History of bricks
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Some of the workers were very young. The Graphic of June 1871 wrote of drunkenness in brick
yard children under ten and reported that at Oldbury,
Charles Dickens in Bleak House (1853) makes his most brutish character a brick maker, and describes in some detail the interior of his cottage, his wife’s bruises and his daughter’s laundry arrangements. Anthony Trollope in Framley Parsonage (1867) writes of a West Country parish ‘abounding in brick - makers, a race of men very troublesome to a zealous parson who won’t let men go rollicking to the devil without interference’. But however troublesome and rollicking, the brick makers of the past matched the hard-drinking railway navvies in producing results which endured and are, indeed, an important part of Britains heritage.
The British, living in a land of brick work, have long seen the brick as a symbol of solidity. We talk of an object being as hard as a brick , of knocking heads against brick walls and of sinking like a brick . We drop a brick . It is probably a hard brick , likely to break something; but in this metaphor there can be a reminder of the softness of a brick when just moulded and of the need for careful handling. To pay someone the compliment of calling him a brick , though now an entirely English expression, is believed to derive from the reply of an Eastern king to an invading army which made fun of his unwalled towns: ‘My troops are my walls and every soldier is a brick .’
The brick maker no longer symbolises the rough-living worker, but there are still brick yards in which he works in the old way. Electrically driven machines may dig out and mix the raw material, but some of the best brick s are moulded one at a time by hand. The moulders are paid by the piece and may turn out over 1,500 brick s in a day. To watch a strong young man raising a lump of clay above his head, dashing it generously into the
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mould and then striking off the surplus, offers as picturesque a sight as any in modern manufacture.
Out in the country the places of work can be picturesque, too, even romantic, with their rustic drying and making sheds and primitive kllns in a setting of hollows, mounds and hillocks. In L.F’. Hartley’s celebrated novel The brick
field, an isolated brick
yard in the fens of
‘Where are we going?’ She followed him.
‘There is a brick yard on the southern slope. It will be warm there.’
Whell they got to the southern slope, they could see smoke rising from the brick -kiln chimney. Nearby was a thatched woodshed, facing south and backing on the kiln. They
went into the shed and it was very warm. They sat side by side on a bundle of faggots. The moon beams slanted
in from the West under the low straw eaves
proprietors of country brick
yards in
About 2 per cent of Britain’s brick s are made by hand in small yards with buildings like old farm buildings, but these are the brick s which many people like to have in the parts of walls that show and high prices are paid for them. It is the hand-
* Chou Li-pO’ Great Changes in a
View of
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made brick s, with their tell-tale marks, which the many
mechanised brick factories seek to imitate. To compare such
brick s with concrete products is to realise that they are the
most natural-looking of the artificial building materials.
Although no machine-made brick
can look exactly like the hand-made article,
The appeal of brick in general seems bound up with the simplicity of the basic process. To make an experimental brick let no tool is necessary except perhaps a spade. Scoop out a lump of clayey subsoil from the garden, knead and shape it (as in breadmaking), slowly dry and then bake red hot.
Firing might seem a problem, but I have found that this is satisfactorily achieved by leaving the brick let in the heart of a solid-fuel fire which is kept going for about thirty-six hours.
The brick let is more likely to turn out red than any other
colour because of the prevalence of iron oxide in clay,
brick making material is broken-down rock of one geological
age or another and is conveniently called clay (or, by non-
geologists, brick earth); but the amount of true clay present
may be less than 10 per cent. True clay consists of alumino
silicate minerals in particles of infinitesimal fineness and is
distorted too much by heat to be useful on its own for brick -
making. It is only necessary that there should be enough of it
mingled with the mass to give plasticity, the ability to hold a
shape: the non-clay materials like sand serve the invaluable
purpose of reducing shrinkage on drying and preventing the
brick s from cracking under heat.
Some brick makers are lucky enough to be able to dig material
which naturally contains clay in the best proportion for corn-
mercial brick making. A mixture of clay and sand called loam is
one of these; another is a mixture of clay and chalk called maim.
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Less fortunate brick
makers must be always adjusting their clay to give it a suitable plasticity. Very often sand or finely ground ash is added. The blue
Water-soluble salts in the clay can cause efflorescence on the finished brick unless appropriate action is taken during the preparation and during kilning; and stones, especially lumps of limestone which swell on getting wet, can cause disintegration. One advantage of the old method of tempering clay for moulding with the bare feet was that stones could be readily located by feel and thrown out. Now they are generally dealt with by powerful crushing.
There are three main ways of making brick s, of which the socalled soft mud process is the most traditional. The clay mix
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is made into a paste by adding water, pushed into wooden moulds and at once tipped out: this operation is done by machine as well as by hand and the product is generally known as a stock brick , the term coming from the stock (or fixed piece of shaped wood) which holds the mould. Those who want stock brick s for their texture of minor irregularities and fold marks will probably not find it in the machine-moulded stocks.
In the wire-cut process, a fairly stiff mix is forced in a column through a rectangular die and cut off into brick s by taut wires. About a third of all British brick s are wire-cuts. Slightly under a half of the clay brick s are made by the semi-dry process of London brick Company in which the clay, being hard, is first powdered and then pressed into shape.
To acquire their characteristic durability, brick s must be fired for a period of days at a temperature greater than 900°C, the actual temperature depending on the clay being used. As the heat rises the character of the clay and its colour continues to change. Where brick s of exceptional hardness are wanted— brick s of the sort called engineering—the clay is fired in such a way that vitrification (or partial fusion) of the
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Simple plant for making machine-moulded brick s. On its way to the machine, the clay passes through a pair of crushing rollers to deal with small stones
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material is pushed further than usual. The making of such brick
s, and the forming in them of blue ferrous silicate, calls for careful firing because prolonged burning can easily lead to distortion brought about by the irregular behaviour of fused material. Both Staffordshire and
Variations in clays, even within the same district, lead to corresponding variations in process from one brick yard to another; and in some there must be constant experiment in adding more or less of certain materials. The necessity for every commercial brick yard to adjust its way of brick making to the clay available seems to account for the fact that no industry has fewer handbooks on how to do it than brick making—less than a dozen between 1622 and 1966.
