The ash was then allowed to settle.This process was repeated several times.The ash was then extracted and, once dry, it was sieved using a ceramic 40-mesh sieve.
In order to guarantee that each sample would be large enough to create the many test tiles throughout the research, the researcher produced at least 500g of pure powder for each sample.The collected ash samples were then stored in plastic containers and labelled.All the information related to each sample was documented in order to be ready for experimentation in the SQU ceramics laboratory.

XRD analysis: Detecting minerals and chemical formulas
In order to explore how the mineral content of the selected ash samples plays a role in creating special textures in ceramic glazes and slips, the researcher sent samples to be tested using an X-ray powder diffraction (XRD) analysis system.The XRD is "a rapid analytical technique primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions" (SERC, 2016).
The reports of the collected data for the selected samples contained hundreds of pages, including extensive data and figures; however, the most important data were provided in the tables of minerals and chemical formulas.To illustrate, the test report for the ash sample of the Calotropis Procera tree includes full data about the minerals and chemical formulas it contains, as shown in table 2.

Calculation of glaze recipes for testing
One of the most important points to be considered at this stage was that the quantity of ash in each recipe should be as high as possible in order to guarantee its influence on the final result.Therefore, it was essential to keep the other number of ingredients in the recipes to a minimum.The researcher and his assistants at SQU used various methods to develop different recipes; this was compulsory, because this project aimed to test the ashes of 27 types of plants.Therefore, testing methods, including the line blend (blending two recipes), triaxial blend (blending three recipes), and tetrahedral blend (blending four materials), were used by my assistants within the research period (four months).These methods have been used in many ash-glazing research projects, such as those of Metcalfe ( 2008), Shamsu Mohamad (2005), (Birkhimer, 2006), andRabena (2008).Because the line blend method was preferred, we mainly used this method in this project.

The list of tests
More than 1,000 test tiles were produced for this research.Each type of ash was examined in more than 40 tests (or recipes).Consequently, it was essential to categorize the outcomes of these tests and classify them according to artistic and technical standards for ceramics.Nevertheless, it is worth remembering that the main objective of this research is to develop textured matt glazes to be used mainly for sculptures in art schools and by small enterprises.In addition, it was important to compose a base glaze recipe, as this would allow us to observe the differences between the types of ash to be tested.Therefore, we developed the base matt glaze recipe shown in table 3.

Conclusion
This paper has given an account of, and the reasons for, the widespread use of ash in developing glazes for ceramics.Specifically, this study has helped to convert Omani plant waste into textured matt ceramic glazes, which are expensive to procure for educational and commercial purposes.One of the most significant findings to emerge from this study is that when ceramicists used a proportion of 20% to 30% ash, this led to the development of excellent recipes for matt glazes for ceramics.The evidence from this study suggests that craftspeople and ceramic artists can develop their final outcomes by creating very special textured matt glazes for their artworks in order to replace commercial glazes.
This study contained a thoughtful finding with sound recommendations for the development of ceramic teaching as part of art education developments in Oman.So, here follows the set of recommendation based on what is believed to be the most important issues that need to be addressed to use ash glazing in art education.First, it is essential to enforce the new art education's teachers to explore plants wastes from their regional environment to use them in developing their students' artworks to avoid using expensive imported glazes.Second, teachers from different environments and territories must exchange their successful recipes to be used later by different schools.

Figure 1 :
Figure 1: Images of some tests

Table 1 :
The list of 27 different types of plants from several different areas in Oman

Table 2 :
Chemical formulas in the tested sample of Calotropis Procera

Table 3 :
The recipe of base matt glaze used in experiments

Table 5 :
Rubric to assess the final results