The history of brick covers such a vast span of time that it is a major problem to decide when precisely its industrial production began. Should the criterion be the manner of production, such as the purely mechanized methods of today, or is not the decisive factor indeed the volume, the number of such products, the scale of brick consumption and production?
If we think back to the Tower of Babel , the archaeologists have produced evidence that an estimated 85 million bricks were required to do this. There is also testimony showing there was an extensive division of labor for the work. This undoubtedly represents an early form of industrialized production and was most certainly the culmination of a long pre-industrial period dating back to the first human settlements in the various continents. A history of the brick and tile industry therefore, however cursory, must cast the net far back into those early epochs.
It is established today that the earliest cultures arose in the large river valleys of the earth, where indeed the raw materials necessary for brick making were always to be found in abundance. We are quite right therefore in assuming that the art of brick making first originated there. The areas most thoroughly explored and hence the best known are those cultures which flourished in the valleys of the Nile and of the Euphrates/Tigris, particularly in the lower course of these rivers. Archaeology in its heyday during the last century and still to some extent today has been mainly concerned with those forms of development dating from a period when artifacts of cultural value first made their appearance. The less conspicuous finds and indeed less easily decipherable phases of earlier periods of history were in many cases neglected. Consequently it is only in very rare instances that such vestiges can be found at all today, let alone traced back to their origins and their meaning unraveled.
If we consider this fact in the context of existing knowledge derived from excavations in the river valleys of Egypt and Mesopotamia, we can see that even prior to the most ancient finds, e.g., in Ur of the Chaldees, technology must have evolved from even more remote times to make it possible to construct such highly sophisticated wall reliefs of moulded clay. It may be assumed that just as in our latitude later on technology was primarily evolved for purely utilitarian ends, i.e. brick production for houses which must have preceded the erection of those religious and prestige buildings and fortifications by many centuries.
Deep excavations carried out for technical reasons in the Nile Valley have revealed remains of old building settlements buried under layers of silt and mud several meters deep and ruins of early small dwelling of unfired loam bricks. These bricks, mixed with chopped straw, could be early identified as having been moulded in dimensions comparable to our standard size, i.e. for manipulating by hand.
From the number of overlying layers of mud and from Carbon dating, the age of these remains can be assigned to a period ca. 13 000 B.C. As no older remains of the same type and capable of dating have so far been discovered on earth, these archaeological finds in Egypt represent the earliest evidence of brick making activity in the history of the world. We know of illustrations, such as those of Mustafa Rekhmireh from the middle of the 15 th century B.C., showing 21 laborers occupied in the different brick making processes, from fetching the loam from the sump to the stacking of the finished bricks. A whole range of tools is also depicted. These early finds also include brick stamps, usually in the form of royal cartouches confirming the exact date.
As well as from Egypt , we also have precise documentation on the making of bricks from the country regarded as the most characteristic of the use of plastic clay, i.e. Mesopotamia . It differs essentially from Egypt however in using at a very early date not only unfired bricks but also bricks fired in kilns. For the vast temple towers and minarets, palaces and fortifications, a very hard and durable brick was required. It has been established with certainty today that fired bricks were already in use in 4000 B.C. and likewise that in 3000 B.C. it was possible to produce bricks in different colors.
That part of the city of Babylon lying to the left of the Euphrates was excavated between 1877 and 1917 by the German archaeologist Robert Koldwey. He has workers' huts built from bricks turned up in the excavations. These are still standing today. The bricks are hard and sharp-edged and technically, there would be no objection to their use in a modern building.
As mentioned earlier, it is estimated that some 85 million bricks were needed to build the Tower of Babel, certainly the most famous brick work structure in the early history of the world. Although there were still no building industry in our sense of the world, the enormous number of bricks used compels us to think on an industrial scale, even though brick making was still by hand but already largely rational in its division of labor. What enormous technical development must have preceded the conception of brick architecture on such a vast scale and its realization. This expert knowledge endured for thousands of years, although all the cultures of Asia Minor - of the Assyrians, the Persians the Sassanides and Islam. There were a myriad encounters in different ways between East and West over their thousands of years' history, sometimes together, sometimes going their separate ways. Frequent testimony has been handed down to us of the exchange of technology between them. No other building material has assumed a pre-eminent position in all civilizations as brick.