A truth about brick
making which in recent years has taken many firms by surprise is that brick
s emerge a slightly different colour when, for reasons of convenience, a kiln is fired by gas instead of coal. A large firm in the
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Good brick
is unlike concrete and stucco in needing no maintenance or surface treatment. It is improved by weathering and even looks the better for the passage of five hundred years. It is often more durable than natural stone. The
The handy weight and shape* makes brick
relatively untiring to build with, for the workman can grasp his brick
with one hand while picking up mortar with the other; he finds it, too, a flexible unit with which to follow most drawings. Even throughout the great stone building areas of the
Having been hardened by intense heat, brick s are very good at resisting fire. Thus the metal in steel-framed buildings may be buried for safety in brick work; and it can often be seen that the flues and chimney stacks of old houses, stone as well as wooden,
* The size of a brick has scarcely changed in centuries. The most recent British Standard
is 8 inches by 4* by 2* or 215 mm by 025 by 65 (B.S. 3921)
. 12 The properties of brick
are of brick . Few brick s lack toughness, but obviously some must be used with common sense. There are less than fully-fired brick s which should not be exposed, unrendered, in the outer leaf of a wall; the otherwise robust fletton brick s are damaged by frost if laid as a coping on parapets.
But in general where brick work has failed in any respect, the fault is unlikely to be in the brick s themselves. Take the damp patch on a ground-floor wall of a country cottage. This could well be explained by such things as the absence of a damp course or the presence just outside of a banked-up flower bed. If chimney breasts upstairs are damp, the cause could lie in a lack of protective flashing at the junction of stack and roof.
It has never been a protection against rain to build with the hardest, densest brick s, for wherever water has encouragement to get in, it does so through chinks in the mortar joints rather than through the brick s themselves. In fact, brick s that are porous enough to absorb a certain amount of water actually discourage th entry of rain at the joints.
The properties of brick 13
The chances of penetration by rain are reduced to nil today by cavity-wall construction, which also gives a degree of insulation. And no water can rise up from the ground where a damp- course is built in, as is usual, just below the level of the floor.
The insertion of dampcourses, formerly of slate, had become the usual practice by the end of the nineteenth century. On the other hand, the cavity wall, with metal ties to hold it together, was almost unknown until 1912. For years this construction was specified only occasionally for the more expensive brick houses. But to the busy speculative builders of the 1930s, it was welcomed, Morris S. Whitehouse remembers, ‘as a boon and a blessing because it was almost foolproof against bad workmanship and bad design’. Unless a workman completely blocked up a cavity with mortar droppings, no water could get through.
It has been argued that the dampcourse was a more important invention than the cavity wall. The point is debatable. But it can certainly be said that while a house without a damp- course is liable to be damp whether its walls are avity or solid, a house without cavity walls need give no trouble if it is carefully built and if there are wide eaves and appropriate devices, especially below windows, to throw off water. The fact that many thousands of
All the same, quite serious failures in brick
work took place from time to time in the mid-nineteenth-century period because of skimped mortar and poor laying. Workers’ houses in
Old brick walls remain which, though still doing their job, are leaning over, cracked or bulged. The reason for such failures may become clear in the exposure brought about by demolition work. Tenuous foundations are found. Inside a misshapen solid
brick wall it may be seen that the mortar is no stronger than dust, thus allowing the individual brick s far too much freedom to shift and settle. A twentieth-century cavity wall, perhaps not forty years old, yet having an ominous bulge, will suddenly expose its fragile-looking section and with it the fact that the ferrous metal wall ties have come adrift because of rust or settlement.
brick buildings rarely develop a fault because the brick s are not hard enough. Yet since the nineteenth century the commonest laboratory test has been for their crushing (or compressive) strength. Even today the brick firms like to be conversant with these figures for their various grades of brick and no sales leaflet is thought complete without a statement of them.
Although customers may be persuaded that high crushing- strength figures indicate high quality, such figures need not be a reliable indication that certain brick s resist the weather
well or are more serviceable than others. The figures below indicate the range of
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strengths in lb. per square inch with, in brackets, the equivalent in meganewtons or N mm2:
Engineering brick s
Class A 10,000 (69)
Class B 7,000 (485)
Facing brick s
Flettons 3,000-4,500 (205—318)
Others 1,000—12,000 (7—83)
Common brick s
Flettons 3,000—4,500 (205—318)
London Stocks 750—1,500 or more (52—105)
Others 2,000—6,000 (14—414)
Alfred Searle, in the 1956 edition of his Modern brick making, points out that a brick in a wall has the tiny area of 025 square feet which is subject to vertical pressure from the brick s above it and that no less than 8,000 would be needed to crumble a
The properties of brick 15
brick in the lowest range of crushing strengths. These 8,000
brick s, one on top of the other, plus mortar, would reach a
height of 1,750 feet.
The architect planning tall buildings of load-bearing brick work. which must be economically costed, has of course to take account of crushing strengths. And there are structures for which the density and strength of blue engineering brick s are appropriate. But for ordinary small houses any modern building brick is much stronger than necessary for its job.
Even before firing, dried brick
s may have a crushing strength in excess of 350 lb. to the square inch and could be used in their green state for building a house in
There exist numerous old engineering works—bridges, retaining walls for railways—which theoretically demanded the strongest brick
s and did not get them. They were built with humble stocks and yet are still in good order after more than a hundred years. However, Victorian engineers calculated brick
work by rule of thumb and, tending to over-specify, got massive results—the early skyscrapers of
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The history of building in brick
appears to offer only one instance of disaster caused by too low a crushing strength—and that was largely a matter of builders’ negligence in that a great weight was allowed to rest on a small area of brick
work. During the afternoon of 17 January 1878, an oyster-seller in the Hay- market,
In the enquiry that followed it was established that, as a result of alterations to the two houses to produce shop fronts, much of the weight of both had been supported by a cast iron pillar resting on the stump of an old party wall. The brick s below and around the base of this pillar were crushed to dust.
