The Wichita daily eagle. [volume] (Wichita, Kan.) 1890-1906, 1894-08-11
GLASS WORKING.
The Delicate Process Is Attended With
Much Uncertainty.

The Delicate Process Is Attended With
Much Uncertainty.
A writer in the Optician states that
glass is substance which, as the glaso"
blower says, has a will of its own &c
is very often difficult to tell how par
ticular piece is going to act under GER
tain conditions, even after having
tested other pieces of the same batch"
When subjected to the heat one end Of
a tube will sometimes respond diff
ferently from the other end. This IS
IN measure due to unequal chilling,
occasioned possibly by sudden
draught of air while it is in process
of manufacture. No piece Of glass is
absolutely reliable. Its working Is,
therefore, at certain stages, most IN
certain, and one person may have en-
tirely different experiences from
another. 1t is chameleonlilze, and
every process succeeds better with
those who seem TO have a knack which
is generally obtained by long practice.
The cutting of glass heads the list Of
tho uncertain processes, for it has no
definite cleavage, and its separation is
modified by the surrounding Temporal
ture. The simplest separation is on
fiat glass in straight line. Here all
that Is necessarssis a deep and regular
scratch with q glaciers diamond, a
firm and speedy bend away from the
main piece, and the parts crack along
the desired line. These GLACIERS dia-
rnonds may be purchased and general
w 81 h,,% ;e
economical to purchase from some dia-
mond cutter small splinter, and in
sert this into q piece of brass rod hav-
ing small hole drilled into one end.
The splinter should now be cementod
with marine glue and the brass rod
filed little upon the side nearest the
ruler, to obtain, after trial, the best
cutting angle for the diamond. Another
instrument for cutting glass less ex-
pensive than the diamond is the glass
blowers knife, which is piece OF thin
steel tempered glass hard by heating
it cherry red and then plunging it into
ice-cold water or mercury. The edge
should be sharpened by rubbing it upon
an old, rough emery grindstone until
fine saw-ille nOtches appear. 1t is
then ready for use and should, if much
used, be sharpened repeatedly.
To cut tubes, carefully scratch at
right angles to the axis a deep notch,
either with the diamond, triangular
file or a glass blowers knife. Heat a
piece of glass rod until a small globule
appears on the end and press this upon
the scratch The glass will thus be heat
ed more at this point than at any other;
an unequal expansion takes place, the
scratch giving direction to the line of
fracture, and the tube cracks evenly if
Its thickness is uniform. In the case
of variable thickness uneven edges re-
suit, and these must be fled down to
avoid sharp, cutting splinters- Many
recipes and directions have been given
for cutting bottles. Wetting an asbes-
tos string with turpentine and setting
it on fire produces considera BILE heat in
the glass Immediately underneath it.
By quickly removing the string and
plunging the bottle into cool water the
unequal strain takes place and the
parts separate. 1t Is this locating Of
the heat that causes the glass to crack
as we wish IL. The easiest method, IL
the means be at hand, is to employ a
platinum wire, which should be heated
white hot by the passage of heavy
electric current. By wrapping tire
wire round heavy bottle or jar and
allowing the current to pass for ten or
fifteen seconds the stoutest walled YES
sci may be easily separated if touched
on the heated line with cloth dipped
So water.