| China is the biggest country for producing architectural and sanitary ceramics, also is the biggest consumer market. However, the economic benefit is not as good as other countries. One of the problems is the quality of glaze surface including pinholes and pits. The contaminants such as dirt, bacteria, are easily settled on the flaws and hazard the helth of user. To reduce the surface roughness of glaze is a better way to destroy the site for contaminants settling and is also a promising work for developing the quality of sanitary ceramics.Feldspar, quartz, kaolin clay, calcspar and dolomite were used as raw materials. The super-smooth glaze was prepared by normal procedure. The effects of the quality of glaze slip, the properties of glaze at high temperatures, and the microstructure of glaze layer on surface roughness were discussed.The quality of glaze slip is the key factor affecting glazing process, also has an important effect on glaze quality. The more content of frit in the glaze, the better quality of glaze. The surface roughness (Ra) of glaze is less than 10nm when the content of frit is more than 60wt%. The glossiness of glaze is more than 110% with the content of frit more than 80wt%. The surface roughness decreases with the reducing of particle size. The surface roughness is less than 10nm when D90 is between 4.07.5μm. The desired samples are obtained using the glaze slip with a density of 1.51.6 g·cm-3 (for green body) and 1.61.7 g·cm-3 (for bisque body). Glazing procedure is favoring when the fluidity of glaze slip is 810(Pa·s)-1. The viscosity of glaze slip is decreasing, and then increasing with the addition of carboxymethylcellulose (CMC). The glaze slip is well suspended with 0.3wt% CMC.The high temperature properties of glaze, such as viscosity, surface tension and wetting angle, play important parts in the glaze smoothness. The glaze surface with low surface roughness was gained when lgηis between 2.65～3.15, surface tension between 350～380 m(N·m)-1, and the wetting angle of glaze melt on body between 30～15°. Densification of body and decomposition of some raw materials at high temperature are the main reasons of bubble formation in the glaze. The nearer the glaze to surface, the bigger the bubble will be. The surface is obviously irregular when the bubble diameter is bigger than 20μm, and the surface is smooth when it is smaller than 10μm. Crystals were precipitated when the holding time at high temperature is long and the cooling is very slow. The crystal size is varying with the holding time and cooling...
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