Enamel

“ Then when you want to apply your enamels, having put a morsel of each colour on your palette (the finger palette I described to you above fixed on to the stem of your leaden pear) you mix with every bit of enamel you lay on your work, a tiny drop of this quince-seed-water, the effect of which is to produce a kind of gum which holds the enamels together so that they don’t fall, & no other gum has a like effect. ”

“ It is now attentively watched until the enamel shines all over, when it is withdrawn from the furnace. The firing of enamel, unlike that of glass or pottery, takes only a few minutes, and in nearly all processes no annealing is required.
The following are the different modes of enamelling: champlevé, cloisonné, basse-taille, plique-à-jour, painted enamel, encrusted, and miniature-painted. These processes were known at successive periods of ancient art in the order in which they are named. To-day they are known in their entirety. Each has been largely developed and improved. ”

“ We will confine our attention to what is known as hard enamel in contradistinction to japans, lacquers, and enamel paints, which are often called soft enamels. Hard enamels are compounds of glass with different metallic oxides which produce the different colors. ”

“ Composition of the teeth? Enamel of the teeth? Interior of teeth?
6. The teeth are composed of a bone-like material, and are held in place by roots running deeply into the jaw. The exposed portion, or "crown," is protected by a thin layer of enamel (Fig. 17, a) , the hardest substance in the body, and, like flint, is capable of striking fire with steel. In the interior of each tooth is a cavity, containing blood-vessels and a nerve, which enter it through a minute opening at the point of the root (Fig. 19) . ”

“ The method of laying a white upon the enamel ground is a matter of individual taste, so far as the medium is concerned. By some, pure distilled water is preferred to any other liquid for mixing the enamel. ”

“ Teeth are made up of three different substances, which are known as enamel, dentine and cement.
The enamel is a very hard substance, the hardest in the body, and may be compared to quartz. The enamel covers the entire tooth down as far as the gums. ”

“ This author believes the enamel of the teeth to be of the nature of stone, and the ivory of the nature of bone. The dental roots, which, he says, are precisely of a bony nature, are covered over with a periosteum, which is in close relation with the gums and with the periosteum of the jaw bone. Clopton Havers held that the dental follicle no longer furnishes any nourishment to the enamel from the moment that this has reached its perfect formation. ”

“ On the under surface of this oblique tooth band (still taking the lower jaw) , and close to its edge, appear ten thickenings, below each of which the mesoderm rises up into a “ dental papilla, " and so moulds the thickening into a cap for itself-the “ enamel organ.” ”

“ There are many of these so-called enamels to-day, which are much easier of accomplishment than the true enamel, but they possess none of the beautiful quality of the latter. It is most apparent when parts of a work are true enamels and parts are done in the manner described above. ”

“ The scalpriform incisors of the rodents, already alluded to, have the enamel band on the front face of the tooth; the softer dentine behind wears away more rapidly, keeping the cutting surface bevelled, like the edge of a chisel, while the hard enamel forms the sharp edge. In some instances the enamel is absent altogether and the teeth are composed entirely of dentine, as in the elephant tusk. ”

“ To make enamel. Enamel is thus made: take lead, and melt it, continually taking off the pellicle which floats on the surface, until the whole of the lead is wasted away; of which take one part, and of the powder here- after mentioned, as much; and this is the said powder: take small white pebbles which are found in streams, and pound them into most subtle powder; and if you wish to have yellow enamel, add oil of filberts and stir with a hazle rod; for green, add filings of copper, or verdigris ”

“ Whenever this enamel is worn through by too coarse a powder, or too frequently cleaning the teeth, or eaten through by a scorbutic humor in the gums, the tooth cannot remain long sound, any more than a filbert-kernel can, when it has been penetrated by a worm. ”

“ Then a deep groove is made in the middle of the upper teeth, crossing them all, and itself cutting through at least one-fourth of the whole thickness of the teeth, so that the enamel is cut quite through, a fact which we Europeans, who are taught by our dentifricators that any damage done to the enamel is mortal to the tooth, find it difficult to believe. ”

