Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1913-03-26


| mitted To partially dry The next step is
one of the most interesting to the obser-
yer. tor it is here that the blanks are
| given the form they retain through sue
! ceedIng processes. Standing at a
! light lathe of much the same type as
J is employed by Woodworkers. deft-
| fingered workman takes one of the
! partly dried blanks, inserts it in The
porcelain. determining the dimensions
lathe, grasps a soft file ground Ia
urements obtained here are not those
that prevail when the blank has beea
put through tile kiln. There comes a
shrinkage of perhaps - per cent in
length and II per cent in diameter, or
the proportions may be reversed, ac-
crding as the chemist regulates his
mixture. but the dimensions are rcla-
lively the same, hence great care is
necessary.
The room where most of the turning
is done is never sraced by the presence
of an outsider, for the appliances used
here and the processes brought into play
are not for the delectation of prying
eyes.
In the dipping-room the blanks are sub
jected to plunge in a thin solution
known as glaze, the absorbent nature Of
the clay causing this to be taken up al
most on the instant. Herein lies a no.
table difference between porcelain and
other ceramic wares. the body and glaze
being fired together, while with other
varieties the clay is first fired, after
which the glaze is applied, and the whole
is again fired at much lower heat
r. arl. tln
dipping consists merely of inserting
bit of wire in either end and submerg-
ing the blank, the wires being with
drawn after all danger of the glaze en-
tering the aperture running lengthwise
through the blank is passed. With Il
visible plug, where there is transverse
aperture, an air-eontrolled tube is en-
ployed, a slight pressure by the operator
causing the tube to expand and cut off
if1eress, while release of the pressure
enables it to be Withdrawn without in-
turing the blank or its coating. The lat
ter is a chalk-like covering that can be
removed with slight pressure of the
fngernaH. but when properly baked it
could not be separated from the blank
in any manner.
Into clay crucibles. known TO the trade
rs "seggars," go the dipped blanks.
Each must stand upright in such man
ner as not to touch any of the rest, Tor
obvious reasons. When placed in the
kiln, these blanks possess peculiar proper
ties. For example, if an undipped blank
was placed in Il group of glaze-treated
ones, when the seggar was taken from
the furnace it would be found that the
,,n1 ataa nnSG4eGpd u fbOrOit4h rlIt-
ing of glaze, while those that had been
subjected to a preliminary bath would
have suffered Il material loss on the sides
exposed to the Gntreated one The bases
of the blanks are inserted in mixture
less susceptible to heat. so that when
the firing is over they can be readily re-
moved. one hundred and eighty blanks
to a seggar is the allotment. and when
You understand that a kiln will hold
lt0a0 blanks, it becomes apparent that
preparing a charge is no small task.
Strips of clay are placed between he
seggars at the edges. and when the kiln
is filled the opening or door is bricked
up, thoroughly luted with fire clay, and
bands are run about the furnace. being
brought up tight with turnbuckles, 50
that there can be no possible chance for
expansion that will admit air.
Firing is in reality one of the most i'm
portant stages, for with the best of
planning there are bound to be varia-
tions, and the slightest slip might mean
the loss of an entire charge. The tenn
perature in these kilns rises somewhat
above summer heat 2600 degrees being
registered during the baking process,
which varies in length. A couple of days
after the fires have been eXtinguished
the kiln cools sufficiently SO that the
seggars may be removed. this gradual
cooling assisting in the annealing pro-
cess.
Putting a name on the porcelain seems
simple enough procedure. However, 1t
is a step fraught with many possibilities,
chief of which is the fact that the cleo
trostatic qualities of the porcelain may
be impaired The decorations are printed
on gauze paper and pasted on the poree-
lains by girls, after which each label is
buffed with a revolving brush, which
firmly fixes the imprint on the glaze. a
plunge into warm water removes the pa
per- and the decorated porcelalnS are
arranged on trays and placed in muifter
type furnaces having a capacity of %
600 each Here they are brought to 4
red heat. and when sufficiently baked
and cooled, are ready for the actual
work of making spark plugs, their func-
tion being chiefly to carry the hair-like
platinum wire which forms the insulated
sparkling point, the copper duill ana
spring and other accessories employed
in this portion of the completed mechan-
ism, and which is of interest only to the
technically inclined. Al every stage there
Is inspection. and finishing touches are
given wherever necessary.
In the assembling-room the porcelain
and metal parts are brought together,
the plugs assembled, and each given d
test before leaving the factory. Discus
sion of the metal work is unnecessary at
this time. for its duplicate might be wit
messed in many plants. so far as the
processes are concerned However. IN
passing it might be well to note that at
least one item entering into a spark plug
IS guarded as carefully as would he dia-
monds. This is the platinum wire used
i'm the sparkling points, which more than
anything else resembles hair, and costs
the modest sum of $50 or thereabouts for
an ounce.
Two years ago quartet of energetic