How far this London accident of 1878 was a factor in making people sensitive about the compressive strength of brick
s is unknown, but the enquiry was fully reported in the Builder and it so happens that shortly afterwards activity in the testing of brick
s (and stones) became widespread. Later that year, in Germany, work began on setting up certain extra regional testing laboratories which had been called for by the Union of German Architects’ and Engineers’ Societies, and during the l880s conferences were held in Munich, Dresden, Berlin and Vienna to discuss the best ways of testing building materials. In
The United States Army was required in 1884 to test the brick
s of the New Pension House in
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1895 and 1897; piers built with different kinds of brick , in mortars made with lime and with cement, were tested after three months and six months.
Research into brick s and the machines to make them has been going on throughout the twentieth century in the laboratories of the bigger brick firms—London brick Company spends £100,000 a year on research—and in the national research stations to which the industry and government subscribe.
The British Ceramic Research Association has for years been subjecting samples of brick work to artificial rain, frost and wind; and it owns a rig of 900 tons with which the strength of walls is tried out by applying pressure from the side as well as from above. Tests inspired by London’s Ronan Point disaster of 1970, in which slabs high on a tower block came adrift when there was a gas explosion, have shown that properly bonded brick work will withstand explosions better than more modern building components. It was also found that only in the most contrived situation was it possible to achieve a gas-explosion pressure approaching 5 lb. per square inch. The British Ceramic Research Association also runs a clay-testing service. Members may send a sample and learn—before investing money in plant
—how far their raw material is suitable for brick
s. Since a clay report can be done on a sample of a pound or two, the service is well used by potential brick
makers overseas. It is an achievement of the Association that one of its experts on brick
s, Mr H.W.H. West, has written a useful book on brick
making for the developing countries, published by the United Nations in 1969. It is read in parts of the world where the need is to employ as many people as possible, rather than as few, and it thus describes procedures and equipment which are now old-fashioned in
A lot of work has been done on methods of putting holes in brick
s to make them lighter, to save clay and to keep out moisture. The Building Research Establishment at
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was especially active over this during the 1950s and drew interest with the invention of a double brick called the V, designed to span the whole width of a wall—it consisted of two perforated brick s joined together with webs in such a way that penetration by water is almost impossible. It has not been taken up commercially, partly on the grounds of expense and partly because of some discomfort in handling.
Hollow clay blocks, or structural clay tiles as they call them in
The change in the regulations did not cause a rush to make use of hollow clay blocks. Unlike in
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brick BC
The story of the brick begins with sun-dried mud brick s formed with hands alone. I have seen walls built with such brick s at least 10,000 years ago deep in excavated sections of ancient Jericho, which is believed to be the oldest town in the world. There are prized-out specimens clearly showing Neolithic hand marks.
These early brick s have the shape a person gives automatically to dough when breadmaking without a tin, and indeed they resemble long loaves of bread, flat underneath and rounded on top. Squeezing and consolidating, the makers sometimes left a bold pattern of thumb impressions; these had the incidental function of helping the brick s to key in with mud mortar.
The soil of
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city of clay and became dense and heavy on drying. Neolithic brick
s ring to the knock like concrete and have been shown by modern tests to have a crushing strength equal to half that of an ordinary fired brick
. They were vulnerable to water, as are all plain mud brick
s, and needed a plastering over with mud after wettings in the rainy season. The owner of a mud- brick
house in modern
Sun-dried brick s, requiring only labour to make, were so effective that kiln-fired brick s did not appear till the third millennium BC, long after the art of pottery had demonstrated the effect of a high temperature on clay. For thousands of years fired brick s were a luxury article for those able to command the use of scarce fuel. Even today, according to a recent United Nations survey, more of the world’s houses are built of unfired earth than of any other material.
In several countries, including
The earliest peoples on earth were nomads who sheltered in caves and temporary huts. Making brick
s came with settling down in one place and raising food from the land.
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more robust than shelters of twigs and daub was wanted, and the local soil, kneaded into convenient shapes, made the obvious building material. Neat mud brick
s were quicker to build with than lumps of stone that were irregular and in any case hard to find at
When the site of
The resultant mound is known in Arab countries as a tell. Jericho’s tell has been of special interest to archaeologists because of the famous story in the Old Testament concerning the capture of it by the Israelites in the fourteenth century BC and the fall of the town walls. The tell has been excavated several times in the past hundred years, but never more ably and scientifically than by teams directed by Dame Kathleen Kenyon in the 1950s.
Her conclusion that the stumps of mud- brick walls at the base of the tell are datable to the Pre-Pottery Neolithic period, to 8000 BC or even earlier, was based on Carbon 14 analysis of such organic material as wood and bones found in or near the walls. In her book Digging Up Jericho Dame Kathleen states that to form these walls—they are mainly 18 inches thick and some have brief stone footings—the majority of the brick s
are laid as stretchers, three to the width of the wall, but occasionally there are groups of headers running the full ,idth of the wall. The whole forms a structure which
it is still quite hard work to demolish, and it is a very
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Dimensions varied from house to house, but a common size was 10 inches by 3 wide and 3 deep, just small enough for the builder to hold with one hand; in this characteristic of being easily handled, valued by brick layers today, early Neolithic brick s are more similar to modern brick s than the great slabs which came to be made with the aid of moulds in the third millennium Bc—and which were usual in Roman times.