Admittedly there are periods and areas in which brick was overshadowed by other materials, for instance in Greece where marble was available in abundant quantities and outstanding quality. Brick making was pursued here too, however, as is testified in an account by the Greek writer Pindar, in the 5 th century B.C., who attributed the invention of the clay roofing tile to the Corinthians. The principle of using fired clay tiles for roof covering and the forms of tile employed have scarcely changed from that day to this. Eaves, antefix and ridge tiles were found then up to 50 cm wide and 80 to 100 cm long. Wilhelm Dörpfed reports: "The roof ridge is covered with massive, curved tiles with recesses for the interlocking of the roofing tiles."
The Romans, who subsequently instructed Western Europe in brick making techniques, took over most forms of Greek roofing tile. They themselves also produced a large number of different tile shapes, culminating in the curved, interlocking tile. Vitruvius and Pliny put forward suggestions for brick and tile standards, but the Romans were far too great individualists to allow their style to be cramped by standards. One feature common to all the Roman tiles so far discovered however is that they are comparatively thin, 2-3 cm only, which is presumably due to the problems arising in drying and firing greater thicknesses.
In the Western world, the Romans in fact acted as missionaries for the propagation of brick and tile production and the use of this material for building. Wherever their military campaigns took them, they brought brick building with them to Spain , France , England , Holland , Belgium and Germany . In the latter especially along the Limes, the Roman line of fortification a whole series of brick works of the Roman Legions have been found, in some cases excavated in their entirety. This gives us a very good idea of the technical conditions prevailing at the time. Bills have been found, scratched for simplicity on the brick themselves while still soft. These provide evidence that a laborer's daily output was 120 to 140 large-size bricks and 220 to 240 standard bricks. It is assumed here that the legionaries detailed to carry out brick making had to dig and prepare the clay themselves, as in the 19 th century their descendants in German brick works attained the same rate per hour, excluding ancillary works.
Apart from the military brick works, there is also evidence of private works which were so productive that they were able to supply the immediate hinterland and even more distant areas. The brick works discovered at Abbach on the Danube shipped its products up to a distance of 100 km. Proof of this is furnished by the brick stamps, which also provide other historical data. The same applies to Bregrenz where a kiln supplying stamped bricks was found. Bricks from this kiln of "Carinianus" were found even in Augsburg and Grundremmingen.
If we consider the technology of Roman brick making, we should mention that the clay body was usually thoroughly prepared and, if necessary, incorporated a sand opening agent. Vitruvius already gives more precise information on the preparation, the moulds used and the drying of the handmade bricks. These were produced only in the spring or autumn, as in the summer the surface dried out too quickly which was liable to cause frequent cracks and other defects. This was the situation in the warm south. In the north there is evidence to show that brick making was in fact carried out during the hot summer months, as was customary in our latitudes right up to the end of handmade brick making. Firing was performed with wood in the traditional clamp or scove kilns.
During subsequent centuries people naturally tried by every means at their disposal to replace the heavy manual labor involved. Water power, horses and oxen were used to drive simple rolling mills and the precursors of our present day pan mill. The English, after the invention of the steam engine by James Watt, were to first to employ these new power driven machines for their grinding and roller mills and hence to introduce industrialization as we understand it today.
In 1769 Watt was granted the first patent for a steam engine. In 1792, Watt constructed the first machine with piston rod and centralized control. The preparation machines, which required a large amount of energy, were to first to benefit from the newly invented steam machine. Shaping continued to be carried on in the age-old tradition of hand-throwing.
At a very early date, however there were a number of attempts to employ other means for easier preparation of the clay body and even the hand-moulding of bricks themselves, both involving heavy manual labor, by use of simple machines driven by water-power or animals.
Thus Henry Clayton in 1844 developed a form of vertical pug mill, a refinement of the ancient Dutch clay mill, the "kleymühle".
Efforts to develop machines for shaping should also be mentioned. Chronologically these were roughly as follows: In 1799 Kinsley developed a device imitating the hand moulding of bricks. A mould was pushed under the pug mill, the clay was forced into this by a press and then ejected by a punch-type mechanism. In North America Doolittle in 1819, Delamoriniere in 1824, Carville Issy in 1840 and Huguenin and Ducommin in 1844 constructed similar machines on the same principle.
