RERAMIC STUDIO 
55 
maiw substances, so that they will be intimately mixed and in- 
corporated with each other. It is made in a fire clay crucible. 
This crucible, containing the substances to be fritted, is placed 
in the hottest part of the kiln, where it passes through the 
different temperatures of the firing and undergoes a partial or 
complete fusion. If there has been only calcination, the 
crucible, when taken out of the kiln, is simply emptied, and the 
calcined prodvxct mixed in the mill. But if the materials have 
fused, they are stt;ck to the crucible, which must be broken, to 
allow the gathering of all the vitrified substance which then will 
be crushed and ground, and will be used in the shape of im- 
palpable flour. It is in the upper part of my kiln that I place 
the crucibles. If the mixture is liable to overflow, an old bat 
should be placed under the crucible to protect the placing 
material. My crucibles are made of placing material (Provins 
clay and grog) and have the shape of Fig. A, with a spout. I 
Intimate [Clayey kaolin 20 
mixture I PN white paste 85 for oxidising and reducing 
[Frit 30 firings. 
Mauve Paste 
f Chrome aluminate 30 
Simple 
mixture ; Feldspar in flour 
I PN white paste 
20 strictly oxidising firing 
30 
Strong fritting 
Black Paste 
[Clayej' kaolin 
^j Chromate of iron 
Cobalt oxide 
50 
6 
Mixture 
) PN white paste 
^Frit 
75 
30 for oxidising 
firing. 
Grey of Platinum Paste 
buy them from Mr. Pollard, rue du Poteau No. 59, Paris. The 
most useful are about 8 inches high and 4 inches in diameter.* 
Dark blue paste is obtained bj' thoroughly mixing in the 
crucible and fusing moderately the following materials : 
Fontainebleau sand 54 
Frit Pure and very white clayey kaolin 45 
Cobalt oxide free from nickel it 
This frit crushed and ground is mixed with the paste in the 
following proportion: 
Clayey kaolin 45 
PN white paste 71 both for oxidising and re- 
Frit 57 ducing atmospheres. 
A moderate fusion can be obtained by placing the crucible 
at the bottom of the kiln, a strong fusion by placing it on top, 
of course in a down draft kiln; inversely in an up draft kiln. 
For some very weak frittings, I have made a hole in the 
bottom of the kiln. Protected by a deptli of a foot the crucibles 
receive a very mild heat. As much as possible I avoid fritting, 
bvit it must be admitted that it is the surest way to obtain a 
thorough incorporation of the coloring matter with the paste 
and their intimate mixture. Pastes which have not been fritted 
have a rough appearance and are sprinkled with spots, which 
are not shown on fritted pastes. The latter harmonize better 
with the precious porcelain material. For this reason fritting 
is to be recommended, but it is slow and expensive. 
Blueish Green Paste 
I Fontainebleau sand 
Pure clayey kaolin 
Chromate of cohalt 
To be mixed by grinding in a hand mill 
powder is to be had. 
(Clayey kaolin 43 
PN white paste 90 for oxidising 
Frit 55 
Green Paste 
fFontainebleavi sand 30 
J Clayey kaolin 25 
I Feldspar in flour 75 
[ Chrome oxide 20 
30 
22 
7 
if no motive 
firing 
Very strong 
fritting 
*The plumbago crucibles of the Dixon Graphite Co. are excellent. 
Light grey. Dark grey. 
Simple ) Platinum oxide 2 Platinum oxide 6 
mixture \ PN w'hite paste 98 PN white paste 94 
for oxidising and reducing firings, very fine tone in oxidising. 
In all these formulae, the PN body may of course be re- 
placed by any other porcelain paste which will be adopted. 
But one must carefully avoid putting a color made with a 
certain paste over a paste of a dift'erent composition. It is 
better to use for these color mixtures, not the fresh porcelain 
paste, but the scraps of paste which are gathered on the wheel 
after throwing. They have the advantage of having been 
worked and being more plastic. 
The pastes w4iich I have mentioned do not stiit gres, as its 
coefiicient of expansion is different, besides they give on gres 
only neutral, grey tones. They are exclusive to porcelain. 
Colored pastes are applied either on raw or baked pieces, 
quite thick, in successive layers, each layer being dried. They 
are applied either with the decorating brush or with a fine 
sponge when large surfaces must be covered. To lay the paste 
in one coat would be to surely produce crackles and blisters. 
,,It must be laid very carefully in the shape of very thin slip for 
the first coat, gradually thickened for the following coats. It 
is mixed in water without the addition of gum. 
Over these pastes, which are not displaced in the firing, 
can be made, by a superimposition of white paste, the fine 
bas reliefs, which are called pates sur pates, and are known 
everywhere. 
When the design has been traced over the colored paste, 
either with a pencil or a pouncer, it is covered with slip of white 
paste laid in successive coats and of different thicknessses 
according to the effects to be obtained. The water is absorbed 
by the raw body and the paste is gradually deposited. When 
the desired thickness is acquired, the paste, thoroughly drj^ is 
modelled with an iron dented chisel such as is used for medal 
engraving. During the firing the coloring oxide of the under 
paste penetrates the white applied paste according to its 
coloring power and gives it in the thin parts a transparency 
which reminds one of the precious effects of cameo. Blue and 
green pastes possess the greatest penetrating power. For 
thifj reason bas reliefs executed over these pastes must be made 
thicker. 
Colored pastes being opaque are naturally mat after 
firing. To give them the necessary brilliancy and glassy 
finish they must be covered with a glaze, which will preserve 
them from the injuries of time, and distinguish them from the 
bas reliefs made in Wedgwood style. 
[to be continued] 
