Teach you how to identify porcelain through the defects in glaze color

2022-07-13 0 By

Porcelain in the production process, there will be a variety of problems, today to take a look with you at the porcelain glaze defects, and how to help us identify these defects.One of the defects of glaze.Is the glaze layer in the firing process due to the chemical reaction of the glaze bubble can not be completely discharged and formed a “glaze disease”.The bubbles in the glaze layer are generally small, and the bubbles on the surface of the glaze layer are slightly larger, which are easy to be broken by friction and form black defects after pollution.One of the defects of bristle and eye porcelain glaze, also known as “pinhole”, “pig pore”.The glaze has tiny pits that look like leather pores.This is due to some organic matter and some impurity content in the glaze is more, the preheating and burning heat up too fast, the temperature difference is big, make these material failed to fully oxidation decomposition at oxidation stage, continue to break down and to restore and high temperature phase, the reaction gas evolution glaze, when glaze of high temperature viscosity, liquidity is poor,Bubble burst in the glaze formation of the small hole can not be covered by the glaze, that is, the formation of small pores.This is one of the notable features of the glaze of Yongle and Xuande porcelains in the Ming Dynasty.Orange peel porcelain glaze defects, also known as “orange glaze”.Refers to porcelain glaze is not smooth, similar to orange skin texture phenomenon.The reason is that the surface dressing of the body is not good, and the glaze layer is too thin to make up for the uneven body.Or because the glaze is not fine enough, the glaze slurry is too thick, the glaze slurry is not evenly distributed on the surface of the body.This phenomenon is also easy to occur when glaze viscosity is too high in high temperature melting state.It is commonly seen on Ming Dynasty Yongle and Xuande porcelain.One of the defects of speckled enamel.Spots on the glaze that are different in color from the glaze.The reason is that all kinds of minerals in glaze juice produce chemical reaction in the firing process, but also because of the embryo itself washing impure or unclean in the sagger.The most common are dark brown spots.Modern imitation of su ma from green rolling glaze porcelain glaze defects, also known as “contracted glaze”.Refers to the glaze to the periphery of the roll, the formation of the middle glaze exposed fetal bone.There are many reasons for the formation: the glaze is affected by surface tension, the blank tire is too wet during glaze application, the high temperature viscosity of the glaze is too large or the blank surface is oily, the kiln workers have sweat on their hands, the moisture in the kiln is too much, the blank surface is wet, and the local glaze is rolled up and fallen off after heating.One of the glaze defects of porcelain, also known as “leakage glaze” or “short glaze”.Namely porcelain surface local lack glaze.There are many reasons for lack of glaze: poor adhesion of glaze paste, thick glaze layer, dry off;High temperature viscosity of glaze is too large, and the blank formula does not adapt to cause the glaze layer curled up;Glaze surface oil and dust;Immersion glaze, glaze slurry is not filled with the whole device;After glazing the body, the local glaze will fall off carelessly;Glaze slurry water greasy;The water content of the blank body into the kiln is too high, and the water vapor in the kiln is too much during firing, which makes the blank glaze stratified in the middle and causes the glaze layer to peel off.One of the defects of clay enamel.There are sand grains on the bottom foot glaze.In order to avoid adhesion when loading the kiln, the sand layer is mostly laid on the kiln bed. Under the action of high temperature, the sand particles are bonded with the glaze juice at the bottom of the kiln.At the end of the Ming Dynasty, chongzhen people kiln products from time to time sticky sand phenomenon.Smoking is also known as “string smoke” and “smoking”.A defect in ceramic products.Refers to the finished product part or all appear gray black, brown.”Tao Ya” cloud: “fine glaze through fire, into its color, smoke fume, but such as splash-ink, it is called smoke.”There are many reasons: improper firing operation, resulting in carbon deposition in the blank glaze, before the glaze melting, not eliminated by oxidation;Too much water in the kiln body;The sagger fires and the smoke is sprayed directly onto the products.One of the defects of the ceramic glaze.Irregular cracks appear on the glaze surface, but the body itself is not cracked.The main reason is that the expansion coefficient difference between tire and glaze is too large, especially the expansion coefficient of glaze is too large, the glaze layer is too thick, and the cooling speed is too fast in the temperature range of 750℃ – 550℃ during the cooling stage.Clever use of this defect can also become a special decoration of porcelain glaze.Song Dynasty elder brother, official kiln porcelain on the opening is caused by artificial control.And the use of old utensils due to the impact of the external environment and corrosion itself, will also appear small chip grain.Buckwheat glaze defects, also known as buckwheat point.On the glaze appeared a piece of tiny dark brown stars, like buckwheat skin.The reason is that there is flying dust attached to the glaze surface at high temperature in the kiln, and this phenomenon also occurs when the glaze contains impurities.Buckwheat fields are more likely to appear in secondary burning utensils.One of the defects of a porcelain glaze.There are pieces or pieces of porcelain glaze off the phenomenon.One is to strip the glaze before firing, and the other is to strip the glaze during firing.There are many