What is a Mash Tun Used For?

Learn what a mash tun is used for, how to use a mash tun, some tips on homebrewing with one and common troubleshooting help.

BREWING EQUIPMENT

Mat Stuckey

9/18/20238 min read

What is a Mash Tun Used For?

A mash tun is one of the most essential vessels used in all-grain homebrewing. But if you're new to brewing your own beer from scratch, you may be wondering - what exactly does a mash tun do?

In short, a mash tun is used to soak and steep crushed grains in hot water to convert their starches into fermentable sugars. This sweet wort is then lautered from the grains and boiled, fermented, and conditioned to produce beer.

Below we'll explore the mash tun's key functions in detail, how it differs from a lauter tun, different types, design considerations, and much more. Let's dive in!

The Core Purpose of a Mash Tun

The primary goal of the mash tun is to create ideal conditions for converting the starches within malted grains into fermentable sugars that yeast can turn into alcohol and CO2.

It achieves this by providing a vessel to mix together crushed grain and hot water, held at a consistent temperature for an extended mash rest. This "mashing" process activates natural enzymes present in malted barley and other brewing grains, breaking down their starches through enzyme activity.

Without a mash tun, all-grain homebrewing would not be possible. It provides the foundation for extracting sugars from grains and producing wort - the sweet liquid that becomes beer after fermentation.

Why Use a Mash Tun for Brewing?

For brewers seeking to make beer from scratch using raw ingredients, a mash tun is mandatory equipment. Here's why it's indispensable:

  • Enables all-grain brewing - Steeping and mashing grains unlocks their fermentable sugars. This imparts deeper, richer flavours compared to extract brewing.

  • Promotes consistency - A dedicated vessel makes repeating your process and recipes easier batch to batch.

  • Dials in mash efficiency - Various design factors help maximise your sugar yields from grain.

  • Customization - Change variables like mash thickness, temperature rests, and duration to influence wort character.

  • Scalability - Mash tuns can be sized up or down to match your batch requirements.

While extract brewing with liquid or dry malt extract avoids mashing, many homebrewers eventually graduate to all-grain brewing for greater complexity and control over the finished beer. A mash tun is a worthwhile investment at this stage.

How Does a Mash Tun Differ from a Lauter Tun?

The terms "mash tun" and "lauter tun" are sometimes used interchangeably, but they refer to different stages of the brewing process. Here's how they differ:

  • A mash tun is used for the initial mashing step, hydrating grains and converting starches to fermentable sugars via enzyme activity.

  • A lauter tun is used afterward for the separation and filtration of sweet wort from spent grains through methods like sparging and recirculation.

For small-scale homebrewing, both functions are often combined into a single vessel for convenience. But in commercial breweries, separate mash tuns and lauter tuns are more common.

While a mash tun's core purpose is the mashing process, many homebrew designs incorporate features to assist with lautering tasks as well like false bottoms and sparge arms. We'll cover these shortly.

Key Considerations for Mash Tun Design

Whether DIY or store-bought, several factors impact a mash tun's performance and efficiency:

Size

The mash tun size dictates how large of a grain bill and batch volume you can produce. Size your tun appropriately for your target batch sizes.

Shape

Cylindrical vessels make recirculation and uniform mash temperature easier compared to square coolers. Round also maximises volume.

Material

Stainless steel offers durability and wort clarity but at a higher cost. Food-grade plastic is affordable but can scratch and harbour bacteria.

Insulation

Insulated mash tuns maintain steady mash temperatures throughout long rests. Less temperature fluctuation means better conversion.

False Bottom

A slotted false bottom prevents compacting and aids lautering by filtering grains. Perforated stainless or a malt pipe are options.

Thermometer

A thermometer is vital for hitting target mash temperatures accurately. Digital readouts are convenient.

Modifications

Consider valves, sight glasses, ports, sparge arms, and pumps to customise your system.

Maximise efficiency and repeatability by selecting a thoughtfully designed mash tun suited to your brewing goals.

Mash Tun Materials and Components

Mash tuns can be made from many different materials, each with their own pros and cons:

Stainless Steel

Pros: Extremely durable, non-reactive, easy to clean and maintain. Provides fast, efficient heating. Cons: More expensive than other options. Requires welding for DIY builds. We like the Klarstein Maischfest for a well priced, strong performing steel kettle.

