Glass Working Exercises &7 



It will be noticed that these are mental rather than physical 

 attributes, consequently a glass-blower will become successful 

 when these have been so thoroughly absorbed and incorporated 

 into his personality as to become subconscious. 



III. EXERCISES IN GLASS BENDING. 



For this purpose a "batswing" burner should be used, 

 though it should never be turned full on save under very 

 exceptional circumstances. The flame consists of two parts 

 a cool " blue " or transparent centre portion, and a hot luminous 

 fringe. This latter is the part to be used. 



EXERCISE i. Take a piece of 4-mm. bore tube, about 15 cms. 

 long, hold it lightly between the thumb and forefinger of the right 

 hand, in the upper portion of a flame such as that shown in Fig. 

 75 (2) ; holding with the left hand is not necessary, though it may be 

 used as a guide. Turn the tube 

 slowly and regularly upon its 

 axis, taking care to give a com- 

 plete revolution before turning 

 back. The revolution may be 

 at the rate of once in about four 

 seconds. A higher speed is FIG. 75. Batswing flame : (i) turned 

 more difficult to control, and 0^11^(2) turned down /or glass 



has no advantage in increased 



evenness of heating. If the tube is being correctly held, it will 

 be covered with an even film of carbon at the end of the first 

 complete revolution. Should it be otherwise, the position must 

 be altered till the carbon deposits evenly over the whole of the 

 surface to be heated. There is a tendency to hold the tube too 

 low in the flame, and this will be shown at once by an uncovered 

 space upon the tube. 



Proceed with this slow rotation until the unsupported end of 

 the tube shows a tendency to fall ; then cease rotating the tube, 

 and simply invert it, allowing the tube to straighten itself out. 

 Then remove from the flame immediately, and allow the end to 

 bend down at its own rate until the desired angle has been 

 reached, when the. tube may be held by both hands in that position, 

 until sufficiently cool to be put down without j risk of further 



