CHIPPING, a phrase used by the potters and chinamen to express that common accident both of our own stone and earthen ware, and of the porcelain of China, which consists in the flying off of small pieces, or breaking at the edges. Our earthen wares are particularly subject to this, and are always spoiled by it before any other flaw appears in them. Our stone wares escape it better; but not so well as the porcelain of China, which is less subject to this species of injury than any other manufacture of the kind in the world. The method by which the Chinese defend their ware from this accident is this: They carefully burn some small bamboo canes to a sort of charcoal, which is very light and very black; this they reduce to a fine powder, and then mix it into a thin paste, with some of the varnish which they use for their ware; they then take the vessels, when dried, and not yet baked, to the wheel, and turning them softly round, cover the whole circumference with a thin coating, by means of a pencil dipped in this paste; after which the vessel is again dried, and the border made with this paste appears of a pale grayish colour when it is thoroughly dry. They work on it afterwards in the common way, covering both this edge and the rest of the vessel with
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Chirograph.
the common varnish. When the whole is baked, the colour given by the ashes disappears, and the edges are as white as any other part; only when the baking has not been sufficient, or the edges have not been covered with the second varnishing, we sometimes find a dusky edge, as in some of the ordinary thick tea-cups. It may be a great advantage to our English manufacturers to attempt something of this kind. The willow is known to make a very light and black charcoal; but the elder, though seldom used, greatly exceeds it. The young green shoots of this shrub, which are almost all pith, make the lightest and the blackest of all charcoal, which readily mixes with any liquid, and might be easily used in the same way as the Chinese use the charcoal of the bamboo cane, which is a light hollow vegetable, more resembling the elder shoots than any other English plant. It is no wonder that the fixed salt and oil contained in this charcoal should be able to penetrate the yet raw edges of the ware, and to give them in the subsequent baking a somewhat different degree of vitrification from the other parts of the vessel; which, however, if given to the whole, might take off from the true semivitrified state of that ware, whereas at the edges it is not to be regarded, and only serves to defend them from common accidents, and keep them entire. The Chinese use two precautions in this application; the first in the preparation, and the second in the laying it on. They prepare the bamboo canes for burning into charcoal by peeling off the rind. This might easily be done with our elder shoots, which are so succulent that the bark strips off with a touch. The Chinese say that if this were not done with their bamboo, the edges touched with the paste would burst in the baking, which does not indeed seem very probable; but the charcoal will certainly be lighter when made from the peeled sticks, and this is a known advantage. The other precaution is never to touch the vessel with hands that have any greasy or fatty substance about them; for if this be done they always find the vessel crack in that place.