What is a Thump Keg: Comprehensive Guide to Its Purpose and Uses

What is a thump keg? You may have heard the term relating to moonshine production and distilling processes. A thump keg, also known as a doubler, thump barrel, or thump chest, is a secondary chamber used in distillation to enhance the flavor, aroma, and proof of spirits such as moonshine. Thump kegs are typically made from heat-resistant materials like copper, stainless steel, glass, or wood, and are connected to the pot still using copper pipes.

The thump keg is commonly associated with traditional backwoods whiskey stills and serves the purpose of distilling the output of the pot still a second time without having to run the distillate through the still twice. This clever and time-saving design allows for faster distillation while maintaining the unique characteristics of the moonshine being produced.

As an integral part of the distillation process, thump kegs play a crucial role in the production of quality spirits. Distillers use thump kegs to improve their product, save time, and achieve the desired results for their unique concoctions.

What is a Thump Keg

A thump keg is a key component in the distillation process, predominantly used in producing alcoholic spirits. It is placed between the still pot and the condenser, and serves to increase the alcohol content by performing a secondary distillation.

Made from heat-resistant materials like copper, stainless steel, glass, or wood, the design and size of thump kegs vary according to the user’s needs and preferences. Copper, in particular, is highly favored because of its excellent heat-conductivity properties. However, stainless steel offers durability and does not impart any flavors to the distillate. Glass allows for easy observation of the process, while wood is primarily used for traditional thump kegs.

Your choice of material will depend on factors such as budget, availability, and preference for specific characteristics during the distillation process. It is essential to invest in a high-quality thump keg that suits your requirements and meets safety standards.

In essence, the thump keg receives vapors from the still pot, which then condense and form low wine—a mixture of water and alcohol. The low wine subsequently boils, releasing vapors rich in alcohol content that rise and enter the condenser. This process enhances the strength and purity of your final product by removing unnecessary water and impurities in the mixture.

The use of a thump keg essentially speeds up the alcohol distillation process and proves to be a valuable asset. It effectively allows you to achieve a higher alcohol content or proof in a shorter amount of time—contributing to more efficient and refined distillation.

Understanding the Distillation Process

Pot Still Distillation

Pot still distillation is a traditional method used to separate alcohol from a fermented mixture. In this process, you heat a liquid mixture, also known as wash or mash, in a pot still, which is a large, copper container. As the temperature rises, the alcohol in the wash begins to vaporize since it has a lower boiling point than water. The alcohol vapor travels through a condensation coil, where it cools down and condenses back into liquid form. This liquid, called low wine, contains a higher concentration of alcohol than the original wash.

To increase the alcohol content further, you can perform a second distillation with the low wine by repeating the same process. The result is a distilled spirit with a higher concentration of alcohol.

Column Still Distillation

Column still distillation is a more modern approach, often used for large-scale alcohol production. A column still, also known as a continuous still, consists of a tall, vertical column filled with a series of perforated plates or trays. The wash is fed into the column, and as it rises, it encounters the trays. The trays help separate alcohol vapor from the mixture at various boiling points. The alcohol vapor rises to the top of the column and then passes through a condenser to produce a distilled spirit.

Column stills are more efficient in terms of energy consumption and the amount of distilled alcohol produced in a given time. They also continuously distill the wash, which reduces the need for multiple pot still distillations.

Both methods significantly impact the final product’s taste, texture, and quality, allowing distillers to craft unique spirits.

Components of a Thump Keg

Main Boiler

The main boiler is the heart of a thump keg system. It’s where your initial mash or wash is heated to separate the ethanol from water through a process called evaporation. Typically, the main boiler is made from materials such as copper or stainless steel, as they are heat-resistant and efficient in conducting heat. The size of your boiler will determine the size of your thumper keg, which should be around 25% to 40% of the main boiler’s size.


