Stoneware has emerged as a popular choice in the realm of ceramics, striking a balance between sturdiness and elegance. This article delves into the composition of stoneware and its properties, sheds light on its safety for various applications, and dispels common misconceptions surrounding this versatile pottery.
The Relationship Between Stoneware and Pottery
Stoneware is a type of pottery. The term "pottery" encompasses these three main ceramic categories used to create household items. Stoneware clay is typically composed of ingredients such as fire clay, ball clay, grog, flint, and feldspar. The creation process involves shaping the clay through wheel throwing, hand building, or slip casting. After drying, the stoneware undergoes a bisque firing at around 1040°C before being decorated with glaze and kiln-fired again at approximately 1280°C.
The Color Spectrum of Stoneware
Stoneware clay bodies exhibit a diverse range of colors, including off white, tan, red, or even black. The final color of the pottery depends on the glaze applied to its surface, allowing potters to achieve a wide variety of hues according to their artistic vision.
Composition and Properties
In the creation of ceramic body stoneware, a distinctive mixture is utilized. It typically consists of fire clay, ball clay, grog (ground-up fired clay), flint, and feldspar. . By subjecting this blend to firing at different temperatures, crucial characteristics such as dry shrinkage, firing shrinkage, and porosity are determined.
Impact of Sintering Temperature
The study conducted involved burning stoneware ceramics at varying temperatures, namely 900oC and 1200oC. The results unveiled that the value of dry shrinkage stood at 2.9%. Moreover, firing shrinkage recorded 1.3% at 900oC and 3.8% at 1200oC. Porosity exhibited a reading of 10.5% at 900oC and 5.5% at 1200oC. These findings emphasize the significant influence of combustion temperature on dry shrinkage, firing shrinkage, and porosity of stoneware ceramics. Higher temperatures corresponded to increased shrinkage and decreased porosity.
Stoneware's Appeal and Increasing Demand
Stoneware occupies a unique position between stoneware and porcelain. Its allure lies in the process of vitrification, rendering it highly durable. It boasts a dense quality, natural mud color, impermeability, and a resonant, coarse sound. Over the years, the stoneware industry has witnessed rapid growth due to its eco-friendly nature, garnering favor from both domestic and international users. As the demand for stoneware rises, so do the expectations regarding its quality.
Safety Considerations
Is stoneware safe to use? The answer lies in the glazes employed by potters and ceramic manufacturers. In principle, food-safe glazes should be utilized for stoneware production. However, if any doubts persist, it is advisable to contact the manufacturer for clarification regarding the food safety of their stoneware products.
Dispelling Myths: Stoneware vs. Ceramic and Porcelain
Determining which is superior between stoneware and ceramic is not straightforward. Stoneware clay falls under the umbrella of ceramic materials, alongside earthenware and porcelain. The safety of stoneware plates hinges on the use of food-safe glazes, as the leaching of hazardous ingredients can pose risks. It is crucial to inquire about glaze ingredients and leach testing from potters, who should be forthcoming about their glaze compositions.
Contrary to common misconceptions, stoneware holds its own against porcelain. While porcelain is renowned for its delicate forms and translucence, stoneware can be fashioned into various styles. Stoneware's cost-effectiveness, lower firing temperature, and ease of handling make it an attractive choice for potters.
Safe Usage and Durability
Stoneware generally withstands oven use, as it undergoes firing at high temperatures during production. However, it is essential to avoid exposing stoneware to direct heat, as it may cause cracking. Microwave safety depends on the absorption rate of the stoneware; most matured stoneware absorbs minimal water and is therefore suitable for microwaving. While stoneware can break if subjected to sudden impacts, it remains highly durable under normal handling.
To summarize, stoneware embodies a rare fusion of durability, aesthetic appeal, and versatility. With its precise composition, refined firing techniques, and meticulous attention to safety, stoneware continues to enchant pottery enthusiasts worldwide. Whether utilized for culinary endeavors, showcased as exquisite decorations, or seamlessly integrated into everyday life, stoneware remains an esteemed form of ceramic artistry that holds timeless allure.
Source:
https://ojs.unud.ac.id/index.php/buletinfisika/article/view/36136
https://thelittlepotcompany.co.uk/blogs/pottery/stoneware-pottery
Yanrong Cai and Rui Li 2019 IOP Conf. Ser.: Mater. Sci. Eng. 490 022080