The archaeologists were able to study at
Living-room floors in this type of house had a finish of lime plaster laid concave at the junction with walls, a device used today in hospitals to prevent dust from accumulating in awkward corners. The floors emerged so hard and shiny that the archaeologists found they could effectively swill them down with pails of water, imagining as they did so the same action being performed 7,000 years ago by a Neolithic housewife. The cooking in these later houses of around 5000 BC seems to have been done in a central courtyard; for layers of ash were found separated by thin layers of clay, the find suggesting that when the courtyard became offensively grimy a new surface was laid on top.
This second Neolithic-Age Jericho came to an abrupt end, it has been realised, around 4500 BC. But a period of desertion was not followed by progress in the art of living. Indeed the next occupation exhibits a retrogression. The new people knew how to make vessels of pottery—an advance on hollowing out
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pieces of stone—but in all other respects they were more primitive than their predecessors. There is evidence that some settlers, rather than build, lived in pits dug out of the ruins. Those who made brick s made them small and bun-shaped. In Walls of Jericho Lady Wheeler, who worked with Dame Kathleen, commented that they seemed ‘idiotic’:
It is strange that such an inconveniently shaped brick
should have caught the imagination of those far-off peoples:
but evidently it did, because they were used by builders
farther away to the east in the Tigris and
improbable that the idea for such an idiotic brick should
have occurred spontaneously to two different peoples.
The smallness of bun brick s would have meant less failures through cracking in the hot sun, but most likely their appeal was simply that given two hands full of mud, the shape was the least trouble to form. Children could make them, and very likely did so.
The step forward in brick
making of using a box mould instead of merely the hands is dated to the Early Bronze Age, a period starting in the
The earliest walls of
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The worst threat to
Attacks on the walls by enemies occasionally took the form of lighting fires against them which, so far from causing a breach, served only to strengthen and harden them. At the foot of one stretch was found a layer of ash 3 feet deep, derived from a huge pile of brushwood. The mass of brick s, 17 feet thick at that point, had been burned red all through, a process helped (compare clamp firing at a brick yard) by interior fuel in the form of wooden ties. Building material was never deliberately fired, so far as is known, in the Early Bronze Age; though here, for anyone who had cared to take notice, was a demonstration of the effect of prolonged and intense heat on earth.
To hold the massive leafs together, here and there huge wooden ties were inserted.
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Largely because of erosion, remains of Late Bronze Age settlement have almost entirely disappeared, and unfortunately no trace at all remains of the walls of Jericho which fell down dramatically when menaced by the children of Israel in the fourteenth century; archaeology can add only conjecture to the vivid description in the Old Testament’s Book of Joshua. ‘One can visualise’, writes Dame Kathleen Kenyon,
the Children of Israel marching round the eight acres of the town and striking terror into the heart of the inhabitants, until all will to fight deserted them when on the seventh day the blast of the trumpets smote their ears. But as to what caused the walls to fall down flat, we have no factual evidence. We can guess that it was an earthquake, which the excavations have shown to have destroyed
a number of the earlier walls, but this is only conjecture. It would have been very natural for the Israelites to have regarded such a visitation as divine intervention on their behalf, as indeed it can be regarded.
Evidence of very early use of mud brick
s and blocks has been found in many other parts of the
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South America, in
Adobes were extensively used in the
peoples of the desert kingdoms of
either a mud plaster or a thin lime wash.
Since nothing has been discovered to link the ancient cultures of
During the 1960s archaeologists working at Catal Huyuk, southern
The period 2800—2300 BC produced in
From about 2000 BC till the fall of Babylon in the seventh century BC the normal mud brick s for important works resembled blocks of stone, 12 inches by 6 and 6 inches thick, or 14 inches square and only 4 inches thick. Some enormous struc
tures
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were put up, with walls up to 20 feet in width. A tower at Erech had its outer surface protected by thousands of pieces of pottery hammered into the mud while it was still slightly plastic; later on it became usual to encase certain buildings at least partially with burnt brick s.
The firing of brick
s has been carried out since the third millennium BC. Several specimens of this date from
The Israelites during their bondage were obliged to make enormous quantities of these heavy brick
s for the erection of such cities as Pithom and Rameses. Biblical accounts of their hardships are illustrated by tomb pictures which show them staggering under the weight of water pots, mounds of mud and yoke-loads of finished brick
s. Taskmasters, whip in hand, are plentifully represented. Nevertheless the Israelite captives seem to have been far from conscientious at times. The late Sir William Willocks reported in From the Garden of Eden to the Crossing of the
picked out of old ruins in the Delta scores of brick s which
contained nothing but straw daubed round with mud. These
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had undoubtedly been made by captives who were contemplating revolt. The taskmasters had furnished a sufficiency of straw for a certain tale of brick s, but the captives had hurriedly wasted it and delivered a totally inadequate number of brick s. . . . Those who acted in this way had begun to feel that they were not utterly helpless.
Deliberate wasting of straw accounts for the Pharaoh’s renowned instruction to the taskmasters of around 1490 BC:
Ye shall no more give the people straw to make brick . Let them go and gather it for themselves, and the tale of the brick s, which they did make heretofore, ye shall lay upon them.
The Pharaoh, Rameses II, was faced with industrial action. But this is not the first recorded dispute in the building trade, for around 2250 BC thousands of brick
makers and brick
layers went on strike at the site of the
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heaven, but when it had reached a certain height the workers in a mass left off what they were doing and scattered. They had become confused, it seems, by the number of different languages they were expected to understand and, according to chapter 11 of Genesis, the confusion was divinely inspired, signifying displeasure over the idea of raising a ladder to heaven. Shortly after the departure of the workers most of the tower fell down.
George Every has suggested in Christian Mythology, 1970, that the Genesis account serves as a parable on the subject of young people undertaking with enthusiasm tasks which are beyond their strength and powers of organisation. ‘As soon as this is discovered the groups dissolve in mutual misunderstanding and recrimination.’
