Investigation of Ultrasonic Vibration Influence on the Fineness and Pigments of Terra Sigillata Engobe

Document Type : Original Article

Authors

1 Department of Handicraft, Faculty of Art, Alzahra University, P.O. Code: 1993893973, Tehran, Iran

2 Department of Industrial Design, Faculty of Art, Alzahra University, P.O. Code: 1993893973, Tehran, Iran

10.30509/jcst.2026.167779.1282

Abstract

Terra sigillata is one of the oldest and most lustrous non-glazed ceramic surface coatings, yet its traditional preparation is time-consuming and inefficient. on the other hand, high frequency and low amplitude of ultrasonic vibration could improves coating quality. This study investigates the effect of ultrasonic treatment (sonication) of secondary clays as an alternative to conventional methods of producing terra sigillata. The research examines whether ultrasonic processing of the engobe can improve engobe particle quality, influence color characteristics, and accelerate or modify the preparation process. An experimental laboratory approach was performed, and the validity of the results was evaluated using field emission scanning electron microscopy (FE-SEM), color measurement, and EDS. Findings indicate that ultrasonic treatment significantly reduces the time required to obtain a usable engobe compared to traditional settling methods and decreases material waste. In other words, this technology eliminates the required rest time that redues preparation time about 72 hr. Also, all of sonificated engobe could be used without any wastage. The particle size is reduced from above 1µm to under 200 nm. Colorimetric analysis further shows that combining ultrasonic processing with careful selection of the settled fraction produces desirable color variations and enhanced visual uniformity ( . Overall, the results suggest that sonication can serve as an effective method for improving efficiency and controlling surface qualities in the preparation of terra sigillata and related ceramic coatings.

Keywords

Main Subjects

References

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