TILE-MAKING
"VI thousand and fourscore of pavynge tiles delivered at Hampton
Court, for to pave the Kinges new hall at XXVJs. VIIJd. the
thousand."
--Sixteenth century memorandum.
Tiles may be made of various kinds and sizes, but in every case they show
an inclination to buckle in drying and firing. The larger the tile the
stronger is this tendency to warp. The clay must not be so rich as that
which is used for throwing and should be tempered to counteract the
tendency to curl.
A tile box as shown in Fig. 39, or a variant of it, will be required for
pressing tiles by hand; for plain tiles 5/8" deep, for others 1-1/4" deep,
the size being calculated to allow for shrinking. The sides hinge and the
thumb screws keep it steady on the bench during work. For rough tiles, two
strips nailed to the table will serve, the clay being rolled out between
and cut in lengths as required.
For plain tiles the wedged and tempered clay is batted out into a slab a
full 3/4" thick. The mould is dusted with French chalk, flint, or very
finely sifted clay dust, to prevent sticking, and into it is pressed a
piece cut to fit easily in the tile box, from the slab. This is firmly
pressed into the box, considerable pressure being used. The surplus is
scraped off and the top trued with an iron straight-edge. The knife can be
run round the sides, then with the frame reversed a smart tap on the back
will release the tile.
[Illustration: FIG. 39--TILE FRAME--6-1/2" x 13".]
Let the tiles toughen and then pile in stacks with flat pieces of clay or
old tile between each corner and a true biscuit tile at bottom and the
top. They can be piled one on the other with sand between or stacked like
bricks with alternate holes for the air to circulate. This retards the
drying, but in any case they must be dried slowly. With plain glazed tiles
a little coarse dust sprinkled over the surface before the tile is removed
from the box, and well pressed in, will give a slight interest to the
surface and take away any mechanical look. If required for painting, the
clay must be very finely sieved and the surface will need careful
finishing by hand when dry. With coarse clay, a fine surface can be
imparted with a flexible broad palette knife.
For raised outline tiles a frame 1-1/4" deep is required. This allows a
plaster bat 5/8" thick to be placed at the bottom. The best way, perhaps,
is to oil the frame and cast the bat in it, removing it when set and
sandpapering the upper surface flat and true. The design for the tile
drawn the exact size on paper is now traced on this surface. It is far
better to sketch it directly onto the slab, but this demands some
proficiency if the surface is to be preserved. The design is then incised
with a firm sharp point, clay squeezes being taken from time to time to
show the progress of the work. The plaster should be wetted to insure easy
working. At the finish the design should stand out in a fairly strong and
deep line--square--not round or angular in section. (Fig. 40.) A
chisel-pointed hard pencil will be found best for finishing. This gives a
clear-cut line, not too round. The bat, sponged clean and porous, is then
placed in the frame and the tile pressed as before.
[Illustration: FIG. 40--A: POINT FOR FIRST OUTLINE. B: DO. FOR FINAL
INCISED LINE. C: SECTION OF INCORRECT CLOISSONS. D: CORRECT.]
Raised outline tiles can be even more satisfactorily made by means of
outlining slip squeezed from a tube or tracer in the same manner that
inscriptions are made on sugared cakes, but this requires much practice to
obtain good results. When glazing, the coloured glazes are applied to the
different compartments with a brush. As the glaze fuses to about one third
of its bulk when dry, it should be applied very liberally.
It will be found that large or elaborate designs are to be avoided, as in
this process they tend to become mechanical and look thin. The old
Spanish and Moorish tiles in this style with jewel-like bits of colour are
excellent guides and might be studied with advantage.
[Illustration: FIG. 41--SLIP TRACER.]
The process of making encaustic tiles is a little more complicated. Within
the frame is placed a well-lathered or soaped plaster bat (or tile) high
enough to allow only a thin layer of clay 1/8" thick being run out on top.
On this when firm the design is traced or pounced. Then with a thin sharp
blade it is cut down vertically to the plaster bat, and the clay removed
until the whole design shows in white plaster beneath (see illustration
42). The face of the clay left must be preserved carefully, as it forms
the surface of the subsequent press.
The bat with clay is now placed on the bottom of the frame to allow a cast
5/8" thick to be made. The plaster and the sides of the frame are slightly
oiled and the plaster mixed and poured in. A soft hair brush will be
useful to dislodge the air bubbles that are certain to hide in some of the
many odd corners. When nearly set, the surface of the plaster can be
scraped flat, and when set taken out of the frame and detached. The clay
is picked out and the whole surface of the design cleaned and trimmed so
that it will not hold or bind in pressing. This in turn is placed in the
frame and a careful press taken. The result is a sunk design into which a
different coloured clay is pressed, the tile being first allowed to
toughen. The surface is lightly scraped flat and the tile slowly dried.
When hard, the face is scraped again with a steel straight-edge,
sandpapered, and dusted, when the design appears in two colours. (Fig.
43.)
[Illustration: FIG. 42--CLAY LAYER CUT OUT ON BAT & PLASTER DIE.]
The most effective clays are fairly siliceous reds, buffs, browns, and
greys. When tempered with flint or quartz sand to a uniform degree, they
offer a splendid opportunity for counterchange pattern. If a soft clay
that contracts considerably is inlaid in a refractory clay, cracks will
appear round the edges of the inlay. Thus it is found best to have the
body of the tile made of the clay that contracts most.
[Illustration: FIG. 43--STRIKING OFF FACE OF TILE IN FRAME--SECTION ON
A-B.]
Where only a single tile is required a more direct method is possible. The
tile is pressed and allowed to toughen slightly, the design being
transferred as before. It is then cut round with a sharp knife and the
waste removed with a wire tool. A certain facility of handling is
required, for great care must be taken to preserve the edges and angles.
This method is, however, productive of much fresh and vigorous work.
Encaustic tiles must necessarily be simple and bold in character, for
anything complicated invites confusion; the best possible guides are the
encaustic tiles of mediæval times, especially the simple and spirited
English and German Gothic.
The most satisfactory way to make modelled tiles or panels is to run out
upon a stout board, cross battened to prevent warping, a flat slab of clay
of the required thickness. Sketch in the design with a point and model
straight away onto the clay. Care must be taken, if the panel is to be
fired, to see that all the added work adheres firmly to the background.
Where several presses are to be made, the edges of the modelled slab
should be carefully trimmed with a bevel, the board oiled, and the mould
made directly after the modelling is finished. The mould may be worked on
in moderation. Lettering is much more easily incised in the mould than
raised in the clay. For tiles needing much sharpness of detail almost the
whole can be carved in the plaster. Unless done with great sympathy,
however, this leads to a certain harshness and angularity that should be
foreign to clay. Where a moulded frame for a panel is required, a
_strickle_, or profile, is cut in zinc. For short use one made from a thin
slab of plaster will serve. The strickle is keyed to a straight-edge and
dragged over the clay until the correct moulding emerges. This is then cut
into lengths and very carefully dried.
The tendency of all transparent glassy glazes to pool in hollows and run
off at high points must be borne in mind. With thick matt glazes any
delicacy of detail is apt to be lost labour. These problems should be
faced before the design is made, as in this process there is a certain
quality of surface required by the glaze. On the other hand, in
endeavouring to make a good surface for the glaze to enhance, it is easy
to slip into the over-round and slimy treatment that characterizes so much
modelled pottery.