In later Jewish legend, Mr Every points out, the building of the Tower of Babel was the first occasion for the sacrifice of human beings for the sake of a structure. If a man fell to his death it did not matter, but if a brick fell, it might take a year to replace. Women helping to make the brick s were not allowed to stop
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even to have a baby. When a baby was born, the mother had to strap it in a sheet to her back and go on working.
Where brick
s were burnt four or five thousand years ago, the job was done by one of two methods which are still current— in
The other method was to burn the brick
s in simple updraught kilns. These consisted of two chambers, one above for the brick
s and one below for the wood fuel. An early example, dating from about 2500 BC, has been excavated at Khafaje. Similar kilns were built by the Romans, and kilns following the same principle are still in use in
By the end of the third millennium BC some elaborate work was being done with the aid of burnt brick in the Sumerian cities of present-day Iraq; there is evidence of a palace built at Erech (c. 2400 BC) and a temple at Ur (c. 2300 Bc), while at Harappa and Mohenjo-Daro houses were built on platforms of burnt brick to raise them above flood level.
Most of the moulded brick s—that is, those not simply chopped into shape—were about 10 inches by 6 and 3 inches thick. The burnt brick s made centuries later by the Babylonians were commonly a little thicker and 12 to 18 inches square. By far the best example of building with these is the Ishtar Gate in Baby- ion constructed under Nebuchadnezzar II, 604—562 BC. It was faced with brick s embedded in bitumen; this was used hot, according to Herodotus, and came from Hit.
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Bituminous mixtures were also used in ancient
Nebuchadnezzar’s building work is given extra fascination by the fact that, unlike the Jerichoans, he lived in a civilisation
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buildings with mud walls, these being concealed beneath a most necessary covering of plaster and paint, tar, or weather tiles. Sometimes the occupants of old buildings are ignorant of what they are made of until they try to cut a new opening for a door or window.
A minor revival of the arts of building with earth took place during the brick shortages that followed the First and the Second World War. The architect Sir Clough Williams-Ellis gave encouragement during both periods and remains fascinated by the idea of getting houses to rise up literally out of the ground. He has probably written the last word on the subject, so far as its history goes, in his book Building in Cob, Pisé and Stabilised Earth, 1947.
Building with cob was the slowest and most laborious method, since each layer of wet material, laid on with spades, had to be allowed time to dry. Pisé de terre is the name for earth rammed down nearly dry between shutters: some experimental pisé cottages built at Amesbury in the 1940s remain in good order
—another was added to the group in 1959. Stabilised earth consists of top soil and cement formed into blocks. Clay lumps resemble ordinary brick s in their green state—they are laid with a soft clay mortar. Sir dough commented as follows on the matter of strength:
All forms of earth construction have proved themselves adequate to support the loads of the normal twostorey house—about 1+ tons per foot run—provided walls of a generous thickness, usually about 18 ins, to 2 ft. are used.
It is claimed that compressive strengths of 1000 lb. per square inch and more can be achieved with cement stabilised earths, and while these figures may be somewhat extravagant, depending on careful control in the soil mix and very thorough compaction, it should nevertheless be possible to exceed 400 lb. per square inch, at which strength it would be reasonable to use the material in cavity
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construction with leaves 4 ins, in thickness, provided the usual number of wall ties were included. This would
of course apply only to two-storey houses with joisted
floors and with evenly distributed loading.
That, however, was written in 1947. Even experimental building with earth was virtually brought to an end in
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Roman brick
Mud brick
s were being used in
Burnt as well as sun-dried mud brick
s were being made in and around
Gravelly, pebbly and sandy clay are unfit for the purpose; for if made of either of these two sorts of earth, the
brick s are not only too ponderous, but walls built of them, when exposed to the rain, moulder away, and the straw
with which they are mixed will not sufficiently bind the
earth together because of its rough quality. They should be made of earth of a red or white chalky, or of a strong sandy, nature. These sorts of earth are ductile and cohesive, and not being heavy, the brick s made of them are more easily handled.
The proper seasons for brick making are the spring and autumn, because then the brick s dry more equably.
When plastering is laid and sets hard on brick s which are
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not perfectly dry, the brick s, which will naturally shrink, and consequently occupy a less space than the plastering, will thus leave the latter to stand by itself . . . it soon
breaks to pieces, and in its failure sometimes involves that of the wall. It is not, therefore, without reason that the
inhabitants of
buildings which are not at least five years old and
also approved by a magistrate.
Mud brick s came in three sizes apparently: the didoron, a foot long and half a foot wide; the pentadoron, five palms of the hand each way; the tetradoron, four palms each way. The pentadoron was for public buildings and the other two for private buildings. Each sort had a half- brick made to suit it.
The Romans’ first use for fired building material was to make tiles to waterproof roofs. But the builders found the tiles, and broken pieces of them, so valuable for strengthening vulnerable parts of walls that when, in the first century AD, burnt building brick s were demanded, these were made tile-like to match existing work—and also because thin brick s took less fuel to fire. The word ‘tegulae’ meaning tiles served also for brick s. The brick earth was sometimes trodden or banged out like pastry and then made into brick s by cutting.
usual size was a foot or so square and 1- inches thick, but there were many others: small brick
s to be laid on edge in floors (as in the Forum at
columns and octagonals for certain small columns. Walls were generally composed only partly of brick s, having them as a protective facing to a core of concrete made with lime and earth
with lime and volcanic ash.* In Rome itself there was a liking for pyramid-shaped brick s. The apex of each was embedded in the concrete, though occasionally the units would be reversed to produce a strongly textured effect. Since the concrete hardened slowly, the outward thrust of it during
The Romans’ discovery that volcanic ash near
led to the modern term pozzolanic.
37
not perfectly dry, the brick s, which will naturally shrink, and consequently occupy a less space than the plastering, will thus leave the latter to stand by itself . . . it soon
breaks to pieces, and in its failure sometimes involves that of the wall. It is not, therefore, without reason that the
inhabitants of
buildings which are not at least five years old and
also approved by a magistrate.
