ENAMELLING. 



587 



rmel!inr. upon the enamel as it gets drier, and rubbing it in eve- 

 SP ~Y~~*' ry direction till it is compressed as closely as possible. 



The next department of the business is Jfring the 

 enamel, as it is technically called, which consists in 

 melting it till it becomes one uniform mass on the sur- 

 face of the copper. But before we proceed to the de- 

 scription of firing, the apparatus for performing it re- 

 mains to be described. 



The first is a ring used to support the edge of the dial 

 while in the fire, so that the feet may not come in con- 

 tact with any substance, as the motion necessary to be 

 given to the dial would certainly disturb or loosen 

 them. These rings, are made at present of one part 

 pipe maker's clay, and two parts of the real Dutch 

 black lead melting pot, ground to a very fine pow- 

 der, and well tempered with water to a consistence si- 

 milar to potters' clay. A large lump of this mixture is 

 placed upon a square spindle, and set by to dry a lit- 

 tle, when it is placed in a lathe or turn bench, and 

 the rings turned out of the solid mass. The quantity 

 placed upon the spindle may be sufficient to gft two 

 sized rings from the same mass by turning the largest 

 size first. To prevent the adhesion of the enamel to the 

 ring, (we mean that which is laid on the under side of 

 the diall, one part of the ring is made like the frus- 

 trum of a very obtuse angled hollow cone, while the 

 other side forms a plane perpendicular to the sides of 

 the cylindrical parts. The dial being laid in the hol- 

 low side, will just touch it at the part where the cop- 

 per is bare, and thereby prevent the adhesion of the 

 enamel. This part of the ring being well rubbed with 

 fine whitening, will still further prevent such an evil. 

 When the dial is placed on the ring, both are to be set 

 on a planch, which is a flat circular piece of fine stone, 

 about 4th of an inch thick, or, in default of this, it 

 may be made of Sturbridge clay ; and, as it is neces- 

 sary to turn the dial in the fire during the whole time 

 it is melting, that it may be equally heated, the planch 

 with the ring ami dial upon it are set upon a small 

 piece of clay, which should be moulded so as to form 

 a segment of a sphere whose diameter may be about 

 live inches. This being laid on the coals, under the 

 muffle, it will be found, with a little practice, that the 

 planch may be very conveniently turned round on the 

 spherical surface itliout slipping off, while the whole 

 of the pl.ite, by tile change of position, will be equal- 

 ly lii'atcd This last mentioned object is by enamellers 

 called a lurnt r. For a representation of this, and the 

 manner of placing the other articles upon it, see Fig. 1 '2, 

 where all of them are shown in section, the dial in this 

 Figure being a curved one, for a watch without a brass 

 edge. A, is the dial ; BB the ring ; C the planch ; 

 anil D the turner. 



When the furnace is sufficiently heated, lay the en- 

 amelled plates upon the hearth, on a ring of a proper 

 size, and there allow them to remain till the moisture 

 is entirely evaporated. The planch is then to be with- 

 drawn from the fire, where it will have attained a 

 white heat, and the plate and ring set on it as nearly 

 in the centre as possible ; when the whole is to be 

 placed upon the turner, under the muffle, and kept in 

 constant motion, until it assumes one uniform surface. 

 It must then be immediately withdrawn with the tongs, 

 and another treated in the same way, till the whole 

 day's work is fired, which, from the various quali- 

 ties that may be given to the work, although made of 

 the same materials, may vary in number from six to 

 three dozen. 



5 



It rarely happens that any plate will come out of Enamelling 

 the first fire without a number of small black or green "" "Y"" 1 " ' 

 specks, which, perhaps, were in the enamel, and had 

 escaped the notice of the operator. In addition to this 

 imperfection, the union of so many small particles of 

 enamel in one mass throws up to the surface a scummy 

 and mottled appearance, which renders the plate, when 

 cold, very unpleasing. It will be necessary to remove 

 these imperfections by first carefully removing the 

 specks with a square graver, whetted so that the face 

 makes nearly a right angle with the plane of either 

 side, observing to hold the index finger of the left hand 

 immediately under that part of the plate where the speck 

 is situated, so as to counteract the pressure given to 

 the graver, and prevent any strain upon the whole, 

 which might cause the enamel to crack when it again 

 approaches the fire. When all the specks are removed, 

 the centre hole of the copper, if all has been conducted 

 right, will appear to rise above the surface of the ena- 

 mel. This must be very carefully filed down, and the 

 same operation practised at the edge, which will be 

 found to have a similar appearance, and the plate is 

 then ready to undergo a process, technically called using 

 off. This is performed by rubbing the surface of the 

 plate on a grit stone, with fine sand and water, until all 

 the glazed appearance is completely obliterated, and one 

 uniform and equally rough surface is produced. The 

 intention of this part of the process, is to remove the 

 mottled appearance on the surface, and give a more .equal 

 convexity to the plate. It may likwise be observed, 

 that the flux in the enamel being always in the greatest 

 quantity near the surface, gives a semi-transparent ap- 

 pearance to the plate. The using off' removes this im- 

 perfection, and greatly increases the intense whiteness 

 of the ennmel, adding, at the same time, much to its 

 beautiful opacity. After the using oft' is completed, 

 the plates should be brushed with a stiff' haired brush 

 and wet sand, to remove any light stain ; when, being 

 well washed in clean water, they must be dried with a 

 clean napkin, and they are ready to receive the finish- 

 ing fire. 



As the specks that have been picked out generally 

 leave some deep holes in the enamel, they must be fill- 

 ed up with some of the finest enamel, nearly as fine as 

 flour ; and being placed in a proper sized ring, must 

 be set on the iron hearth of the furnace, gradually pla- 

 cing it nearer to the fire, until it attains such a heat as 

 will penult it to be placed in the hottest part of the 

 furnace without danger of cracking, which would be 

 very likely to happen if this gradual annealing was 

 not attended to. The ring and plate may now be lift- 

 ed upon the planch with the tongs, and kept in mo- 

 tion, turning it gently round until it attains a white 

 heat. As soon as this is observed, it must be brought 

 out of the fire, and blown upon with the breath for two 

 or three seconds, and immediately returned into the 

 furnace, where it may Ix; suffered to attain a white 

 heat, which will bring it to a most beautiful gloss, and 

 a degree of whiteness not to be exceeded. The plate 

 must not be permitted to remain one moment longer in 

 the fire after it has arrived at the desired hat, but 

 must be quickly withdrawn from the furnace, and set 

 to cool gradually ; when, if it is found to be free from 

 specks, the operation is finished, and the plate ready to 

 have the figures painted upon it. 



If the enamel should have any specks upon the sur- 

 face, they can only be removed by the graver, and the 

 firing repeated, omitting the using off'in this case. 



