Everything you wanted to know about bricks… but were afraid to ask.
One of the earliest mentions of bricks appears in the Bible: “And they made their lives bitter with hard bondage, in mortar and brick…” (Exodusi, 14). The phrase “you’re a brick”, meaning solid and dependable, originated with King Lycurgus of Sparta, who pointed to his soldiers and said: “There are Sparta’s walls and every man is a brick, “according to the Encyclopaedia of Word and Phrase Origins, by Robert Hendrickson.
“The Hanging Gardens of Babylon, one of the Seven Wonders of the World; the Great Wall of China, the largest man-made object on the planet; the Hagia Sophia, one of the most beautiful churches yet built; the great medieval castle of Malbork,, Poland, which is the size of a small town; the 2000 temples in Pagan in Burma, which have survived intact for 900 years; the engineering achievement of Brunellschi’s dome in Florence; the structure of the Taj Mahal in India; the 1,200 miles of sewers that the Victorians built under London; the unforgettable profile of the Chrysler building in New York City – all these have one thing in common; they were build out of brick, “writes James Campbell in his book Brick a World History.
Often overlooked in favour of more fashionable architectural materials, the brick has been with us a long time.
Built to last
“Roman bricks that were already 1,000 years old were taken from the ruins of nearby Verulamium in the 12th century and re-used for the construction of St Albans Cathedral where they are still in good condition in the 21st,” says Michael Hammett, of the British Brick Society.
Simple to makes
The mud brick, or adobe, to give it its proper name, was invented between 10,000 BC and 8,000 BC. Next came the moulded brick and then, in about 3,500 BC, the burnt brick. Burnt bricks have the resilience of stone but can also be shaped and fired with glazes to produce a variety of bright colours. The Ziggurat at Ur, in Iraq, is an early example of monumental brickwork using sun-dried brick.
All fired up
Centuries of development in the kiln have led to today’s manufacturing processes, although there are still craftspeople making bricks by hand and firing in more traditional clamps or kilns. Up until the Second World War, most bricks were used within 30 miles of where they were made.
Colour me purple
The colour of the brick is affected by the mineral content of the original clay, the temperature of the firing and the atmosphere in the kiln. Pink bricks burn to hues of red, with higher-burn temperatures leading to dark reds, purples, browns, the greys.
A variety show
There are three basic production techniques: hand making, also known as the process; extrusion, where the clay is squeezed out like toothpaste from a tube, and then cut by wire, so they are also known as “wire cut”, and pressing, where the clay is squashed into a steel mould. Hand-made bricks have a high textured, creased face. The wire cut is smoother and more precise, and the press produces a sharp angled brick. Bricks are classed as “common” when there is no guarantee of a consistent face; “facing”, which has an attractive appearance: and “engineering” for load-bearing and water resistance. Bricks are often marked with the manufacturer’s name. The indentation at the centre of a stock brick is known as a “frog”. As well as helping to press the clay into the sides of the mould, it helps the brick to dry before firing.
Size isn’t everything
Since the 1960s the most common brick size in the UK is 102mm wide, 215mm long and 65mm deep. However, traditionally bricks in the North of England were 73mm high and in the South 68mm high.
The numbers game
In the UK about 30 manufacturers operating about 65 brick yards make around 900 types of brick. The brick industry sells between 1.5 billion and 2.5 billion bricks a year.
The name’s bond
When bricks are laid they form patterns between courses, called bonding patterns. The most common, typical of a cavity wall, is a called stretcher bond.
The thickness, colour and finish of the mortar joints, normally 10mm, or 18 per cent of the finished wall, also have an impact on the final look. Adding lime to the mortar makes it white, adding sand turn it yellow.
Andrew Halstead-Smith of Ibstock, a brick manufacturer, says: “Bricks are environmentally friendly, containing on average 10 per cent recycled material. They can also be recycled afterwards.”