After the vapors leave the thump keg, they then move into the condenser. The role of the condenser in your thumper keg setup is crucial to transform the vapors back into a liquid with a higher alcohol content. This is achieved by cooling the vapors, causing them to condense back into liquid form. The materials for constructing condensers are typically the same as those used for the main boiler, such as copper or stainless steel, as they are excellent conductors of heat and offer excellent durability.

Reflux Column

A reflux column is an optional component of a thumper keg system that can help further purify the product. It operates by allowing some of the vapor to condense and flow back into the thump keg, in a process called “reflux”. By doing this, the ethanol concentration in the final product becomes higher, resulting in a more distilled and purified output. To implement a reflux column into your system, you need proper planning and construction, as it can add complexity to your setup. However, it might be a worthy investment if you aim to achieve a higher quality final product.

Use and Function of a Thump Keg

A thump keg is an essential component in the distillation process, specifically designed to increase the alcohol content and enhance the flavor of your spirits. It serves as a secondary distillation chamber, typically made from copper, steel, or wood, that sits between the primary still pot and the condenser.

When using a thump keg, you will be able to achieve a high-proof spirit with more efficiency. As the vapor from the primary still pot passes through the thump keg, the wash inside helps to further condense and strip away impurities. This process aids in creating a smoother-tasting and higher-proof distillate.

Moonshiners and distillers use thump kegs for various washes and spirits. Here are some benefits you’ll notice when incorporating a thump keg into your distillation process:

– Alcohol Content: The thump keg helps to increase the alcohol content of your final product by distilling the vapor a second time. This results in a spirit with a higher proof.

– Flavor: Thump kegs can contribute to a better-tasting final product. The resulting distillate has a cleaner and more refined flavor profile by removing impurities and unwanted compounds.

– Spirits: A thump keg is particularly beneficial when making bourbon or moonshine, as those high-proof spirits require additional distillation to achieve their unique characteristics.

Remember, the size of your thump keg plays a crucial role in its effectiveness. Choosing one that is 25% to 40% the size of your main boiler is essential. This proportion will allow the thump keg to efficiently separate the alcohol from the wash and improve overall distillation.

Materials and Making of a Thump Keg

When building your own thump keg for home brewing, it’s essential to choose the right materials that can withstand heat and make a proper connection between the still and the condenser. Some of the most commonly used materials for constructing a thump keg include stainless steel, copper, and wood.

Copper is popular due to its excellent heat conductivity and traditional appeal. You can use copper tubing or copper pipes to connect the keg to your still and condenser. This material helps maintain a proper temperature during the distillation process and removes sulfur compounds, resulting in a better-tasting final product.

Stainless steel is another suitable material for a thump keg. It is durable, corrosion-resistant, and easy to clean. Just like with copper, you can use steel pipes or tubing to create the necessary connections. Consider using stainless steel if you prefer a material that requires less maintenance and offers a sleek appearance.

Though less common, wood can also be used to construct a thump keg. Make sure to choose a wood type that can withstand high temperatures and doesn’t react with the alcohol, such as oak or maple. Keep in mind that wooden vessels may require more frequent maintenance and might impart a unique flavor to your final product.

First, determine the appropriate size for your brewing setup to create your thump keg. It should be approximately 25% to 40% the size of your main boiler. Next, create a sturdy vessel using your chosen material, secure the necessary connections, and maintain a tight seal to prevent any leaks or air gaps during the distillation process.

If you’re new to home brewing and looking for a complete setup, consider purchasing a home brewing kit. Many kits include all the components you need for successful brewing, such as the thump keg, still, and condenser. This can be an excellent way to learn the process and produce quality spirits in the comfort of your home.

By choosing the right materials and following proper construction techniques, a well-made thump keg can greatly enhance your distillation process and help you create a high-quality final product.

Understanding the Sound and Size

The thump keg, an essential component of a traditional still, is designed to redistill the output of the pot still for a second time without having to run the distillate through the still twice.

