First of all, the positions of colors are different.
Glazed porcelain has a colored glaze and a raised feel.
The color in glaze is sandwiched between two layers of glaze, which is a veritable porcelain with color in glaze.
Under-glaze porcelain, the color is under the glaze, never fades, and it is smooth and flat.
Second, the process is different.
Over-glaze colored porcelain is a variety decorated with colored paintings on the glazed surface of fired porcelain.
There are two ways to make colored porcelain in glaze: one is to add some pigments or pigments to the glaze and then fire at high temperature. Second, the glazed green tire is first fired at 800℃ and then painted, and then sprayed with a thin layer of glaze and then fired at high temperature.
Under-glaze color is a kind of porcelain which is coated with pigment, glazed and fired at high temperature at one time.
Extended data
There is an obvious difference between underglaze colored porcelain and underglaze colored porcelain, that is, the colored decorative part of underglaze colored porcelain does not protrude the glaze, and some even droop. This is because the colored substances coated on the tread are adsorbed, and the glaze water is naturally leveled under air pressure when covering the glaze. In-glaze painter adds a layer of pigment to the flat glaze, which increases the total thickness of the decorative part.
In this way, there will be two different shooting effects:
1. If the glaze surface with low viscosity and high fluidity is painted at high temperature, the glaze surface of the colored ware will be even and smooth without bulging after the pigment sinks into the glaze under the action of high temperature melting and atmospheric pressure.
2. If the color is applied on the opaque glaze surface with relatively high glaze juice concentration and high viscosity test at high temperature, the fluidity after melting is small, and the kiln temperature can meet the requirements of vitrification of the base porcelain and glaze surface during firing, but the glaze surface is not easy to flow evenly, so the pigment and its surrounding glaze surface are more or less convex.
References:
Baidu encyclopedia-in-glaze color