If the kiln is raised upon a box or platform from 10 to 20 inches high,
it is more convenient to stack, and also to regulate the burner. Have
the box covered with a piece of zinc or sheet iron. Connect with the
chimney in the most direct way, using 7 in. pipe which must not taper.
If the chimney hole should be smaller, have it enlarged to this size.
Set the brackets in the support upon the side of the kiln. Fill the can
with kerosene oil and place upon the bracket adjusting the funnel so
that the oil will drop into it. Place a small piece of asbestos fibre
as large as a thimble in the iron tray in the bottom of the burner, and
keep the slide in the burner well open.
_Kilns are shipped with the clay in a green state in order to insure
safe transportation_, and must be fired in order to dry out any
moisture _before_ firing china.
Turn on the oil in a fast drop and apply a lighted match or taper to
the asbestos fibre, which has become saturated with oil and will light.
Allow the oil to flow in a broken stream for about 15 minutes. By this
time the burner has become hot and will consume more oil. At first, the
bottom of the pan need not be more than one-half covered, _always
exercising care not to feed it too fast in the beginning_. As the kiln
becomes hotter, the oil may be increased gradually and a red glow will
be seen through the mica window in the door. This will gradually
increase until the whole interior is red, also the flames may be seen
through the mica window at the top. From this time the oil may be
turned on as fast as the burner will consume it without overflowing.
Usually the first time it is fired it is best to allow the kiln to run
slowly for four or five hours or longer if necessary, and until it
shows a good red throughout the inside, and hotter than for firing
China.
The China may be stacked in any manner which is convenient. Trays and
plates may be placed on edge with small stilts between, although the
expert firer may stack safely on edge without stilts as long as the
glazed surface of one piece is touched only by an unglazed bottom or
rim of the one next. If plates are piled one above the other, it is
always safer to have medium sized stilts between them. In case of a
large Jardiniere, Vase, or Punch Bowl, place a large stilt beneath. It
is frequently convenient to stack large pieces on the side, in which
case they may be raised a little in the same way. Stack the china so
that it will not wedge at any place, and so that ventilation of air may
circulate about the pieces. Cups and saucers and small articles may be
stacked in any possible position separated by small stilts. If you wish
to use the shelves place the supports in the kiln so that they rest
securely, and place the shelves upon them. Very few firers make use of
them after they have become accustomed to stacking without.
It is not necessary to heat the kiln each time before firing, as
moisture is not expelled from fire-brick into the oven as it is from an
iron firepot. Allow the oil to flow in a small or broken stream for
about 15 minutes, and then increase a little. _The main point is to
feed the oil very slowly at first until the burner_ has become hot,
when it may be increased gradually. The first red will show in about 40
minutes. From this time on, the oil may be increased as fast as the
burner will consume it without overflowing. After the interior of the
kiln has been thoroughly red for some time it will grow paler in tone
and a glow commonly called Sunshine will spread over it. This is the
point to turn off the oil, and stop the fire. You can see whether the
gold has changed color, and whether the pieces are glazed, especially
any dusted tints. If your colors come out dull, and if your rose or
carmines are brick color instead of a clear pink, or if your gold rubs
off, you may know that you have not fired long enough. If your pinks or
carmines have turned purple, you have overfired. A few trials will
enable you to know for yourself, just the right length of time.
It takes from one hour and fifteen to an hour and thirty to forty-five
minutes. The time varies, depending upon the draught and the way the
oil has been fed.
The mistake is too often made, of firing by time entirely, instead of
being guided by the appearance of the kiln. After having fired several
times, one will have ascertained pretty nearly just how long their kiln
takes to fire, and this time is not apt to vary greatly. Yet on some
days, depending upon different conditions, it may take a trifle longer
or less time, and so let your reason, rather than the clock, dictate
the proper firing.
The hole under the door is intended for a peep hole, to see the
condition of the fire in the combustion chamber, and should be left
closed. When the chimney draft is not good a carbon may form over the
burner in this combustion chamber, and by the use of a small poker
through this hole it may be removed and taken out through the burner
without stopping the firing.
If the kiln does not seem to respond properly, and in a reasonable
length of time, you will, doubtless, find that there in insufficient
draught in the chimney. This is a most important consideration, and if
there is any cause, such as a stove, or fire-place connected with the
same flue which cuts the draught, it must be removed. If attached to
the same flue as a furnace or stove, the latter must be entirely cut
off _when the fires are out in the summer_.
Sometimes it is necessary to have the chimney lengthened or pipe added
to the top, especially if there are tall buildings or trees nearby. The
chimney or additional pipe should not have a hood or covering of any
kind. In every case, an imperfect draught is the only cause which
prevents perfect success from the start. When these conditions are
right, little or no carbon will be formed. If an accumulation of carbon
forms in the chamber above the burner, it is because the draught is
poor, and must be increased. By continuing to fire with a poor draught,
you run the risk of filling the tubes and choking the kiln, which must
then be cleared out before firing again, even if the draught is
remedied.
After firing a few times, frequently after the first firing, small heat
checks or cracks will appear in the different tubes or linings of your
kiln. This occurs in all fire-brick kilns and has no serious
significance. With kerosene oil as a fuel, no injurious gases are
formed, and no harm will come to the most delicate ware. You may fire
it with perfect safety, even if the small cracks are not filled. After
a time as the cracks become larger, and seem of some consequence, they
may be filled with a paste made of fire-clay and water. Do not merely
plaster this paste over the outside, but force it well into the cracks.
In this way the kiln will last indefinitely. Cracks are less liable to
come if a little care is exercised not to cool the kiln too fast, and
not to open the door while it is hot.
About three or four hours should be allowed for cooling, and in opening
the door be careful not to subject the china to a sudden cool draught.
Open the door only very gradually, leaving a mere crack at first, then
a little larger space, etc. The sudden draught of cool air might cause
the china to craze and crack.
A piece of soft glazed ware, if taken from the kiln while still too
warm, is apt to show a crackled or crazed glaze, and you will hear the
little crackling sound produced by the sudden contraction of the glaze.
[Illustration]
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=Hibbard Powder China Colors in Vials=
[Illustration]
=No Better Quality Made=