reasons for stripping glaze, glaze and billet expansion coefficient is not suitable;There are also glaze layer is too thick or heating up too fast when firing;Or the body glaze before sticky mud, dust, oil juice;Even sometimes makeup soil will also make glaze tire union is not firm and peel glaze.Peeling glaze phenomenon to early celadon is more common, yixing Ming imitation jun also have.Deglazing is also known as peeling, one of the defects of porcelain glaze.It is a common disability that glaze layer falls off to different degrees and exposes fetal body.Deglazing reasons are more complex, such as glaze by salt, alkali, acid corrosion for a long time;Or by soil invasion and water after the soil.It is easy to deglaze when sintering temperature is not enough.One of the glaze defects, also known as damage glaze, refers to the glaze and other objects caused by friction damage.Long-term use will cause this phenomenon, if it is painted porcelain will make the pattern blurred.One of the defects of the collapse glaze.Porcelain is hard after the glaze layer crack “from the bone”, most of the broken glaze surface smooth not falling off.The cause was a collision with a hard object when excavated.The grain of the collapse glaze extends radially.Tear mark one of the glaze defects.When porcelain is fired into the kiln, the glaze juice flows down due to excessive fluidity and becomes wax tear or glass bead shape protrusion in the lower part of the utensils.These drooping drops of glaze are often called tear marks.This phenomenon can be seen in porcelain products before the Tang Dynasty.Since then, tear marks have been regarded as an important feature of dingyao in the Song Dynasty.One of the defects of chisel enamel.Refers to the size of pottery glaze pits damage.If the glaze layer of qing dynasty kiln porcelain is thicker and more open with pieces, if the cotton cloth is often used to wipe it, the small sharp corner at the intersection of pieces will be lifted or removed, leaving triangular pits.Scratch one of porcelain glaze defects.Refers to the glaze table or painted surface scratches by hard objects left traces, porcelain is used for a long time and hard objects inadvertently touched by scratch.One of the defects of soft channel enamel.Refers to the small silk lines on the glaze due to long friction.It is usually found on ancient artifacts and is not easy to find without careful observation.This kind of soft channel is different from the friction mark in the forgery technique, it often appears in the convex part which is most often contacted and rubbed in the daily use of implements.When the new machine is used, the whole machine is rubbed with soft linen, which makes the damage of the soft channel extremely unnatural.One of the defects in the glaze.Refers to the loss of luster of the glaze.Due to long-term wear and tear, or due to burial caused by soil invasion and flooding will make porcelain surface loss phenomenon.One of the defects of water – alkali glaze.The phenomenon is that the glaze surface of the utensils condenses with gray and white patches.This is because plain glaze ware has been immersed in wet soil for a long time by alkaline impregnation, alkaline material attached to the surface of the device.One of the defects of water rust glaze.Because of long-term soil burial or water immersion, the physical change of the utensils makes the surface of the utensils appear gray, yellow, iron red, copper green and other color spots.The rust is very thin, just a faint patch of color, which can be washed away with an acid.One of the defects of clay rust glaze.Implement expression sticks the earthy scar that has the color such as ash, yellow, earthy red solidify.Soil rust is long-term immersion in the wet soil, clay bonded in the rough surface of the place caused by the general firm, not easy to peel down.One of the defects of soil erosion enamel.The glaze or painting is corroded by the soil for a long time, making the local glaze surface tarnish.Soil erosion is different from rust in that it not only corrodes the glaze, but also penetrates part of the fetal bone.Fire has two meanings.One of the defects in a glaze.The second time the utensils were burned led to color glaze changes, such as blue and white black, yellow glaze green, blue and white glaze wrinkles, and glaze with fire glaze fusion flow marks and clay on the gray, black dust.A defect caused by repair.In order to fill the local color or glaze, again into the kiln baking, although the partial temperature is suitable, but the original glaze will be damaged to varying degrees.One of the defects of colored porcelain painting.Mutilation refers to the mutilation of painted work.There are partial or total injuries.Long period of water immersion, acid and alkali corrosion or improper wipe will lead to injury color.Painted by sharp objects cut also called injury color, but the degree is slightly lighter.Damage to the color of the utensils on the painting lost its due color and brightness.One of the defects of colored porcelain painting.Refers to the fall of color on the glaze.The painted patterns on the utensils are damaged due to prolonged use and friction, or corroded due to age in the ground (gold color is easier to fall off for this reason). Long-term wiping or brushing will also make the painted patterns fall off.Song Dynasty ding kiln, jianyang kiln gold often color phenomenon.The phenomenon of pastel color is more, especially the pastel of Qing Yongzheng.Traces of these stripped-on porcelain are still discernable, but they require careful observation.One of the defects of glazed porcelain glaze, glaze and color of utensils after friction, showing a very unnatural greasy brightness.Want to know more identification points, click below Li Guogang “ancient porcelain identification series tutorial”, together to improve the eyesight, happy collection.