The Ultimate Guide to Brick Making: Processes, Types, and Materials

Bricks are one of the oldest and most enduring building materials in human history. Their qualities of durability, fire resistance, and aesthetic appeal have made them a fundamental choice in construction across diverse cultures . Today, the brick-making industry produces over two gigatonnes of ceramic products globally each year, with a surprisingly wide range of manufacturing techniques .

From the historic hand-thrown clay brick to the high-speed extruded bricks used in modern construction, this comprehensive guide covers everything you need to know about brick making—including the raw materials, the manufacturing process, different brick types, and the latest innovations in sustainable production.

What Are Bricks Made Of?

A “normal” brick is primarily composed of clay, which is the essential raw material. The typical composition of a clay brick includes :

• 50% Sand – Provides structure and reduces shrinkage
• 30% Clay – The binding agent that provides plasticity
• 5% Lime – Helps with binding and firing
• ≤7% Iron Oxide – Influences the color (higher iron content creates a more rustic red brick)
• <1% Magnesia – Minor component

The color of the brick is determined by the mineral content of the clay and the firing conditions. For example:

• White bricks have a higher lime content
• Rustic red bricks have a higher level of iron oxide
• Blue/dark bricks are fired at high temperatures with low oxygen levels 

The ideal clay for brick making should be:

• Easily available
• Plastic when mixed with a small amount of water
• Capable of developing strength upon drying
• Able to develop hard, durable strength when fired 

Suitable soils generally contain 25% to 50% clay and silt and 50% to 75% coarser material .

The 5-Step Brick-Making Process

The production of clay bricks follows a standardized sequence of five main steps :

Step 1: Winning (Clay Extraction)

The process begins with extracting clay from the ground. In small operations, this can be done by hand labor removing overburden. In larger operations, a combination of mechanical devices such as graders and draglines are used . The clay is typically mined through open-pit or strip mining .

Step 2: Preparation of the Clay

Once extracted, the raw clay must be prepared :

1. Primary Preparation: Crushing the raw material, removing stones (impurities like roots or pebbles), and blending different clays if desired .
2. Secondary Preparation: Grinding the crushed lumps to the desired fineness .
3. Soaking: The ground clay is placed in a soaking pit where it is mixed with water to obtain the correct consistency required for molding .

The complexity of the preparation process depends on the quality of the clay. If the clay is relatively free of impurities, it can be formed, dried, and fired directly .

Step 3: Molding (Shaping)

There are three primary techniques for shaping fired-clay bricks :

1. The Extruded (Wire-Cut) Process

This is the most popular method, accounting for approximately 65% of production in the UK. The clay is mixed with approximately 13–18% water to a stiff plastic consistency and forced through a die. Taut wires then cut this continuous “sausage” of clay into individual bricks . The extrusion method can produce approximately 20,000 bricks per hour .

Distinctive features:

• The brick has perforations or core holes running through it 
• These holes reduce weight and assist in even drying and firing 
• Produces hard, dense bricks with consistent size and shape 
• Bricks can be textured (dragfaced, rolled texture, sandfaced, or glazed) 

2. The Soft-Mud Process

The clay is thrown into moulds either by hand or by machine. This process uses clay with a higher water content (25–30%) . Bricks made by this process are known as “stock bricks” .

How it’s done: A lump of clay is rolled into a wedge shape and coated in sand before being thrown into a sanded mould to prevent sticking . With the help of assistants, a skilled brick moulder can make 3,500–5,000 bricks a day .

Distinctive features:

• More traditional or reclaimed appearance with a softer, warmer aesthetic 
• Bricks are irregular in shape with soft arises 
• Often have a “frog” indentation rather than perforations 

3. The Semi-Dry Pressed Process

This method uses hydraulic presses to push semi-dry clay (approximately 10% moisture content) into steel moulds . It is reserved for specific types of bricks such as Fletton bricks in the UK .

Step 4: Drying

After shaping, the “green” bricks are dried to remove excess moisture. This step is critical—if water is not removed, the bricks could expand and be damaged during the firing process .

Drying process:

• Bricks are left to dry for approximately 2–3 days in the place where they were made 
• They are then stacked in a herringbone pattern to dry in the air 
• After about two weeks of drying, the bricks are ready to be fired 
• During drying, the bricks must be protected from rain 

A brick is sufficiently dried when, upon being broken in half, it shows no color differential throughout the section area .

Step 5: Firing (Burning)

Firing is the crucial step that transforms clay bricks into stable, durable, weather-resistant units. Firing removes any remaining moisture and, as the temperature increases, renders the brick stable and able to resist weathering . The firing and subsequent cooling process typically takes between 40 and 150 hours, depending on the clay type and kiln used .

Firing temperatures:

• Temperatures range from 900°C to 1150°C (1,652°F to 2,102°F) 
• The highest temperature reached can be up to 1,800°F (982°C) 
• The firing process is gradual—the temperature is raised slowly to prevent bricks from exploding from trapped steam 

Types of Kilns :

Three Main Types of Bricks

Bricks are generally classified into three main categories based on their properties and applications :

1. Facing Bricks

Used to create the facade of a building—the external wall that faces outward. The color, texture, and overall aesthetic are significant factors .

