4 
liERAMIC STUDIO 
GRAND FEU CERAMICS 
X— FIRING-Neuter, Oxidising, Reducing 
Taxile Doat 
THE fuel adopted for decorated porcelains is wood. Trials 
with" coal have so far only given negative results, what- 
ever the claim of some ceramists, who, in talking, have solved 
every problem, but whose exhibited works do not show any 
solution at all. What matters anyway the extra expense of 
using wood in an artistic production? The important point 
is to have a tractable fuel. Until the coming of a chemist who 
will obtain wdth coal the fresh and brilliant palette which 
wood gives, I will conline myself to the fuel of which 1 am 
about to speak. 
The two principal species of trees are oak, the king of the 
forest, and the himible birch with its gay white bark. The 
kind of oak generall^^ adopted for firing is the yoimg oak, the 
bark of which is used by tamiers. This tree falls by itself 
under the action of the sun, after longitudinal incisions have 
been made in it by foresters. But whether young or old, small 
or large, straight or knotty, oak can be used. Large trunks are 
cut into sticks of equal lengths. Large sticks are fed during 
the first part of the firing; those of medium and small size 
during the second part or petit jeu. It is important to throw 
into the fire mouths charges of equal volume to obtain the 
necessary regularity in the increase of heat. 
Oak has been adopted in Limousin, Vierzonnais, at 
Sevres and by all artists who decorate their works with grand 
few colors, because on account of its close grain, it burns slowlv 
and evenly. Its action is progressive, w-ithout rushes. Birch 
acts quite differently. Large trunl^s niust Ije discarded, 
because of the slow work of their splitting. Birch four and five 
3'^ears old, in medium and small sizes, is the best. It nuist be 
sound, straight, without knots or rotten spots and ]3erfectly 
dry. It should be cut two years before being used. 
It is sawed in two, its lengths being about 45 inches (this, 
im, 15, is the length generally adopted for the cutting of wood 
in the French forests) . These sticks are then split into pieces 
of even size. For instance, a stick 3^ to 4 inches in diameter 
will be split into six pieces; that of 2 to zh inches into three; 
that of i-i to 2 inches into two onty. A regular splitting 
allows one to feed evenly and to regulate the combustion. 
During the grand feu firing, birch is used exclusive^. Its 
loose grain allows it to Imrn instantaneously when placed on the 
hopper of the fire mouth. It gives a long, clear, intense flame. 
The basis of 45 inches being adopted for French cuts of 
wood, the wood will be cut with two or three sawings, according 
to the width of the fire mouth, as an}^ false cut and consequent 
loss of wood must be avoided. The fire mouths of my kiln wood 
being 17-i- inches wide, oak is divided in four pieces by three 
sawings. It could be divided into only three pieces with two 
sawings, but its division in four allows me to fill the fire mouth 
better. Birch is divided into t\^o, each piece being then from 
22 to 2T, inches long. 
I have said elsewhere that after 3 or 4 firings, repairs 
sometimes of importance must l3c made to the kiln. The new 
masonry nmst be dried tmt. To obtain this result, a brazier 
is lighted for two da3\s and two nights in the firing chamber. 
This brazier is made of placing rings superimposed, about an 
inch apart. When the kiln is entirely new this brazier must 
burn for about 10 daj's, as it is most important to have a kihi 
perfectly free from moisture. This drying is eft'ected with coke. 
Whatever care is given to the construction of a kiln and to 
the firing, it is impossible to have the same temperature in 
every part of the kiln. Naturally, the part which is close to 
the fire mouths is subject to a higher temperature than the 
part where the flames leave the firing chamber. I have 
stated that there might be the enormous difference of 50X. 
between the temperatures of the bottom and the vault of the 
kiln. It is extremely important to reduce this dift'erence and 
to get as nearly an even temperature as possible by a pro- 
gressive firing, without any rushes of heat. The firer should 
be constantly on the watch, especially during the grand feu. 
The kiln is lighted by placing ten pieces of split birch in 
the bottom of the fire mouth, crosswise. On top are placed 
two round sticks of medium size oak. At the same time the 
stojiper of the opening A at the base of the chimney (Fig. 50, 
page 228, Feb. 1904) is removed. A handful of chips or kindHng 
wood is lighted there to displace the column of cold air which 
is in the chimney and to start the draft. The fire mouths are 
covered with a sheet iron plaque (Fig. 80) in the middle of 
which is a long iron stem for a handle. The draft is immcd- 
iatel}' established without any smoke getting into the room. 
If there is a baking chamber, the opening for starting the draft 
may be established in the door of this at the foot. Chips and 
kindling wood should be kept bimiing there luitil the draft is 
well started. 
The time of firing a porcelain kiln is divided into three 
distinct divisions: the drying, the petit feu and the grand feu, 
or slow, active and grand feu. 
The object of the drying is to remove all moisture which 
the kiln itself or the placing material may contain, either from 
dampness in the ground or in the atmosphere. I give the 
records (Fig. 89 and 90) of two of my wood firings so that it 
will be easier to follow everv^ phrase and to luiderstand better 
the action of the dift'erent parts of the kiln. 
The drying lasts from 3 to 4 hours during wdiich, everj- 
half hour, two large sticks of oak from 7 to 12 inches thick, or 
their equivalents, five round sticlvs about 2 inches thick, are 
placed crosswise and in good order, in the bottom of the fire 
mouth, as close as possible to the firing chamber. After three 
hours, one more large stick or its equivalent in small round 
sticks is added at the same interA'als. 
The drj'ing being finished, one begins the active firing or 
petit feu, during which the heat must gradually penetrate the 
masses of placing material and the pieces thej- contain, all 
sudden rushes of heat which might cause cracks being carefuUy 
avoided. The petit feu is obtained bj' feeding one more big 
stick of oalc or its equivalent in small round sticks every 
twenty minutes, without any special order. After seven to 
nine hours of this firing, the entire mass of the jjorcclain and 
the saggers has been penetrated and there is nothing more to 
fear with regard to breaks and cracks. The firing can now 
progress boldly until the fire mouth is full. By keeping it 
thus full, the Iciln soon becomes red, as can be noticed by look- 
ing through the door spyhole. When the kiln has changed 
from dark red to cherrj' red, the grand feu has begun. 
Before one becomes quite faauiliar with these two jjhases 
of the firing, and has learned by practice to obtain the cherry 
red in the time mentioned, it will be important to start the 