Mud brick s came in three sizes apparently: the didoron, a foot long and half a foot wide; the pentadoron, five palms of the hand each way; the tetradoron, four palms each way. The pentadoron was for public buildings and the other two for private buildings. Each sort had a half- brick made to suit it.
The Romans’ first use for fired building material was to make tiles to waterproof roofs. But the builders found the tiles, and broken pieces of them, so valuable for strengthening vulnerable parts of walls that when, in the first century AD, burnt building brick s were demanded, these were made tile-like to match existing work—and also because thin brick s took less fuel to fire. The word ‘tegulae’ meaning tiles served also for brick s. The brick earth was sometimes trodden or banged out like pastry and then made into brick s by cutting.
usual size was a foot or so square and 1- inches thick, but there were many others: small brick
s to be laid on edge in floors (as in the Forum at
The Romans’ discovery that volcanic ash near
led to the modern term pozzolanic.
38
shaped, the soft wet brick s were left on a bed of sand to stiffen enough to be stacked in the kiln. During this period they might acquire unofficial marks: foot or paw impressions and lighthearted drawings of faces. A Roman brick in the Guildhall Museum, London is inscribed, apparently with a twig, AVSTALIS DIBVS XIII VAGATVR SIB COTIDIM, which means ‘Austalis has been going off by himself every day for a fortnight’—thirteen days equals a fortnight in colloquial Latin. A worker seemingly wished to draw attention to the absences of one of his mates.
Roman brick
kilns had several flues beneath the oven floor and were similar to kilns that had been in use two thousand years previously—and to some kilns of the Middle East today. In 1932 Dr Norman Davey excavated a Roman kiln at
The structure, composed of pieces of brick and tile bonded with clay, was built below the natural level of the
39
ground. In this way the structure was solid and better able to withstand the stresses set up in it by the great heat, and the heat losses were greatly reduced. As the level of the oven floor was approximately the same as that of the ground, the stacking of brick s in the oven was easy. The kiln, as was usual, was built on the windward slope of the hill and the fire tunnel was lengthened to increase the draught... the products to be fired would have been surrounded and covered by pieces of burnt brick and tile smeared with clay to protect them from the weather and to prevent the heat escaping too quickly.
Although nearly all the brick
s made in
40
into the walls, among the classical features, to produce the sort of polychrome effects of yellow, red and brown which stamp many houses in Britain as late Victorian—these also, of course, were put up during the final years of a great empire. Examples of such Roman brick
buildings still exist in
The craft of brick
making appears to have ceased in
At Holy Trinity church, Coichester, the Saxon tower is built of brick
s taken from the Roman city of
41
ruins of which lay to hand. Verulamium, another city, was systematically broken up late in the eleventh century (and again early in the twelfth) to get materials for what is now St Albans cathedral: the west front there has a profusion of tile-like brick
s in conjunction with stone and is regarded as one of the best examples in
Summing up, it can be said that though there are only a few places in Britain where Roman brick
s can be seen doing their job in the buildings for which they were made, they still help to support plenty of buildings raised in later and less secure ages. The use of brick
s for strengthening purposes, as demonstrated by the Romans, became part of the British building tradition. It is especially noticeable in chalk districts; the walls of flint which are common on the downs of southern
43
the great brick
occurs in northern
The eastern counties of
The advance of brick
work in eastern England, with the spread of such familiar features as the Dutch gable, was encouraged by merchants and sea captains who had to visit the towns abroad where brick
making flourished and impressive buildings struck the eye. English brick
could almost be called a by-product of dealings with the Hanseatic League: this was a powerful combination, formed in 1241, of trading centres in the Low Countries and north
4- by 2 for Holy Trinity church, 1315—20—this building was so artfully stuccoed in the eighteenth century that in 1756 a visiting antiquary supposed it not to contain a single brick .
45
The first dwelling house built with more brick
than other materials is Little Wenham Hall,
Mr Harley, who is president of the British brick Society, puts forward the theory that the measurement which has changed least is the half-girth. The breadth plus the thickness, he points out, are the important dimensions when it comes to picking up a brick ; and he takes into account the smaller size of the mediaeval hand shown by suits of armour.
In the fifteenth century the main use of brick
that developed was in the building of schools and colleges (Eton;
Herstmonceux, a fairy tale castle in peach-coloured brick
, c. 1440, is certainly French in feeling: Sir Roger Fiennes, its creator, was at
47
are an early example of a type of flat ornament in brick work, used in France, which was to become common over much of England; the skill with which the patterns were worked in Tudor times—as at Farnham Castle, Surrey—may be the more marked if these are compared with modern versions. Caister Castle in Norfolk, whose brick s seem to have come from a site by the River Bure still called brick Pits, was built around 1430 by Sir John Fastoif who had seen long service in France and, although Caister is now in ruins, its circular tower and corbelling show French influence.
But there were of course other Continental influences during a period when places like
In the Tudor period (1485—1603), brick
became so well thought of that the rich were glad to have their houses built with it exclusively, even sometimes in parts of the country offering adequate supplies of stone. When people saw that brick
was good enough for the king himself, its social acceptance as an alternative to stone was complete. A dark but mellow red was preferred; today the very word Tudor suggests the brick
of that colour at St James’s Palace and the older parts of
If Henry VIII’S reign (1509—47) was the first great age of brick , it
48
was also an age of remarkable—and pleasantly absurd—chimney building.
By the beginning of the sixteenth century most house-owners at least aspired to chimneys, and brick
was widely called for as the best material for making them. It was also, since it readily took special shapes before firing, a material which allowed the brick
maker and brick
layer to outdo the stone mason in meeting a demand for show. Many stone houses were fitted from the start with brick
chimneys. The brick
s had to be bright red to make sure that the work stood out. Mr Fletcher reports that at Collyweston,
vij lb. of red ocker with 1 oz. of the offales of the glovers lether, vijd. Item to John Bradley wiff for xiiij gallons
of small ale for the said cheney of bryk, vjd.
