22. (a) What is retort cement?
(b) How does it differ from ordinary clay?
(c) For what purpose is it used in aluminum welding?
23. (a) When performing an aluminum weld by the puddle system, is the welder dependent upon the flame, the “filler-rod” or the puddle stick, for the fusion of the metal?
(b) Give explanations.
24. (a) What method of welding is used when executing a vertical weld on aluminum?
(b) Why isn’t the other method used?
(c) Is the vertical welding of aluminum to be avoided?
25. (a) Can aluminum welds be made overhead?
(b) Explain why.