Plastic Coolers

Pros: Very affordable and widely available option for homebrewing. Insulated to maintain temps. Cons: Can scratch and harbour bacteria. Not as effective at indirect heating.

Aluminium

Pros: Affordable, lightweight, and conducts heat well. Easy to weld or modify. Cons: Reactive to wort pH, can cause metallic flavours. Requires protective coatings.

Wood

Pros: Traditional material that allows for beautiful craftsmanship. More sustainable option. Cons: Difficult to seal and maintain. Can harbour microbes without diligent sanitisation.

Common components to enhance a plastic or stainless mash tun include a ball valve for drainage, a sparge arm, a thermometer, and sight glasses. Consider your budget, skill level, and preferred brewing methods when selecting materials.

The Step-by-Step Mash Tun Process

Operating a mash tun involves a series of key steps:

  1. Heat your strike water - Heat water alone in the mash tun or an external hot liquor tank to hit your target mash temperature.

  2. Dough in - Mix your crushed grains into the strike water gently to avoid dough balls and ensure even saturation.

  3. Monitor temperature - Check the temperature and adjust if needed to hit your planned mash rest temp.

  4. Mash rest - Maintain this temperature for 60 minutes or more to allow the mash to convert starches to sugars.

  5. Recirculate - Flow wort through the grain bed and back into the tun to set grain bed, clarify, and balance temperature.

  6. Mash out - Raise the temperature to 168°F - 172°F to halt enzyme activity and improve wort viscosity.

  7. Lauter - Sparge or drain the wort from the grains into your brew kettle while avoiding a stuck mash.

  8. Clean - Clean and sanitise thoroughly after each use to avoid contamination.

Following this standard mash routine will produce the sweet wort needed for brewing beer time and time again.

Designing an Efficient DIY Mash Tun

Building your own mash tun allows customization but demands careful planning. Follow these tips:

  • Select an appropriately sized vessel for your batch goals - bigger is better for higher efficiency.

  • Choose a cylindrical cooler or kettle over a square shape for ease of recirculation.

  • Install a false bottom 2-3 inches above the drain port to act as a filter bed.

  • Add a ball valve drain port roughly 2 inches up from the tun bottom to allow wort drainage.

  • Include a thermometer, sight glass, and spray ball sparge arm if possible.

  • Insulate with reflection insulation or neoprene for consistent mash temperature.

While more labour intensive, you can gain functionality at a fraction of the cost of commercial systems when designing your own mash tun.

Going Electric: eBIAB Mash Tuns

For convenience and consistency, electric mash tuns have grown in popularity. Key benefits include:

  • Integrated electric heating elements allow precisely hitting mash temps.

  • Automated recirculation and mash schedule control reduce hands-on work.

  • Insulated to maintain rest temperatures throughout the mash.

  • All-in-one eBIAB systems combine mashing, lautering, and boiling into a single vessel.

Electric mash tuns require a bigger upfront investment but make the brew day easier. They are a great option for those seeking more automation.

Tips for Getting the Most From Your Mash Tun

Follow these best practices to maximise your mash efficiency and results:

  • Fine crush - A consistent, fine crush is vital for good extraction and clear wort.

  • Accurate temperatures - Hit each rest dead-on and minimise fluctuations.

  • Gentle dough-in - Gently stir in grains to evenly hydrate and avoid clumping.

  • Maintain thickness - Keep grains loose but not too thick by stirring and recirculating.

  • Sparge slowly - Drain wort and rinse grains leisurely to optimise sugar extraction.

  • Clean thoroughly - Scrub and sanitise after each use to avoid fouling or contamination.

Taking the time to mash properly and care for your equipment will reward you with higher yields and better beer.

Mash Schedules and Rests for All-Grain Brewing

One key advantage of mashing in a tun is the ability to program temperature steps and rests. This allows customising the mash to suit different beer recipes and styles. Common mash schedules include:

Single Infusion

  • Mix grains and hold at ~150°F for 60 minutes.

  • Simple but less flexibility.

Two Rest Mash

  • Dough in at ~150°F, rest for 30 minutes.