The term “thump keg” likely comes from the thumping sound produced during the distillation process. The bubbles of alcoholic vapor within the keg make the liquid thump against the sides of the keg, creating this unique sound. This thumping sound not only gives the thump keg its name but also indicates that the distillation process is underway.

As for the size of the thump keg plays a significant role in the efficiency and effectiveness of the secondary distillation process. Generally, a larger thump keg can hold more liquid and provide a larger surface area for the vapor to condense and mix with the remaining liquid in the keg. Consequently, this larger size enables a more thorough secondary distillation process, resulting in a higher-proof spirit.

However, it’s important to strike a balance in choosing the size of your thump keg. While larger kegs offer the benefits mentioned above, they can also slow the distillation process due to the increased volume of liquid that needs to be heated. On the other hand, a thump keg that’s too small might not provide enough surface area for adequate distillation, leading to a lower-quality product.

Influence on the Flavor

Impact of Fruits and Herbs

Adding fruits and herbs to your thump keg can greatly influence the flavor of your distilled spirits. You can experiment with different combinations to create unique and exciting flavors. For example, using fruit like apples, pears, or peaches can give your distillate a fresh, fruity taste. Herbs such as mint, lavender, or rosemary can give your spirits a more complex, botanical flavor profile. The natural oils and esters found in fruits and herbs will be carried over during the distillation process, imbuing their essence into the final product.

Impact of Spices

Spices can also significantly impact the flavor of your spirits when used in the thump keg. Including spices like cinnamon, cloves, or even chilies can create a warm, spicy, or even a slightly fiery flavor in your finished product. Like with fruits and herbs, the oils and ketones from these spices will be transferred during distillation, leading to a more distinctive taste in your spirits.

Role of Raw Ingredients

The raw ingredients you use in the initial fermentation process will also play a crucial role in the overall flavor of your spirits. Using different types of grains, such as corn, rye, or barley, will result in varied flavor profiles. The yeast you select for fermentation can also affect the final product’s flavor and aroma. Pay close attention to the quality and choice of raw ingredients, as they will have a lasting impact on the final flavor of your spirits.

How to Use a Thump Keg

As a home distiller, using a thump keg can significantly improve the quality and efficiency of your distillation process. Here’s a step-by-step guide on how to use a thump keg:

1) Select the right size and material: Choose a thump keg that is 25% to 40% the size of your main boiler. Materials commonly used for thump kegs include copper, steel, and wood.

2) Connect the thump keg to your still: Typically, thump kegs are connected using copper pipes. Place the thump keg between the still pot and the condenser. Make sure the connections are secure and airtight to prevent leaks.

3) Fill the thump keg with liquid: Depending on your preferences, fill the thump keg with liquid. This could be your low wine from the primary distillation, water, or a mixture of both. Ensure that the liquid level is below the inlet pipe, allowing enough room for the vapor to enter the thump keg.

4) Add flavoring agents (optional): If you want to experiment with different flavors, you can add fruit, herbs, or spices to the thump keg. These will be steam-extracted along with the alcohol during the secondary distillation process.

5) Begin the distillation process: Turn on your still and let the primary distillation begin. As the vapors from the still pot move towards the condenser, they will pass through the thump keg. The vapor will bubble through the liquid in the thump keg, providing a secondary distillation and further refining your spirit.

6) Monitor the process: Pay close attention to the distillation process’s temperature, pressure, and flow. Make adjustments as needed to ensure a smooth and efficient operation.

Quality Considerations

When it comes to thump kegs, considering the quality of both the keg itself and the resulting alcoholic beverages is essential. To ensure you achieve the best possible outcome, here is some advice on what aspects to pay attention to.

Firstly, carefully choose the materials used for constructing the thump keg. The most common and popular choice is copper, as it offers excellent heat conductivity, and it helps to remove unwanted sulfur compounds. Stainless steel is another option, as it’s robust and corrosion-resistant, but you may sacrifice some of the benefits that copper provides.