• Primary purpose: Appearance and weather resistance 
• Strengths: Wide range of 12–120 MPa (1.7–17 ksi) 
• Application: Visible exterior walls
• Manufacturing: Extruded or soft-mud process

2. Engineering Bricks

Used for their physical characteristics, not their appearance . They are classified by compressive strength and water absorption .

Applications:

• Groundworks and retaining walls
• Manholes and sewers
• Damp-proof courses
• Structural load-bearing components 

3. Common Bricks

Despite their name, they are actually the least common type in many countries .

• Primary purpose: General purpose
• Quality: Lower compressive strengths than facing or engineering bricks; less attention paid to consistent appearance 
• Limitations: Should not be used below ground level; generally for internal brickwork only 

Sustainable Innovations and Future Trends

The brick industry is increasingly focused on sustainability and reducing its environmental footprint. The production of ceramics produces over 400 million tonnes of CO₂ per year from energy use and the calcination of carbonates in the clay . To address this, manufacturers are exploring several innovations:

1. Recycled Waste Materials in Brick Making

For many years, recycled waste materials from other industries have been utilized in the manufacture of clay bricks :

• Pulverized fuel ash (PFA)
• Blast furnace slag
• Coke breeze and coal slurry
• Ground glass (cullet)
• Sewage sludge
• Paper ash, bone ash, and sawdust

These account for around 10% of raw materials used and serve multiple purposes:

• Improving frost resistance or color
• Acting as a source of fuel, reducing external energy requirements 
• Ground glass acts as a fluxing agent, reducing firing temperatures and times, with energy savings of up to 20% possible 

2. Unfired Clay Bricks (Low Embodied Energy)

Unfired bricks (also known as adobe blocks or rammed earth blocks) are not kiln-fired, resulting in very low embodied energy .

Key data:

• Embodied energy: 146 kWh/tonne
• Embodied carbon: 44.6 kg CO₂/tonne
• This is approximately 14% of the value for comparable fired-clay brickwork 

Limitations: Usually used for internal non-load-bearing walls .

3. Energy Efficiency Improvements

Modern industrial brick production uses natural gas and fuel oil as the main fuels, with specific energy consumption of 1.4 to 2.4 GJ/t of product . There is a continued push toward:

• Increasing the use of combustible waste materials as a fuel source
• Improving kiln efficiency
• Reducing CO₂ emissions from clay calcination 

Frequently Asked Questions (FAQ)

Q1: How long does it take to make a brick?

From clay extraction to finished product, the complete brick-making cycle typically takes several weeks for handmade bricks, including drying and firing. Industrial processes can be much faster, with extrusion producing up to 20,000 bricks per hour, though the firing cycle still takes 2–3 days .

Q2: What is the difference between extruded and handmade bricks?

Extruded bricks are machine-made and have perforations, consistent size, and sharper edges. Handmade bricks are irregular in shape with softer, more interesting surfaces—but both can be equally high quality .

Q3: Can bricks be made from any clay?

No. The ideal soil for brickmaking must contain 25% to 50% clay and silt and have good plasticity when moistened. Simple tests, such as the cylinder test, can identify suitable clay .

Q4: Are bricks environmentally friendly?

Traditional fired bricks have a significant carbon footprint. However, innovations like using recycled waste materials in the clay mix, and unfired (air-dried) bricks, have greatly reduced their environmental impact .

Q5: What makes engineering bricks different?

Engineering bricks have very high compressive strength (over 75 N/mm²) and very low water absorption (under 7%). They are used for structural strength and water resistance, not appearance .

Q6: Can bricks be made by hand today?

Yes. Handmade soft-mud bricks are still produced today, often for use in restoration projects or to achieve a specific traditional aesthetic .

Q7: Why do some bricks have holes?

In extruded bricks, the perforations allow heat to penetrate the brick evenly during firing, significantly reducing the risk of warping or cracking . They also make the bricks lighter and easier for bricklayers to handle . The holes do not negatively affect insulation or fire resistance .

Q8: What color will my bricks be?

The final color depends on the mineral content of the clay and the firing conditions. Higher iron content creates reddish colors; higher lime content produces white bricks. Firing at high temperatures with low oxygen creates dark blue or brown bricks .

Q9: How long do bricks last?

Bricks are incredibly durable. Many historic brick structures have survived for centuries. With proper manufacturing and installation, modern bricks can last well over 100 years .

Q10: Is the brick-making process the same worldwide?

The fundamental process is similar everywhere, but manufacturing methods range from sophisticated, high-volume industrial facilities to simple, labor-intensive cottage production still common in many developing countries .

Conclusion

Brick making is one of the oldest manufacturing processes in the world, yet it continues to evolve with modern technology and sustainability demands. The five key steps—winning, preparation, molding, drying, and firing—remain the foundation of the industry, but innovations in materials and kiln technology are making brick production cleaner and more efficient than ever.