Antique Porcelain Age Signs

Porcelain age signs give us an opportunity to determine whether a ceramic item is really antique or more recently made. Age characteristics can be fake, but the average age faking can be detected by knowledgeable collectors or dealers.

If a piece of China shows no visible 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.

But, you need to be aware that the age signs of ceramics are different from those of other antiques. You cannot come and decide age because an item looks old or gives the feeling of age.
Sometimes genuine age signs are very subtle, or an item shows some production traces belonging to earlier eras.
See also Faking the Age of Porcelain

Easily recognizable porcelain age characteristics    

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 a very long time.

   Ming bowl with its
   glaze almost gone

Discolored Mingbowl

With shipwreck porcelain that has been in the water for less than 200 years, many items are still in superb condition now and may show little discoloration or bleaching.

On the other hand, shipwreck items 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 get diluted. With blue and white porcelain often a diluted whitish-blue appearance can be the result.

Crackles may be another exception... crackle lines can turn yellowish brown with age even under normal circumstances

Discolored crackles can
be a sign of age

But be careful, crackles can be and are created artificially since ancient times, and they lend themselves for making an item look old. It is necessary to always check carefully whether porcelain age signs are genuine or made to deceive unsuspecting buyers.

In fact the Ge wares of the Song dynasty (960-1279) were made exclusively with crackles as main decoration. Such wares were made throughout the history of Chinese porcelain.

Shown below is the crackled surface of a Ming dynasty jar.    
These are not artificially induced

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 are light brown if enlarged.

Glaze contractions:
Glaze contractions can be a porcelain age sign, but not in the sense of the porcelain having "aged". Instead, they are rather symptoms of kiln conditions at the time of manufacture. Glaze contractions are found in early porcelain, as for example in Ming dynasty porcelain, but also in items made as late as the early 20th century.
They can be considered as "indirect" or "circumstantial" porcelain age signs, an indication of the production environment and methods at the time an item was manufactured.

Think of them as  manufacturing traces pertaining to a period or era when kiln conditions were such that glaze contractions developed on porcelain.
The absence of such contractions when there should be some for the period concerned might mean that an item is not of the period, that means it may have been made later in a modern kiln.

However, please note that many porcelain items of the 18th century do not show glaze contractions. If an item looks as if it were from the 18th century, but has glaze contractions, we need to evaluate whether these could be fake or from the 19th century.


Introduction to Chinese Porcelain

Glaze contractions are small spots where a hole or recess appears on the glaze surface of Chinese porcelain. They have a relatively simple explanation.

One of the main causes is some oily or combustible substance sticking to the clay surface before the glaze was applied. The glaze covers that substance but not the body itself.
With the high firing temperature of the kiln the adhering matter evaporates as it has a low evaporation ot combustion point.

Recesses in the glaze
clearly visible

This leaves a spot without glaze on the porcelain body. The melting glaze will flow into that empty spot sometimes; depending on the glaze thickness of the surrounding area the empty spot may be completely filled or only partially. This may then result in a concave spot (indent) or tiny hole in the glaze.

In some cases the spots are very shallow and are only visible if viewed at 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 of an antique item, better check carefully for rust spots or other age signs. The item may not be that old after all. Always also check also the bottom area and inside in case of of vessels. See firing faults.

Wear of on-glaze decoration:
Gilt and black of "on-glaze" decorations show normally some minimal or more severe 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 also be indicative of the period of manufacture. These can be used in the same way as other porcelain age signs for verification of authenticity and dating.
Keep in mind that some colors were not available until later in the Qing dynasty, or were only used for limited periods, or with specific item types. Certain colors were available for decorating porcelain only after materials or techniques were developed, which made it possible for the colors to remain viewable after firing in the kiln. Thus colors we may know but which could not be fired at certain times may mean that items from that specific period are later fakes.

From the end of the Ming dynasty and beginning of the Qing dynasty (17th century) the kilns were able to control quality better. By the Qianlong period, in the second half of the 18th century, quality was at its peak and many defects had virtually disappeared.
However, after the Qianlong period internal strife and the opium wars, Taiping rebellion, etc. were causes for a decrease in quality. This would have been mainly due to the loss of skilled kiln workers who fled to avoid harm, or who may not have been paid and simply left.

more porcelain age signs ...

Glaze Characteristics of Chinese Porcelain

See Porcelain Age Faking Methods

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Glaze Age Signs - Dead Bubbles

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