In 1827 Cundy constructed a machine for pressing individual units from a clay slab. Other machines of this type also include those of Bosq (1829), Vivebert (1831) and that of Bosfort (1844) which also simultaneously applied decoration to the tiles.
These early brick and tile making machines attempted at the beginning of the 19 th century to imitate hand moulding by mechanical means. These machines were later on in fact introduced to Germany from North America and Holland .
It was not until the invention by Carl Schlickeysen in 1854 of the screw conveyor for transporting plastic masses however that the way was open for the development of a viable brick making machine. Schlickeysen's worm or screw extruder for shaping the clay constituted the basis for the highly sophisticated brick and tile industry today.
In 1874, 1881 and 1883 there followed the patented inventions of the feed roller, interchangeable cutting blades and mixing and homogenizing augers. At the international exhibitions in London , Paris , Vienna , Philadelphia and Berlin , the newly perfected horizontal extruders for the clay column received over 30 awards. The rotary inventions of Schlickeysen thus first made brick making possible on an industrial scale. Brick making ceased to be a minor branch of the rural economy and became an industry in its own right. The brick making extruder entered upon a triumphal progress throughout the entire world and brick making grew into a mighty industry.
At approximately the same time another invention opened up the way to modern mass production: the kiln operated on a continuous firing cycle. The very earliest kiln of this type came from England where Aynsley Brick and Tile Machine Company had taken out a patent. This consisted however of a series of individual kin chambers. The decisive breakthrough came with the ring kiln of Friedrich Hoffman for which he was granted a Prussian patent in 1858. Hoffman built the first ring or annular kiln at Scholvin near Danzig - initially circular in form - but later on, to save space, rectangular. This continued in general us until the annular kiln was gradually superseded by the tunnel kiln. Hoffman received the Grand Prix for this at the World Exhibition in Paris in 1867. Patents then were taken out in many other countries and eventually Patent No. 11 534 in the United States in 1871.
Inevitably attempts were also made to tackle the last, still unsolved and cost-intensive problem of brick making, i.e. drying. In 1895 Keller constructed an experimental plant comprising the first chamber dryer in combination with finger cars. As the heat source he used finned tubular heating pipes operated with waste steam, live steam or hot water.
Difficulties arose in the removal of the spent, moisture-saturated drying air, which was performed by natural escape via roof slots, a suction channel and waste stack. There was very little means of regulating this equipment, however, because the natural draught of the exhaust stacks was dependent on the external air.
With the introduction of artificial or exhauster draught, automatic regulation was possible and hence freedom from independence on weather conditions.
Jacob Bührer, himself from a brick works near Schaffhausen, was concerned from his youth onwards with the problem of drying. Already with the intermittent or periodic kiln, he extracted heat for drying purposes using a water powered wooden fan. Later on, he constructed the first chamber dryer in his father's brick works for which he obtained the heat by means of a suction fan. The first large scale plant using his system was erected by Bührer at the Münchner Aktienziegelei at that time, consisting of the longitudinal zigzag kiln, also developed by him, and a flue gas dryer with suction fan. Interested viewers from all the leading countries flocked to see the new Bührer works.
The principle creation of Bührer is in fact this suction fan, combined with the shortened zigzag kiln and with the fast firing process, likewise introduced by him and innovation of major importance for the national economy. He demonstrated in practice that it is possible, depending on the type of raw material employed, to complete the firing process very much more quickly than in the past.
With advances in the development of machines for clay extraction and preparation and the introduction of the vacuum de-airing extruder and the tunnel kiln in the heavy clay industry, we now approach the end of the evolutionary period of brick making technology.
The first practicable deign for a tunnel kiln in the ceramic industry was by Otto Bock in Brunswick , who in 1877 was granted German Imperial Patent No. 1340 and who had the distinction of being the first to introduce the first kiln for the continuous firing of clay products. He thus set in motion process of development which still not completed today.
This applies to all plant and equipment used in the heavy clay industry at the present time. When one visits a brick or tile works today which was erected ten or even five years ago to the very latest design and compares it with the most recent production works, now fully equipped with electronic controls, one wonders indeed where history ends and the present day begins. And this will continue to be the case in the future.
Reference: Bauverlag GmbH: Brick and Tile Making 1982