A Study On Multi-layer Glaze Technology Of Longquan Celadon In Southern Song Dynasty

Longquan Celadons are famous for their glaze as thick as cream and as smooth as jade.The thick glaze is its typical feature.The development of the technology of Longquan Celadons is always explored and practiced around the technology of thick glaze.We can say that the history of the development of the technology of Longquan Celadons is essentially the history of the development of the technology of thick glaze.The technology of multi-layer glaze is the core of the technology of thick glaze and the change of Longquan Celadons from the feature of thick body and thick glaze to the thin body and thick glaze.In this way,Longquan Celadons have reached their peak.In terms of material aesthetics,they approach the key technology of the ideal “jade quality”.This paper takes Longquan Celadons of Southern Song Dynasty with the structure of multi-layer glaze as the research object,and studies the development process,technology composition,process influence,and other aspects of the technology of multi-layer glaze of Southern Song Dynasty with literature review,identification and comparison of material objects,process experiment,and other methods based on the research results of previous scholars.It is found in the study that the emerging and development of the technology of multi-layer glaze is clear and closely related to the development of elutriation,glaze making,glaze application,bisque firing,glaze firing,and other technologies.Under the conditions of the multi-layer glaze process,the strength of the first layer of glaze is the highest among all the layers of glaze.It is a prerequisite for different layers of glaze to obtain the corresponding strength before the second time of glaze application for the implementation of multiple times of glaze applications.The structure with the superposition of glaze layers caused by the technology of multi-layer glaze has an important impact on the color of glaze,the formation of jade texture,cracked glaze,etc.The research results show that the technology of multi-layer glaze consists of multiple processes and technologies.It is very local and it is a self-contained process technology system.In the process of multiple glaze applications,several times of bisque firing of the body with glaze application is the most effective way for each layer of glaze to obtain the corresponding strength before the second time of glaze application.With the increase of the proportion of porcelain clay in the glaze,the raw glaze can meet the requirement for the strength of multiple times of glaze applications in the process of bisque firing.The differences in the glaze layers of the multiple-layer glaze of Celadons from Longquan Kilns have a big impact on their glaze.First,the color of the middle layer of the glaze layer is relatively dark,so the overall glaze color is deeper and calmer.Second,the density of the middle layer of the glaze layer is relatively high so that a lot of bubbles are kept in the glaze,the diffuse reflection of the light emitted into the glaze layer is caused,and the jade sense of the glaze is increased.Second,the shrinking percentage of the middle layer of the glaze layer is greater than that of other glaze layers.When it shrinks and releases the tensile stress,the extrusion tension is also applied to the glaze on the surface layer accordingly,so that it continuously expands and cracks and it is easy to form the cracked glaze effect similar to the form of ice cracks.Combined with the repeated and successful experiments of multiple times of glaze applications,the following conclusion is concluded.In the process of multiple times of glaze applications,for Longquan Celadons of Southern Song Dynasty,several times of bisque firing of the body after glaze application are required and different bisque firing temperatures are used according to the demand for the strength of each glaze layer.The formula of glaze used in the first layer of glaze is different from that of other glaze layers.The emerging of cracked glaze with the form of ice crack on the glaze of Longquan Celadons of Southern Song Dynasty is directly related to the structure with the superposition of glaze layers caused by the multi-layer glaze process.It is a special effect formed under specific process conditions.There should be no specially prepared glaze with ice cracks.