age of resting the arms against the table is more
important.
Sec. 19. Special Operations.
The preliminary to most operations before the blow-pipe, is to draw
down a tube and pull it out to a fine point. This is also the
operation on which a beginner should exercise himself in the first
instance. I will suppose that it is desired to draw out a tube about
one-quarter of an inch in diameter, with the object of closing it,
either permanently or temporarily, and leaving a handle for future
operations in the shape of the point, thin enough to cool quickly and
so not delay further work.
For this simple operation most of the glass-blower's skill is
required. The tube must be grasped between the first finger and thumb
of both hands, and held so that the part to be operated on lies evenly
between the two hands. The distance between the operator's thumbs may
conveniently vary from 2.5 to 4 inches. Releasing the grip of the
left hand, let the operator assure himself of his ability to easily
rotate the tube about its axis--by the right thumb and finger--he
will incidentally observe by the "feel" whether the tube is straight
or not.
A good deal of progress can be made from this point before the tube is
heated at all. The operator can acquire a habit of instinctively
rotating the tube by both hands, however the tube itself be moved
about in space, or however it be pushed or pulled. The habit of
constant and instinctive rotation is literally about one-third of the
whole art of glassblowing. It is unlikely, however, that the beginner
will discover that he has not got this habit, until a few failures
draw his attention to it.
The glass tube being held in position lightly yet firmly, and the
operator being sure that he feels comfortable and at his ease, and
that the blow-pipe flame (a single flame in this instance) is well
under control, the preliminary heating may be commenced. With a tube
of the dimensions given this is a very simple affair. Turn the air
partly off, or blow gently, to get a partly luminous gas flame; hold
the tube about an inch from the end of this flame, and turn it round
and round till it commences to soften.
In the case of soda glass it is usual to employ the gas flame only,
but I find that it is better in most cases to use the hot air of a
gently-blown flame, rather than have the disadvantage of the soot
deposited in the alternative operation. When the glass begins to
soften, or even befor
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