An ancient invention, kilns have been used by humanity for thousands of years for drying, baking, and burning various objects. Today, they are used not only for pottery and the production of fine china, but also to create firewood, briquettes, fire starters, and other wood heating fuels that burn much more cleanly and efficiently than air-dried options.

Being the UK's most trusted and best reviewed wood fuel supplier, Lekto Woodfuels is a world-class expert in the kiln-drying of firewood, kindling, and night briquettes. This is why we will focus on this aspect of kiln usage, leaving the other aspects to experts in those particular fields.

Within the wood heating fuel context, a kiln is a ventilated, high-temperature chamber used for drying wood fuels. This process, although more expensive, enables the production of extra-low-moisture firewood and briquettes. And why is this important? Because low moisture wood fuels are easier for you to light and burn much more cleanly and efficiently than less dry options.

This is better for your wallet, the planet, and the health of you and your loved ones:

• It's better for your wallet because far less heat energy is wasted on evaporating water.
• It's better for your health because the less water evaporates, the less smoke is generated during each burn cycle (which you inevitably end up breathing in). 
• And it's better for the planet, because the less smoke is generated, the fewer PM2.5 and PM10 emissions are released into the atmosphere.

In this expert-written guide, we’ll explain what a kiln is, how kiln drying works for firewood and briquettes, and why it’s a far better and more efficient option than the cheaper wet wood and air-seasoned wood options.

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What Are Kilns and How Do They Work?

Despite being associated with fairly advanced technology, kilns are actually one of humanity’s oldest technologies. The first kilns were used to make clay pots. The technology was then refined by the Chinese to produce fine porcelain. Today, kilns are used on an industrial scale for the production of ceramics, cement, and, yes, the creation of renewable firewood and wood briquette energy.

The History of Kilns

The rich history of the humble kiln stretches back millennia. According to archeological data, even the earliest modern humans knew that fire could be used to harden clay into simple pottery. But a crude fire isn't the best tool for the job. It's hard to control the fire's burning temperatures, and you are more often than not at the mercy of the weather. 

So eventually people learned to build enclosed chambers (the earliest kind of modern kiln) in which they could control temperature and airflow. This innovation allowed for the production of much more durable and convenient pottery. The most conservative estimate is that kilns of this type first appeared around 6,000 years ago.

Kilns Throughout the Ages

Archaeological data suggests that the cultures of Ancient Mesopotamia and Egypt were among the first to use modern-style kilns for the production of pottery and bricks.

The culture of Ancient China refined technology by introducing porcelain kilns capable of extremely high firing temperatures, which enabled the production of their world-famous ceramics (fun fact: the secret to producing fine china was once a closely guarded state secret).

The Ancient Romans were the first to employ kilns on a truly mass scale. The ever-growing empire utilized kiln technology to fuel its building boom, which required an unimaginably large number of bricks to be produced daily.

Traditional kilns were perfected in Europe during the Middle Ages. Without kilns, it would've been impossible to produce mortar for all those beautiful castles and cathedrals that span the UK and much of Europe.

Are Modern Kilns Different From Ancient Kilns?

The basic principle behind the functioning of a kiln hasn’t changed much over the centuries. At its core, a kiln is a chamber designed to trap heat, concentrate it, and apply it evenly (exactly how this is achieved depends on what type of kiln it is).

A kiln’s purpose is quite simple. To create a controlled environment where heat can trigger physical/chemical changes in the materials being worked on. For example:

• Turning soft clay into hard, durable ceramic plates.
• Reducing the moisture in wet wood to create premium oak logs.
• Producing high-quality lime from raw limestone.

It’s often compared to an oven for ease of understanding (you may have even seen this in Lekto's advertising). However, while ovens are designed for cooking food at moderate temperatures, kilns can reach temperatures hot enough to melt glass or fuse metals.

Kilns stand apart from furnaces or bonfires because of their control and consistency. Instead of being at the mercy of an open flame, a kiln regulates heat and airflow, creating predictable and repeatable results.

What has changed over the centuries is efficiency. Modern kilns can reach higher temperatures, use less fuel thanks to better thermal insulation and heat recirculation, and are run with automated precision controls on an industrial scale.

Different Types of Kilns and Their Uses

While in English we use a single word to refer to all types of furnaces of this type, kilns made for different purposes feature vastly different designs. A kiln created for one purpose almost invariably cannot be used for another. Some of the most important types of kilns include:

• Pottery Kilns. The most common kind. These are used by various artists and craftspeople to turn clay into durable ceramics. Depending on the energy source (electric, gas, or wood-fired), pottery kilns can theoretically reach temperatures of as high as 1,300°C, but this is seldom needed.

• Brick Kilns. These are typically very large and are designed to bake pre-formed clay into strong and durable construction bricks. Red bricks are typically baked at around 900–1,050°C. White bricks require temps of 1,100–1,200°C.

• Lime and Cement Kilns. These are operated at extremely high temperatures of between 1,200–1,450°C. At these levels, limestone (calcium carbonate) undergoes calcination and breaks down into lime (calcium oxide). Cement kilns are interesting because they are essentially continuous, rotating kilns, designed to maintain heat and efficiency for massive production volumes.

• Glass Kilns. Specialised kilns for melting and forming glass. This process requires precise temperature control at extra high temperatures of 1,400–1,600°C. Lower ranges are used for fusing and slumping glass into shapes. Higher ranges are for full melting, allowing glass to be blown, poured, or molded.

