The news and herald. (Winnsboro, S.C.) 1877-1900, 1894-09-06
GLASS WORKING.
eeculiarIties OF the Manufacture by Ona
Who Knows His Business.

Who Knows His Business.
A writer IN the Optician states
that glass is substance which, as
the glass blower says, has will ofits
own. II is very often difficult to tell
how a particular piece is going to act
under certain conditions. even after
having tested other pieces Of the
same batch" When subjected to
the heat one Of tube Will some
times respond differently from the
other end. This is in measure due
to unequal chilling, occasioned pos.
sibly by sudden draught Of air
while it IS in process Of manufacture.
No piece Of glass is absolutely reli-
able. Its working is, therefore, at
certain stages, most uncertain, and
one person may have entirely differ
ent experiences from another 1t IS
cnameIeonlike, and every process
succeeds better with those who seem
TO have a knack which is generally
OBTAINED by i ng practice.
The cutting Of glass heads the list
of the uncertain processes, for 1t has
no definite cleavage, and its separa-
tion is modified by the surrounding
temperature is on fiat glass in a
stra ght line. Here all that is neces-
sary is a deep and regular scratch
with a glazler's diamond. firm and
speedy bend away from the main
p!ece and the parts crack along the
desired line. These glaciers dia-
mouds may be purchased and gener-
ally prove satisfactory, but it is more
economical to purchase from some
diamond cutter small splinter, and
insert this into a piece Of brass rcd
having q small hole drilled into one
end. The splinter should NV be
cemented with marine glue and the
brass rod tiled Little upln the side
nearest tht ru er, to Obtain, attei
trial, the best cutting angle for the
diamond. Another instrument for
cutting glass less expensive than the
4 a:ncnd is the glass-blower's knife,
which is thin piece of steel tenn
pered glass hard BY heating it cherry
red and then plunging it into ice;
cold wa er or mercury. The edge
should be sharpened by rubbing it
u on an old, rough emery grindstone
until fine Sawlike notches appear. 1t
is then ready for use and should, il
much used, be sharpened repeatedly.
TO cut tubes, carefully scratch at
right angles TO the axis deep notch,
either with the diamond, triangu7
lar tile. or a 6 asS-bloWer's knife;
Heat a piece of glass rod until a
small gIobule appears on the end, and
press this upon the scratch. Tho
glass will thus be heated more at this
loint than at any other; an unequal
| expansion takes place, the scratch
giving direction to the line d frac7
tu.e, aud the tube cracks evenly il
its thickness is uniform. In the case
! OF va liable thickness uneven edges
! result, and these must be fled down
to avoid sharp cutting splinters;;
Many recipes and directions have
leen given for cutting bottles. Wet
ting an asbestos string with turpen,
tine and setting it on fire produces
considerable heat in the glass i'm
mediately underneath it. RyQuicklS
removing the string and plunging the
! bottle into cool water the unequal
strain takes place and the part;
separate. It is this locating Of the
heat that causes the glass to crack a.
we wish it. The easiest method, il
| the means be at hand, is to employ
platinum wire which should be heated
white hot by The passage Of heavy
electric current. By wrapping the
w,re round a heavy bottle or jar and
allowing the current to pass for ten
or tfteen seconds stoutest walled
! yeSse may be easily separated il
/ touched on the heated line with d
Goth dipped in water.