Glass Working Exercises 



rot 



the bulb), and finally to blow out while rotating the tubes, and 

 pressing them together slightly. 



Blowing and rotating simultaneously is arranged by wetting the 

 tube so that it slips round in the lips, which should never grip the 

 tube tightly. 



Although many failures may be expected before success is 

 finally attained, always and from the first a strong bulb should be 

 produced. Weak and excessively thin bulbs denote failure to 

 grasp the preceding method, and no subsequent exercise should 

 be attempted until this fault is overcome. At the same time, it is 

 not recommended that a student remain at this exercise until 

 absolute certainty of obtaining a spherical bulb be attained. 

 Practice at subsequent work will materially enhance his skill in 

 dealing with hot glass, and consequently his prospect of success with 

 this somewhat difficult exercise. 



EXERCISE 6. To blow a bulb at the end of a tube. 



This exercise should be continued until absolute certainty is 

 acquired. Subsequent exercises should not be attempted until this 

 is the case, as upon its accurate and reliable performance many of 

 them depend. 



First close the tube as in Exercise 2, and produce the rounded 



FIG. 90. Stages in the blowing 01 a bulb at the end of a piece of tubing. 



end shown there. Holding the tube horizontally, heat it for about 

 i cm. at the end, transfer it horizontally to the mouth when fairly 

 soft, and blow gently. The glass, on softening, will show a tendency 

 to bend over, and this must be at once counteracted by a twist 



