ENAMELS 



275 



831 



a Planche. 



b Bed of whiting. 



clay, supported on a bed of whiting, thoroughly dried in the furnace, the exact shape 

 of the plate as originally made, which must be used in all subsequent firings. After 

 the whiting is formed in the shape of the plate it should be notched with a flat knife 

 diagonally across, as in the accompanying diagram, 

 (fig. 831). The use of this is to produce an effect of 

 diagonal bracing while the plate cools, and experience 

 has shown that it tends considerably to keep the plate 

 in its original shape. When the plate is small (up to 

 throe inches in length) it maybe annealed for passing 

 into the hot muffle as follows: The planche bearing 

 the plate may be placed on another planche heated 

 in the muffle and placed in the front of the muffle for 

 a few minutes, until the steam of the plate or the oil of 

 the picture shall have evaporated ; it may then be put 

 in the mouth of the muffle, and gradually inserted to the 

 hottest part. After firing it should be placed on an- 

 other hot planche, and allowed to cool gradually. Large pictures require a different 

 arrangement of the furnace. Over the muffle there should bo a fixed iron annealing 

 box, with an iron shelf and door. The bottom should be of cast iron about one inch 

 thick. This should be so arranged that when the muffle attains a white heat the bottom 

 of the annealing box should be of a brightish red at the back, and a dull blood-red in 

 front. Large pictures should be placed on the bottom of the box before the furnace 

 is lit, and the larger the size of the picture the slower should the furnace be brought 

 to its full heat, so as to allow five or six hours for the largest size, and two or three 

 for smaller plates. When fired the picture should be returned to the shelf of the 

 annealing box, and left there till quite cold, for which purpose large plates require at 

 least twelve hours. The colours used are mostly the same as those prepared for 

 jewellers and glass painters. 



Enamelling at the Lamp. The art of the lamp enameller is one of the most agree- 

 able and amusing that we know. There is hardly a subject in enamel which may 

 not be executed by the lamp-flame in very little time, and more or less perfectly, 

 according to the dexterity of the artist, and his acquaintance with the principles of 

 modelling. 



In working at the lamp, tubes and rods of glass and enamel must be provided, of 

 all sizes and colours. 



The enamelling table is represented in fig. 832, round which several workmen, with 

 their lamps, may be placed, while the large double bellows D below is set a-blowing 

 by a treadle moved with the foot. The flame of the lamp, when thus impelled by a 

 powerful jet of air, acquires surprising intensity. The bent nozzles or tubes A, A, A, A, 

 are made of glass, and are drawn to points modified to the purpose of the enameller. 



832 



833 



Fig. 833 shows, in perspective, the lamp A of the enameller standing in its cistern 

 B ; the blowpipe c is seen projecting its flame obliquely upwards. The blowpipe is 

 adjustable in an elastic cork D, which fills up exactly the hole of the table into which 

 it enters. When only one person is to work at a table provided with several lamps, 

 ho sits down at the same side with the pedal of the bellows ; he takes out the other 

 blowpipes, and plugs the holes in the table with solid corks. 



The lamp is made of copper or tin plate, the wick of cotton threads, and either 

 tallow or oil may bo used. Between the lamp and the workman, a small board or 

 sheet of white iron, B, called the screen, is interposed to protect his eyes from the 

 glare of light. The screen is fastened to the table by a wooden stem, and it throws 

 its shadow on his face. 



T 2 