• Wood-Drying Kilns. Last but not least, wood drying kilns are designed to dry freshly felled wood to extra low moisture levels and do it evenly. The goal here is not to burn the wood, but to evaporate its moisture, so temperatures of between 60 and 100 degrees are used. Air circulation and humidity control are even more important than temperature to ensure that the logs don’t crack or warp while drying. A typical drying cycle in the UK reduces wood moisture to under 20%, which is stipulated by the Ready to Burn standard.

How Does a Kiln Work?

As we have seen, kiln designs vary wildly depending on what they are used for. This being said, most still rely on the same basic principles to function.

1. Heat Generation. The vast majority of kilns in the world today are fuelled by either wood, coal, oil, natural gas, or electricity. The choice depends on the application and price of fuels in the region.

2. Airflow Control. Regardless of the application, a kiln will usually have some form of fans or vents to circulate heat evenly throughout the chamber. Without airflow, some parts of the worked on material would remain cooler while others would overheat.

3. Thermal Insulation. Important for efficiency. A good kiln will have thick walls lined with heat-resistant refractory materials to maintain stable temperatures within the kiln and, most crucially, prevent heat loss.

4. Temperature Controls. Most crucial for glass making, but still very important for all kilns, is some ability to control the temperature. Typically, this is achieved by regulating the amount of energy that enters the system.

5. Time and Precision. Different materials require different cycles. For example, firing clay needs just a few hours at sustained heat, while drying wood often requires steady airflow over several days. Most kilns these days are either automated or semi-automated to ensure stable quality control.

The combination of these elements makes kilns reliable tools for transforming raw materials into something stronger, more durable, or simply more useful.

Kilns for Drying Wood (Kiln-Drying Furnaces)

One of the most practical modern uses of kilns is in preparing clean-burning firewood, kindling, and briquettes.. When a tree is first cut down, its logs are heavy with water. When a tree is cut down, 50–70% of its weight is moisture. Trying to burn such a freshly cut (“green”) wood comes with serious drawbacks:

• It’s hard to ignite due to the high moisture content.

• It produces lots of smoke and steam instead of heat as it attempts to evaporate that moisture.

• This smoke leaves behind tar and creosote deposits in your chimney. Over time, these will become fire hazards.

• Wet wood generates less heat. This means you will burn more wood for less warmth.

A wood-drying kiln solves these problems by creating a controlled environment where moisture is steadily and consistently removed without damaging the logs.

How Does the Kiln-Drying Process Work?

1. Preparation. The logs are first cut to size and placed in either ventilated cages or stacks with air gaps.

2. Heating. The kiln is brought up to the desired temperature. This is usually between 60 and 100°C. Ideally, you want to dry the wood at the lowest possible temperature and for the longest possible time. Most manufacturers skimp out on this to save costs, but not Lekto. This is one of the reasons our kiln-dried logs are so well-received.

3. Air Circulation. Fans placed in strategic parts of the kiln circulate hot air through and around the wood. This speeds up evaporation and gets rid of excess moisture.

4. Drying Phase. The logs will steadily become drying until their moisture content is at the desired level. Most brands stop when they reach under 20%. Lekto routinely reaches level of around 10%.
   

Kiln Drying vs. Air Drying

Both kiln drying and natural seasoning reduce moisture in wood, but the difference in speed, quality, and consistency is huge.

 

For anyone who uses a wood-burning stove or open fireplace, kiln drying is the gold standard. It ensures the logs are ready when you need them, without the uncertainty of weather-dependent drying.

Environmental Benefits of Kiln-Dried Wood

One of the biggest advantages of kiln-dried wood is its unparalleled eco-friendliness. While it is true that kiln-drying takes energy to do, this centralized, industrial approach is much more efficient than having the drying occur in your own wood stove and the moisture evaporate as harmful smoke.

• Lower PM emissions. With less water to evaporate, kiln-dried wood produces far less smoke and fewer particulates.

• Less creosote buildup. Cleaner combustion means less tar lining your chimney. This reduces fire risk, means you don't have to have your chimney swept as often, and prolongs the useful lifetime of your wood burner.

• More heat per log. Because the energy isn’t wasted boiling off water, you need fewer logs to heat your home.

• Carbon-neutral heating. Wood is considered a renewable resource. Burning dry wood efficiently reduces the overall environmental impact compared to fossil fuels.

 

FAQs About Kilns and Kiln-Dried Wood

What temperature does a kiln reach?

It depends on the type of kiln in question. Glass kilns can exceed 1,600°C. Wood-drying kilns operate at much lower ranges of 60–100°C to avoid damaging the wood.

How long does kiln drying wood take?

Most hardwood firewood can be kiln dried in as little as 3–7 days. Low end brand tend to have shorter dry times to save on cost. Lekto Woodfuels dries its wood for as long as is required to bring the wood to extra low moisture levels.

Is kiln-dried wood better than seasoned wood?

In most respects, yes. Not needing to evaporate excess moisture, kiln-dried wood is more consistent, easier to light, produces more heat, and emits less smoke. Its only downside is its higher price.

Can you use a kiln at home?

Yes, small pottery kilns are available for home use.

Why does moisture content matter for firewood?

Moisture is the enemy of efficient combustion. Wet logs waste energy evaporating water, creating harmful smoke instead of useful heat. Dry logs provide a clean, efficient burn. 20% and under is considered good enough, but the lower the moisture the better.

Does kiln drying make wood last longer?

Yes. By reducing moisture, kiln drying prevents mould growth, rot, and insect infestation, meaning the logs can be stored for longer without losing their burning properties. This being said, how you store the logs is equally, if not more important.

 

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