The affluent appearance of the chimney stacks of Tudor resi
* brick
s had formerly been called walltyles. The Norman-French word briche began to be used in the late fourteenth century and was spelt brik, brike, brick
e or bryk. A fourteenth- century dungeon at
50
dences, visible from afar, influenced those concerned with the building of lesser dwellings. Yoeman farmers added ornamental brick
chimneys to their oak-framed houses and those who were building afresh knew that brick
s were an urgent requirement, for the stack would go up first and have the rest of the house built round it. A surprising number of farmers, perhaps chimney snobs, contrived to have the upper part of their stacks made in the octagonal, hexagonal or spiral form of high fashion; work of this kind can often be seen where old half-timber buildings are grouped together. Famous examples of virtuosity in chimney building include those at Gainsborough Old Hall in
The use of brick
for all purposes spread in the second half of the sixteenth century to several districts in which before it had been unknown. By 1574, according to the Victoria County History,
Long before the Great Fire, the advantages of brick
were being appreciated in
* Talk of the so-called Elizabethan Statute brick has arisen through Nathaniel Lloyd
supposing that this document, giving the brick
Size 9 inches by 4+ by 2+, referred to a statute where in fact it merely confirmed
52
over the manufacture of brick
s and tiles for the City of
Most people having some acquaintance with
53
Early brick making practice
Pre-industrial brick
making in
Throughout the early centuries of brick making, the work—it was work for the summer months only—was done by builders and their labourers, by farmers and theirs and by itinerant brick makers who were called in to produce the materials for a particular building. An agreement of 1644 relating to Syon House, Middlesex—M.W. Barley describes it in his English Farmhouse—gives an idea of what happened. John Hawkes of Hounslow was to have £5 towards digging the earth, £3 for each week when it came to working, £5 15s. at the end of making half a million brick s and, finally, 6s. 8d., for each 10,000 ‘well and sufficiently burnt and delivered out of the kiln’. As late as 1833 J.C. Loudon, in his Encyclopaedia of Cottage, Farm and Villa Architecture, advises farmers on how to make their own brick s; and many an isolated brick barn, by no means ancient, has near it a patch of irregular ground (there may be a small pond) which indicates where once there was a miniature brick field.
Commercial yards equipped with permanent kilns existed none the less from the fourteenth century. One of the first was at Beverley in
54
market for brick s not needed on the estate: the Ashburnham Estate brick yard, founded in mediaeval times, became so well thought of that its products, fired with wood, were still being sold to the public in 1968.
Much of the charm of the earliest English brick s derives from their numerous imperfections. Carefree puddling and squeezing of the raw material, followed by fierce firing, produced plenty of misshapen specimens, a well-pitted texture and a variety of soft colours. The use of esturine clay may show itself in water- formed, wavy lines.
The brick
s of the
55
out on straw. The more general procedure, though, was to form brick s in moulds and then to arrange them on straw to dry. When a mediaeval brick is prized from its fellows in a wall an impression of straw, sharply etched, is often seen; and there may be lines showing where another brick had rested during drying. Examining these marks, and studying the documents of such a brick yard as Hull’s, has shown students of brick that the method of making hand-moulded brick s has probably changed little since mediaeval times. Much study in this field has been done by the geologists Ronald and Patricia Firman, who reported results in 1967 in the Mercian Geologist, journal of the East Midlands Geological Society.
brick earth was dug in the autumn, they confirm, and piled in heaps for the action of the weather, especially frosts, to break it down to some extent. In the spring it was tempered—that is, trodden or turned with spades to produce an even plastic consistency. The moulder, working at a table, sanded or wetted his wooden mould and threw into it with some force a lump of clay. He sliced the surplus from the top of the mould with a stick known as a strike or with a cutting wire on a bow.
The moulded brick s were carried—sometimes in the mould and sometimes between two small boards called pallets—to the drying ground and laid out in a herringbone pattern. When the first row was partly dry, a second was laid across it and when that was ready, a third, until a height of ten rows had been reached. This pile of drying brick s was known as a hack. For the brick s to be dry enough to fire might take a month, during which time straw covers protected the hack from rain and excessive sun.
Burning seems to have been mainly done in kilns of the simple up-draught kind. Otherwise, brick s were burnt in clamps (or heaps), but as the word clamp was often used of permanent kilns, there is uncertainty about the prevalence of the method. It is known, though, that kilns were made from unfired brick s if fired ones were not available and that green brick s were often
56
stacked inside them in the way they were stacked in the hack. There are a few brick
yards in
brick s may be regarded, geologically, as heat formed sedimentary rocks. Having so considered samples of mediaeval brick , Ronald and Patricia Firman were convinced from the evidence of plasticity, of fossils and other inclusions that only superficial clays were used; that no mediaeval brick s were made from the older carboniferous shales, Keuper marl and Jurassic clays, which are the raw material for about 80 per cent of modern
57
brick
s. This accounts, they say, for the obvious difference in appearance of mediaeval and modern brick
buildings—and the reason for a less marked difference in
Nearly all mediaeval brick s were made of brick earth taken straight from the ground with nothing added. Exceptions include the brick s at Little Coggeshall. These have been found to contain a high proportion of coarse sand, all its grains about a millimetre in diameter, which is evenly distributed throughout a matrix of very fine particles. The Firmans concluded that the
lack of intermediate-sized grains suggests that this is an artificial mixture. If this deduction is correct, then as
early as the 12th century some brick makers were aware of the value of adding sand to plastic clay to reduce the
shrinkage on drying and burning. The technique was already known and used by potters in
Early brick
s which are pale pink or yellow, as at
Red was the colour aspired to by nearly everyone planning to erect a brick house or add a brick chimney to a timber house. When the redness was thought inadequate for a certain task, it might even be increased artificially. Records of a manor house at Collyweston, Northamptonshire, show that about 1505 the colour of brick s for chimneys was improved by a mixture of ‘offalles’ from glove leather and ale.