“ These chunks of enamel may be readily broken up by a hammer, and if they are first wrapped in a piece of cloth the small particles will not fly about and get into one’s eye, and no enamel will be lost. ”

“ The tooth pushes thru the gum; and as it goes by, the cells at the sides of the pocket and on top plaster it with a coating of enamel. Therefore, as most of us find out to our cost, this enamel once destroyed, can never grow again. Once clear of the pocket where it was formed, it has to last us the rest of our lives; and little boys and girls who don’t keep their teeth clean when they are young, have to put up with something not nearly so good when they are grown up. ”

“ If the silver is not “fire-stained,” red enamel will often become maroon when fired, and fondant and other delicate colors will become streaked or spotted. If the fire-staining and dipping have not been carefully done, the enamel is likely to chip out, have pit-holes in it, or contain black blotches.
As the acid fumes eat the flesh quite rapidly, it is advisable to wear rubber gloves when dipping the metals.
14 CHAPTER III
CHARGING Enamel is “charged,” or put on the metal, in the form of a watery mud, by means of a small spatula. ”

“ The ivory, however, is always nearly on a level with the enamel, notwithstanding the greater attrition which the substance forming the principal portion of the table of the tooth must necessarily endure. A sufficient indentation of the ivory, nevertheless, can be observed, to render prominent the ridge of enamel, and to indicate that the last-named material is endowed with the greatest power of resistance. ”

“ Disposition to caries shows itself even in the developing tooth in the composition of its enamel, which is undulating, whereas teeth with quite smooth enamel have much greater power of resistance. The enamel appears to be the only tissue in the body which is subject to no metabolism, and which remains quite unchanged. Every alteration in it which is caused by external influences, and every defect of the enamel, remains during the whole of life, and can never be repaired. Dentine also shows differences in structure as regards its disposition to caries. ”

“ The tubules of the dentine lodge excessively fine fibrillæ of the nerve and that is why the cutting into a live tooth is so painful an operation. (2) The enamel, which is the hardest of all animal tissues, has a polished and shining appearance and is arranged in a mosaic of microscopic prisms, closely packed together, which in most mammals are solid, but in the marsupials, with some exceptions, are tubular. ”

“ Each tooth has a biting part or crown covered by enamel, a neck Where the gum surrounds it, and one or more roots or fangs fitting into sockets (alveoli) in the jaw bone. For surgery of the teeth see Dentistry.
There are thirty-two permanent teeth in man, sixteen in the upper and sixteen in the lower jaw; they are also arranged in symmetrical sets of eight teeth on each side. ”

“ If for some reason a piece has been enameled wrong, so that it is desirable to take the enamel off the metal, this can best be done by leaving the piece for a few hours in a solution of hydrofluoric acid which will eat the enamel, so that it can easily be brushed off the metal, leaving it bright. ”

“ Of the many decorative arts, enamelling is one of the most beautiful, having a singular charm of limpid or opalescent colour of great purity, richness and durability, and being capable of a most refined and varied treatment for the enrichment of metals.
Enamel is a vitreous or glass compound, translucent, semi-translucent or opaque, owing its colouring properties to mineral oxides, or sulphides, a fine opaque white being produced by oxide of tin. These enamels require different degrees of heat in order to fuse them and to cause their adhesion to the metal. ”

“ The enamel of the teeth is formed once for all during childhood. The substance of the teeth is mineral, chiefly lime. It will therefore be appreciated that the child needs abundance of mineral in order that he may have sound tooth material. This he can get only from mineral in his food (see page 169) , or, before his birth, from his mother’s diet. Good circulation in the jaws is also essential for normal development both for teeth and jaws, therefore the importance of some hard food every day after ten months. ”

“ But it is necessary to buy good quality articles, as in the cheaper classes the enamel is often thin, inferior and contaminated with arsenic. Inferior enamel is apt to chip, and this is dangerous, as the particles are as sharp as glass and capable of causing serious digestive troubles. ”

