Improvements in the Manufacture of Bricks, Terra-cottas, and the like.
Year: 1893

page_text: Date of Application, 21st Nov., 1893-Accepted, 23rd Dec., 1893
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Bricks, Terra-cottas, and
the like.
I, CARL SCHLICKEYSEN, of No. 17, Wassergasse, Berlin, Engineer and Manu-
facturer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :—
In the manufacture of bricks, or facing bricks or blocks, terra-cottas, and the
like, by processes heretofore employed, it has been almost impossible to prevent
the appearance of white and yellow spots or discolourations on the products,
resulting from the action of salts and acids. After burning the bricks, their facing
surfaces often shew such an amount of discolouration that they are either useless or
can only be rendered available by expensive treatment, either chemically or by
coating with colour.
The present invention relates to an improved manufacture whereby perfectly
pure-coloured products are obtained, so that any subsequent cleansing or other
treatment thereof is entirely obviated.
The improved process for producing facing bricks, terra-cottas and the like, has
more particularly reference to the arrangements for drying the products after being
moulded and before being introduced into the burning kiln.
If the process be employed in the manufacture of ordinary bricks, or facing
bricks, these according to one arrangement, are, on issuing from the press mould,
cut through horizontally by a stretched wire or other device at about 3rd inch
from the bottom in such manner that the cut-off slab only slightly adheres to the
brick. After removal from the roller-table the bricks are turned over by known
appliances and are so placed on the drying board or supporting surface that the
separated loosely adhering slabs are situated at top, while the facing surface is at
bottom.
The drying boards must be kept very clean, and all earthy particles, salts and
acids that may adhere thereto, be carefully removed.
The slabs lying loose on the bricks and which are more exposed to the air
currents, dry quicker than the bricks below, and, as has been proved by experiment,
draw by degrees the whole of the moisture including the salts &c. dissolved therein,
from the bricks.
The process of drying takes place in such manner that the upper layers of the
brick material, which are more exposed to the action of the air and are consequently
always somewhat drier than the lower layers, draw up the moisture with the salts
and acids &c. from such lower layers, so that the moisture &c. is gradually drawn
upwards from layer to layer.
Before the article is burnt in the kiln, it is freed from the slab lying upon the
same, which slab now contains the salts that have sweated or crystallised out.
If it is not desired to collect the chemically separated matter in a slab separable
from the brick, this slab can be dispensed with.
In this case the moisture with its chemical constituents will collect in the upper
layers of the bricks, so that these separated matters can only show themselves on
the upper back face of the bricks.
The bricks may also be moulded of the ordinary section and when laid upon the
drying board, slabs of a different clay material, either moist or dry, be laid upon
them.
In order to obtain the perfectly clean drying boards or surfaces required for the
new process, it is advisable to cover them with paper free from salts or acids, on
which the front faces of the bricks are then laid.

page_text: By means of this paper also, the access of the air to the said surfaces of the
bricks is prevented, and the moisture is retained for a longer time in the lower
layers of the bricks so that the drying of the lower part is retarded and is mainly
effected by the drawing up of the moisture and the salts, acids &c. dissolved therein
by the upper layers.
The drying of shaped or ornamented facing bricks or blocks or terra cottas can
be effected in the same way, but in order to obtain the facing surfaces as pure as
possible it is preferable to effect the drying in such manner that all facing surfaces
as also the side surfaces are covered with paper, wadding &c., and the product then
placed with its bottom side upward for drying.
In this method the facing surfaces, with the paper applied thereto, can be placed
upon or in a soft bed such as sand, wadding, powdered gypsum, rags &c., care being
taken that the back surfaces of the articles are freely exposed to the air currents.
The back surfaces may in this case also be covered by slabs of the same material
or of a different material, which are removed before the burning. The drying
may however be also effected without such slab, and the salts, acids &c., be
allowed to accumulate in the back surfaces of the articles, as already described.
On the accompanying drawing Figs. 1 to 6 shew by way of example the manner
of carrying out my above described invention. Fig. 1 shews the front view of the
mouth or die of the moulding machine. Fig. 2 shews a side view thereof, Fig. 3
shews the brick placed upon the drying board, while Fig. 4 shews a decorative
facing brick or block being dried according to this invention in a free standing
condition, Fig. 5 shews such an ornamental brick or block bedded in a layer of
sand, Fig. 6 shews the drying of an ornamental brick or block in a bag filled with
soft material.
The same parts are designated by the same letters of reference in all the figures.
a is the brick; b the slab separated therefrom; b' a slab made of a different clay;
c a paper strip of the necessary width, entirely free from earthy particles, salts
and acids; d are the rollers on which the brick column coming from the
moulding press runs in the usual manner; e are drying supports; findicates a
stretched wire in front of the mouth of the press which serves to separate the
slab bg indicates the moulding press; his the soft material with which the box
or bag is filled.
As shewn at Fig. 1, the brick column a in coming out of the press, is cut through
at about 3rd of an inch from the bottom by means of the wire f, but the separated
slab 6 still remains slightly adhering to the brick.
The blocks are then turned over by means of wooden forks or other appliances
and are placed upon the drying boards e, the slabs 6 being allowed to remain upon
the upper surface.
Fig. 3 shews the above mentioned paper c placed between the drying board and
the facing surface of the brick a.
This paper will retain the moisture of the brick a somewhat longer in the lower
part thereof while the slab 6 will dry quicker and will gradually draw up and
absorb the whole of the moisture of the brick a, together with the salts and acids
dissolved therein.
Fig. 4 shews a terra cotta brick or block for decorative purposes, also covered
on its facing surfaces with paper. In this case there is employed in place of the
slab b of the same material, a slab b' of another kind of clay. The article rests
free upon the supports e.
Fig. 5 shews a block a covered with paper on its facing surfaces, and also
having a slab b¹ on its back surface, but in this case the facing surfaces are bedded
in soft material such as sand, wadding &c. h contained in a box. Fig. 6 shews the
arrangement in which a particularly valuable block for decorative purposes is
covered with paper on its facing surfaces and is placed in a freely hanging bed of
soft material in such manner that its facing surfaces, owing to their being covered,
dry slower than the upper parts which are exposed to air currents.
Burnt facing bricks, terra cottas &c. that have been dried in this manner will

page_text: be found to possess pure-coloured facing surfaces without the slightest sweating
action.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. An improved manufacture of bricks, facing bricks or blocks, terra cottas and
the like, wherein the appearance of spots or discolorations on the facing surfaces,
resulting from chemical separations is prevented by placing the products, after
moulding, with such surfaces turned downwards and resting upon clean supporting
surfaces for drying, the moisture together with the salts and acids being gradually
drawn to the back surfaces or to removeable slabs, placed on these surfaces and
composed either of the same material or of a different clay, substantially as
described.
2. In the manufacture of pure coloured facing bricks, or blocks, terra cottas and
the like, the method of drying such objects whereby they are placed with their
facing surfaces downwards and covered with paper, wadding, and the like, so that
the drying of the lower layers may take place more slowly than that of the
upper layers, whereby the latter are made to gradually draw up and absorb the
moisture, together with the salts and acids from the lower layers, substantially as
described.
3. In the manufacture of pure coloured facing bricks or blocks, terra-cottas and
the like, the method of drying the moulded objects wherein these are embedded
with their facing surfaces, covered with paper, in a layer of sand, wadding,
powdered gypsum, rags or the like contained within a box or bag in such manner
that the back surfaces are exposed to air currents, so that the lower layers shall
dry slower than the upper layers in order that the latter may gradually draw up
the moisture together with the salts and acids from the lower layers, substantially
as described.
Dated this 21st day of November 1893.