Porcelain age signs give us the opportunity to determine whether a ceramic item is really antique or recently made. Age characteristics can be faked, but with the average age faking can be detected by knowledgable collectors or specialists.
If a piece of China shows no visible porcelain age signs at all, we consider it as recently made. On the other hand, if there are too many age signs present it is necessary to carefully check in detail to make sure the item is not a fake.
Faking the age of porcelain
Discoloration and Glaze Deterioriation:
Glaze and decoration do not get discolored under normal circumstances with porcelain, even over extended periods of time.
An exception are items that have been in the soil or sea for long periods of time.
Ming bowl with glaze almost gone
For example, with shipwreck porcelain that has been in the water for less than 200 years, many items are still in superb condition now and may not show any relevant discoloration.
Those that have been in the sea for several hundred years often have little or no glaze left. Without its protective cover gone the decoration color of porcelain can change. With blue and white porcelain often a diluting of the blue color and overall white appearance is the result.
Crackles Crackles may be another exception... The crackle lines may change to yellowish brown with age.
Discolored crackles can be a sign of age
But careful, crackles can be created artificially and lend themselves to make an item look old. It is necessary to alway check carefully whether the aging is genuine or made to deceive unsuspecting buyers.
Rust spots:
Iron residue contained in the clay moves slowly to the surface of the ceramic body over a long period of time, forming small rust spots. On rare occasions these may be larger, but mostly they appear as tiny spots.
Rust spots may look black to the eye if small, but brownish if larger.
Glaze contractions: Glaze contractions can be a sign of age, but they are not always. They are the result of kiln conditions more often found in ancient kilns. However some 20th century porcelains can show these too, thus it depends on the circumstances whether they can be considered as porcelain age signs. It might be preferable to think of them as a sign of ancient kiln conditions than porcelain age signs.
Glaze contractions are small spots where a hole or recess appears on the surface of Chinese porcelain. The glaze either does not cover the clay body at all or shows a shallow recess (indent). They mainly appear on antique Chinese ceramics exceeding a certain age, and may be more frequent on porcelain of certain periods. But, some newer kilns may also show contractions. To complicate things, the wares of some kilns or periods (e.g. Qianlong period) may have little or no contractions because of improved control over the work environment. The glaze is clearly concave (looks indented) at these spots.
One of the main causes is some oily or fatty substance sticking to the clay surface before the glaze was applied. The glaze covers that substance but not the body itself. In the high temperature of the kiln the adhering material evaporates as it has a low point of evaporation or combustion. This leaves a spot without glaze on the body. The melting glaze will flow into that empty spot sometimes; depending on the glaze thickness of the surrounding area the empty spot may not or only partially be filled. This results in a concave spot or miniscule hole in the glaze.
In some cases the spots are very shallow and only visible if viewed from an angle, depending on the light conditions. Deeper contraction spots may be brown or black because of sediments or residual dirt inside.
Chinese porcelain exceeding a certain age normally shows some glaze contractions. If there are none at all on the whole body or bottom, better check carefully for rust spots or other age signs. The item may not be that old if nothing at all is found. Always also check also the bottom and inside of vessels. See
firing faults.
Wear of overglaze decoration:
Gilt and other "on-glaze" decoration normally shows wear if a porcelain item has been in actual use rather than on display only.
Presence or absence of certain colors:
The presence or absence of certain colors in the decoration can be indicative of the period of manufacture.
Keep in mind that some colors were not available until later in the Qing dynasty. Certain colors were available for decorating porcelain only after materials or techniques were developed, later on in the Qing dynasty, which made it possible for the colors to remain visible after firing in the kiln.
Crackled surface of Ming dynasty jar