A picture of mediaeval brick
making appears in a Netherlands Bible of 1425: it purports to show the Jews at work in
58
nus Schopperus published in
boards nail’d about nine inches high to lay sand in and in the middle we fasten with nails a piece of board, which we call a stock; this stock is about half an inch thick and just big enough for the mould to slip down upon. Then we have a mould made of beech, because the earth will slip easiest from it . . . we also have upon the table before the mould a little trough, that will hold about three or four quarts of water which we put in, and in it a strike to run over the mould to make the brick s smooth. . . . When we are thus prepared with utensils, then one man strews
59
nus Schopperus published in
boards nail’d about nine inches high to lay sand in
and in the middle we fasten with nails a piece of board, which we call a stock; this stock is about half an inch
thick and just big enough for the mould to slip down upon. Then we have a mould made of beech, because the earth
will slip easiest from it . . . we also have upon the table
before the mould a little trough, that will hold about three or four quarts of water which we put in, and in it a strike
to run over the mould to make the brick s smooth. . . . When we are thus prepared with utensils, then one man strews
59
sand on the table (as maids do meal when they mould bread) and moulds the earth upon it, then rubbing the stock and inside of the mould with sand, with the earth he forms a brick , strikes it, and pays it upon a pallat; then comes a little boy about twelve or sixteen years old and takes away three of these brick s and pailats and lays them upon a hackstead, a raised place.
There follows a description of how the boy stacks the green brick s to dry, arranging them on edge in a herringbone pattern, and of how he covers the piles with straw; it took between three weeks and a month for the brick s to become dry and hard. Houghton remarks that a moulder helped by a temperer and by
boy to carry off the brick s, would make 2,000 ‘in a summer’s day, viz., about fourteen to fifteen hours’, though an extraordinary man could make 3,000. Without assistance, his day’s output would be about a thousand. Alone or helped, his pay was 4s. for 1,000 brick s, a rate which remained roughly constant until the early twentieth century when it dropped by over a shilling. Houghton describes the firing:
Our brick s being thus prepared, the next matter is to burn them, which is after this manner: When we begin a new brick ground, for want of burnt brick s we are fors’t to build a kiln with raw brick s, which the heat of the fire by degrees burns, and this will last three or four year; but afterwards we make it with burnt brick s and we choose for it a dry ground, or make it so by making dreyns round it. This kiln we build two brick s and a half thick, sixteen brick s long from inside to inside and about fourteen or fifteen feet high; at the bottom we make two arches three foot high. .
After a rather complicated account of stacking the brick s in the kiln, Houghton writes of lighting a small fire in each arch to drive off the ‘water-smoak’ and of then increasing the size of the fires until the brick s become red hot throughout the kiln.
60
The firing would take no more than three days, including the cooling down.
Then we sell the brick s as soon as we can for as much money as we can get, but usually about thirteen or fourteen shillings per thousand. The prices for making and burning is seven shillings the thousand, the wood three shillings the thousand.
By the second half of the seventeenth century the usual kiln was of the intermittent type known as Scotch. It was a large cham}jer, open at the top, with a series of fire holes along each side opposite one another. The dried brick s were stacked inside in such a way that the hot gases could surge up between them. A layer of old burnt brick s was then spread over the top, the ends of the kiln were brick ed up and roughly plastered over with clay, and fires were lit in the fire holes. When the burning process was completed, the kiln was allowed to cool and the brick s taken out. Under this method of manufacture,
the shade of the brick s varied a great deal, those nearest the fires being the darkest. These harder-burnt, darker brick s had also shrunk more. On being taken from the kiln, the brick s were roughly sorted to give the purchaser consistent lots.
But regular kilns were put up only in brick
yards with some degree of permanence, and firing in open clamps was probably more usual. This kiln-less method was favoured by the itinerant brick
makers, whose equipment on coming to a site need be little more than spades and a wooden mould; they reckoned to find their water and fuel locally. brick
s were now considered so necessary in many parts of
61
A labour-saving piece of equipment which emerged at the end of the seventeenth century was the pugmill for blending the clays (or pug). The pugmill was a kind of barrel containing a vertical shaft with projecting blades. There was a long beam attached to this shaft to which a horse could be harnessed to give the motive power by walking round and round. The raw materials were fed in at the top of the mill and came out at the bottom as a reasonably smooth paste. A little girl’s experience with a pugmill near Ramsey late in the nineteenth century appears in Sybil Marshall’s Fenlanci Chronicle, 1967:
When I was very small, my mother worked in the brick yards. I had a small swing fixed up for me on the beam opposite the horse, and round and round I used to go all day. If the horse dropped any dung, it had to be cleared away immediately, to keep the path from becoming greasy and in bad condition. So, as I travelled round, I kept a diligent watch for this, and was delighted when I could call out, ‘Tom, old Jack’s messing again.’
62
brick work of the seventeenth
and eighteenth centuries
The Great Fire of London in 1666 was the more devastating for
the fact that the majority of houses were still wooden. The
City authorities insisted afterwards that new work should not
be done with anything so combustible as wood and strongly
recommended brick , described in the Act for the Rebuilding of
the City of
walls were to be built of brick , or stone, but also all ornamental
projections.
A huge demand for brick layers had the effect of undermining the power of the Tylers’ and brick layers’ Company: the number of craftsmen permitted to work as freemen for the Company (and for other City Guilds) was inadequate for the emergency, and workmen were liberated by Act of Parliament from the obligation to join a guild before practising their trade. The Tylers’ and brick layers’ Company never regained its authority, though a recoup of finances in the nineteenth century