  • Raise to 158°F and rest another 30 minutes.

  • More fermentability.

Step Mash

  • Start at ~145°F for body, raise to ~155°F for conversion, then mash out at ~168°F.

  • Enhances complexity.

Beta Glucan Rest

  • Start at ~95°-120°F for better lautering, then raise to saccharification temp.

  • Improves yield and wort runoff.

Test out different mash schedules to influence the body, aroma, attenuation, and mouthfeel of your homebrewed beer.

Choosing Your Mash Tun Size and Batch Capacity

Determining the right mash tun size comes down to balancing several factors:

  • Your typical target batch sizes - bigger is better for maximising efficiency.

  • Available space - Larger tuns take up more room in your brewery.

  • Grain bill sizes - Can your tun easily accommodate the grain required in your recipes?

  • Production goals - Only size up if you plan to brew significantly larger batches.

  • Budget - Larger and stainless mash tuns come at a higher cost.

For homebrewing, 10-15 gallon mash tuns are common, allowing 5-10 gallon batch sizes. Make sure to factor in losses and Hot liquor tank space as well. Think through your brewing goals and system constraints before selecting your mash tun capacity.

Additional Brewing Tasks a Mash Tun Can Assist With

While mashing is the primary purpose, a mash tun's design can lend itself to aiding additional brewing tasks:

  • Heating strike water - Many homebrewers heat their initial brewing liquor in the mash tun directly.

  • Lautering wort - Features like false bottoms help filter wort from spent grains when sparging and lautering.

  • Infusions - A mash tun offers a convenient vessel for steeping specialty grains to add colour, flavour, or body.

  • Cleaning and sanitising - The mash tun should have room to easily scrub all surfaces after brew day.

Consider how incorporating features like a sparge arm or ball valve can allow a mash tun to pull double duty across multiple stages of your brew day.

Choosing the Best Mash Tun for Your Needs

Selecting a mash tun to match your budget and brewing goals takes some research. Keep these tips in mind when evaluating your options:

  • Stainless steel offers durability and wort clarity if you can afford the higher cost.

  • Plastic coolers provide an extremely affordable DIY option for most homebrewers.

  • Look for a cylindrical shape for better efficiency and recirculation than a square cooler.

  • Opt for at least 1.5 quarts of capacity per pound of grain to maximise your mash efficiency.

  • Prioritise kettles and coolers with thicker walls that better retain heat.

  • Upgrade to electric heating elements and pumps down the road to increase automation.

Choosing the right mash tun for your needs will help you achieve higher yields, dial in your system, and brew consistent beers time after time.

Common Problems and Troubleshooting With Mash Tuns

Like any brewing equipment, mash tuns can encounter issues. Be prepared to address:

  • Temperature drops - Insulate your mash tun and preheat before mashing in to maintain temps.

  • Poor conversion - Ensure you are hitting optimal saccharification rest temps and pH.

  • Stuck sparges - Avoid over crushing grains, don't overfill tun, and recirculate to set grain bed.

  • Low efficiency - Could be caused by pH, crush size, mash thickness, or sparging issues.

  • Infection - Scrub and sanitise thoroughly after each use. Replace plastic tuns with scratches.

  • Weld leaks - Have a pro re-weld any leaks on stainless steel mash tuns to prevent corrosion.

Familiarise yourself with common mash problems so you can quickly troubleshoot any issues in your brewdays.

Mastering Your All-Grain Mash with a Tun

Equipping your homebrewery with a quality mash tun is a milestone on the path to all-grain brewing. This allows you to unlock greater complexity and customisation in your recipes.

We hope this guide gives you a better understanding of the mash tun's importance and how to wield this essential vessel. With the fundamentals down, you'll be ready to start mashing and unlocking the full potential of brewing ingredients.

If you're looking to take a deeper dive into all-grain brewing, be sure to check out these additional articles:

  • Setting Up Your All-Grain Brewery

  • How to Brew Your First All-Grain Batch

  • Top Tips for Designing Your Mash Schedule

  • All-Grain Brewing Mistakes to Avoid

Happy mashing and brewing! Let us know if you have any other questions. We're always happy to talk shop. Want more tips on homebrewing beer? Head over to the Brewpedia blog for loads more.