A traditionally derogative name referring to Chinese export porcelain that has got its original underglaze blue and white decoration added onto in Europe with a later colored enamel decoration. The secondary decoration were sometimes limited to only a new or additional borders, sometimes rough foliage, figures, animals, birds or full landscapes or sceneries, sometimes adding to the old decoration, sometimes randomly filling all available space and sometimes just disregarding the old underglaze blue and white decoration as if it wasn't there.
Pieces with the least merits seem to have been produced in London during the second quarter of the nineteenth century when apparently a great deal of indifferent and un-sellable Chinese blue and white 18th century left over stock were embellished with anything that was colorful.
The practice seems to have originated in Holland but spread over Europe with the availability of items to decorate. This kind of work was extensively done both in Holland and in England during the 18th and early 19th century. The English establishments that offered this service were known as China burners and the enameling was referred to as that the colors was "burnt in and impossible to remove". Some of these "China burners" also seemed to have offered porcelain repairs where broken pieces was ceramically mended in a re-glazing process.
Another praxis that needs to be considered in this, was a related process where damaged or second rate porcelain was improved or mended by hiding the flaws under newly added decorative elements such as random enameled flowers or insects. This could indeed be a literally correct use of the word clobbering as compared to what was done to broken shoes.
The word clobbering seems to stem from the common Irish word clábar meaning "filth, dirt, mire, mud" as listed in A Dictionary of Anglo-Irish Words, together with the Anglicized versions clabber, clauber.
By the end of the 19th century clobber was found in the English language (Oxford English Dictionary) together with clabber, while referring to "a paste used by the shoemakers to patch holes".
Nowadays the word clobber is mostly used as a noun referring to (dirty or worn) clothes and belongings of little merit, and as a verb, to beat up.
When referring to porcelain the word clobbered is traditionally used as a verb i.e. this piece has been clobb'd or this piece is clobb'd.
With increasing interest and knowledge among collectors and scholars it is now increasingly possible to distinguish between many types and different sources of European decorations added to oriental porcelain, and in all cases where a closer desription is possible I feel that this should be attempted.
Language reference: Dymphna Lonergan; Irish Words in Australian English, Ozwords, May 2003