Secondly, consider the size of your thump keg. The volume should be around 25% to 40% of your main boiler’s size to achieve optimal performance. A size within this range will allow for efficient heat transfer and effective distillation of the initial liquid.

When it comes to the quality of the alcoholic beverages produced in a thump keg, temperature control is key. Aim for consistent heating throughout the process to prevent any significant temperature fluctuations that may affect the outcome. This may require investing in a heat source with adjustable temperature settings.

Lastly, cleanliness is vital. Before starting each distillation process, thoroughly clean your thump keg and ensure there’s no residue from previous batches. It’s also good practice to sanitize all tubes and connections to maintain a sterile environment, leading to higher-quality output.

Thump Keg in History

During the Prohibition era, the demand for homemade spirits led to the innovation and use of thump kegs in North America. Thump kegs, also known as doublers, thump barrels, or thump chests, have a long and storied history, particularly in the backwoods regions where settlers were known to distill their own whiskey.

People with limited resources and a strong desire for self-sufficiency characterized these regions. These settlers often had to make do with what they had on hand, and as a result, the thump keg emerged as part of the traditional hillbilly still.

You may be curious about the purpose of a thump keg. It serves to distill the output of the pot still a second time, without the need for running the distillate through the still twice. This clever design element is efficient and cost-effective as it utilizes waste heat from the still pot for its function.

In the past, many shiners preferred to use a wooden barrel for the thump keg, mainly because it lost less heat than a copper or steel version. Today, thumper kegs can be made of wood, copper, and steel.

A brief historical context: The Prohibition era in the United States lasted from 1920 to 1933. This period saw the widespread illegal production, transport, and sale of alcohol due to the nationwide ban. With moonshining being a significant part of the secret liquor trade during this time, the thump keg played a critical role in facilitating the production of high-quality spirits.

Given its unique role in distillation, the thump keg has remained an integral component of traditional backwoods whiskey stills in North America. It has played an essential part in the cultural history of settlers and their determination to maintain their way of life and traditions, despite hurdles like the Prohibition era.

What is a Thump Keg? FAQs

How does a thumper keg function?

A thumper keg operates as a secondary distillation container placed between the still and the condenser. It’s typically connected to the still using copper pipes. As the vapors from the still enter the thumper keg, they heat and bubble through the liquid inside—leading to further distillation and a higher-proof output.

What is the purpose of using a thump keg?

The primary purpose of a thumper keg is to increase the efficiency of the distillation process by distilling the output of the pot still a second time. Implementing a thumper keg helps concentrate the alcohol content, enhancing both the flavor and the potency of the final distillate, without needing to run it through the still twice.

How can one make their own thumper keg?

To create your own thumper keg, you’ll need a heat-resistant container made of materials such as glass, copper, stainless steel, or wood. You’ll also need high-quality copper tubing to connect your still to the thumper keg, and a suitable connection to your condenser. Remember that safety should be your top priority; ensure you have proper ventilation and safety equipment while attempting any DIY distillation project.

What liquid should be put in a thump keg?

The liquid put inside a thumper keg should be a mixture of the starting wash and the output, known as distillate, from the still. The ratio may vary between 25% to 50% of the distillate with the remaining portion being the starting wash. This helps create more flavorful and higher-proof final output.

Can a mason jar be used as a thumper?

Although a mason jar can technically be used as a thumper keg, it is not recommended due to the likelihood of the glass cracking under the heat and pressure generated during the distillation process. Investing in heat-resistant materials like copper, stainless steel, or specifically designed thumper kegs built to withstand these conditions is best.

Where can one find a thump keg for sale?

Thumper kegs can be found for sale through various online retailers specializing in distillation equipment and homebrewing supplies. You may also want to explore local homebrew shops or flea markets that might carry thumper kegs or other related materials. Always ensure that you are buying from a reputable source to guarantee high-quality and safety-compliant products.

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