“ Enamel may be applied to metal objects and add a great deal to their value and attractiveness if used sparingly. The enamels most used are transparent and opaque; the transparent reflects the color of the metal adding a great deal of life to the work, the opaque gives color on the surface only. ”

“ They act in the following manner:—The spirit, being very liquid or thin in its nature, wets the enamel and passes by it when it rises in the stalk, so that the elevation of temperature does not affect its position, but when the spirit sinks down it drags the enamel with it, thus registering the lowest temperature, so that the distance the enamel is found down the stalk indicates how low the spirit may have descended in any particular time, say a night. ”

“ Plique-à-jour enamel is similar to cloisonné except that the wires are soldered to each other without any background, thus forming a sort of filigree, the spaces within which, when filled with enamel, somewhat resemble a stained-glass window.
In enamel painting a picture is painted on the enamel. Usually white opaque enamel is used for the background, and the painting is executed with finely ground enamel or china paints, after which it is covered with a layer of transparent enamel which serves as a protection for the painting. ”

“ As the tooth wears, the surface, besides the external enamel layer as in an ordinary simple tooth, shows in addition a second inner ring of the same hard substance surrounding the pit, which adds greatly to the efficiency of the tooth as an organ for biting tough, fibrous substances. ”

“ THE CARE OF THE TEETH.
Decay of the teeth, or caries, commences externally, appearing upon the
enamel or bony structure of the teeth. Usually it is the result of
chemical action produced by decomposition of food. Acids found in some
fruits will cause decay if allowed to remain in contact with the teeth. ”

“ The enamel is restricted to the front of the incisor, so that in gnawing the softer dentine is worn away at the tip faster than the enamel, thus keeping the tooth sharp. There are no canine teeth. Rodents are mostly herbivorous in diet, are usually small, and have clawed digits. ”

“ They are formed in front of hard, orange-colored enamel, while the back of the tooth is formed of a softer substance, more easily worn down, so that a sharp, chisel-like edge is always preserved; the bulbs being also persistent, so that the teeth are continually growing as they are worn away. ”

“ Haviland & Co., who may be taken as a standard, classify their faïences into six groups—viz. cream faïences, which are thus named from their color, and which are decorated with paintings under the enamel or with translucid enamels; enamelled paintings, possessing all the tone, richness and variety of oil-paintings; grand-fire fresco paintings, or exact representations of wall frescoes, and especially adapted for panels or architectural ornaments; gilt enamels, reproducing Chinese lac-paintings or vases of precious stones; Limoges enamels, very similar to the ancient enamels of Léonard Limousin ”

“ When several flat enamels are to be applied to one article, the greatest of care should be taken to see that one color does not run over the other. They should be separated by heavy lines—and each one dried. ”

“ Now place a quantity of black or brown dry enamel paint on the plate and gently scatter this powder over it by means of a soft, clean, dry brush, which should be kept for this 64purpose only. Then brush the enamel powder back into its bottle. It is very essential that no dust shall get into it. After five or ten minutes repeat the powdering and so on two or three times until the picture is clearly developed. ”

“ Moreover, while the earlier types have a comparatively full series of teeth, all of which are rooted and invested with enamel, in the later forms the incisors are lost, the cheek-teeth never develop roots but grow continuously throughout life. ”

“ As the tooth wears in its work, the enamel comes to project above the surface of the tooth, and a characteristic pattern is thus developed on the surface of the molars of each species of living elephant. ”

“ They crack or wear away the enamel of the teeth, leave the nerve exposed, and cause the teeth to decay. If you are wise, dear reader, you will never use a dentrifice, unless you know what it is made of. ”

“ On the slightest appearance of decay or tendency to accumulate tartar, go at once to the dentist. If a dark spot appearing under the enamel is neglected, it will eat in until the tooth is eventually destroyed. ”