How to Ferment your Moonshine Mash

How to Ferment your Moonshine Mash

For many seasoned shiners, fermentation is the easiest step. After all, it really only requires some simple equipment and a whole lot of patience. Check out everything you need to know about how to ferment your moonshine mash. 

The second step to making moonshine is fermentation. Compared to cooking your mash and distilling, this step is pretty much a breeze. Fermentation requires a whole lot of time and not much else from you-other than patience that is. 

That is because the act of fermentation is one that does not require oxygen. So opening your airtight lid to check on the contents is never a good idea-unless you are pretty sure you are done. 



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 image of fermentation


The scientific explanation for fermentation is as follows: the process in which molecules like glucose are broken down anaerobically (without requiring oxygen.) In ethanol fermentation, one glucose molecule is broken down to two ethanol molecules and three carbon dioxide molecules. 


For those of us without a science degree, or simply those who did not pay enough attention during their high school science classes, this is the act in which the beneficial microbes (yeast) react to the sugars in the mash to produce ethanol. Once fermentation is complete you will be removing the ethanol from the water in your wash by distilling it


Ethanol fermentation is only one of the three types of fermentation. There is also lactic acid fermentation and acetic acid fermentation.



Some examples of lactic acid fermentation are sourdough bread, pickles, kimchi and yogurt. Some examples of acetic acid fermentation are apple cider vinegar, wine vinegar and kombucha. 




During the moonshine process, fermentation requires a few key elements in order to happen. One of the most important elements is healthy yeast. This is one of the reasons that many moonshiners choose to make a ‘yeast starter’ to make sure that their yeast is as healthy as possible before adding it to their mash. 






Oxygen: Yeast needs oxygen to jumpstart fermentation and this is why it is important to aerate your mash before fermentation. You can aerate your mash by pouring it from one bucket to another about 12 times or picking up your bucket and shaking it for about 60 seconds. No matter how you choose to aerate, the most important thing is that you do it. Your yeast depends on it. 

PH: A good PH reading is essential to give your yeast a healthy environment to thrive. It is one extra step that many experienced moonshiners understand can make the difference between a good batch and a great one. Refer to our PH section above for how to calculate and adjust the PH of your mash. 

Temperature: Your temperature needs will depend on the manufacturer’s instructions on the yeast you have used. However, keeping a steady temperature is ideal. Make sure that where you are storing your mash is going to be out of direct sunlight or drafts where an even temperature can be maintained. Some people will even wrap their mash with a blanket in order to help maintain an ideal temperature. 

Nutrients: Nutrients are needed as yeast is a living organism and it needs nutrients to survive. Fortunately, grain batches made with rye, wheat or malted barley that are geared towards making a wash of 5 to 10 % alcohol should already contain enough nutrients to allow healthy yeast to thrive. 

Sanitization: This is a good rule of thumb not only during fermentation but during the entire moonshining process. Sanitize all of your equipment and use an airlock filled with sanitized water. 


Want to know more? Check out our guide to using yeast in moonshine.


What Happens to Yeast when it is Stressed? 



Healthy yeast is required for good fermentation. During the fermentation process healthy yeast will produce ethanol and carbon dioxide. However, if the yeast becomes stressed you can have some undesirable effects that can hurt your mash. 



Fusel alcohols: While these chemical compounds will not affect the smell or taste of your moonshine, it will produce a horrible hangover.

While these unwanted compounds can be removed while making your cuts (we will discuss this more in the How to Distill your Moonshine)


It is always better to keep the production of fusel alcohols to a minimum. You can do this by adhering to the recommended temperature on your yeast and keeping it as consistent as possible.


Even a small blip in temperature can encourage this type of unwanted production of metabolic by-product. 


How to Determine your ABV -Alcohol by Volume



One of the things you will notice about moonshining is that there are a lot of scientific terms. This is because as fun as the final product is-making moonshine is really nothing more than a three step science experiment. Along with the scientific methods used to produce your moonshine, there are also scientific terms and tools to learn along the way. 


One important tool in making moonshine is a hydrometer. This is a tool that is used to determine the potential ABV of your mash. It can also be used to determine whether or not fermentation is complete. It is a useful tool in moonshining and is fairly simple to use once you get the hang of it. 


Of course, using a hydrometer is not strictly necessary in making moonshine. Some moonshiners will simply add their mash to their fermentation bucket and wait for the activity to stop in the airlock.

This is perfectly acceptable, especially for those new to the craft. However, if your batches are not coming out properly or your alcohol volumes are low, this could be the reason why. 


Using a Hydrometer


A Hydrometer is used to determine the density or specific gravity (SG) of a liquid in comparison to water. Alcohol is thinner than water so the higher the volume of alcohol, the lower the float will sink. Alcohol has a SG of 1.000 on the hydrometer scale. 


Temperature will also play a role in the hydrometer reading. Your hydrometer should indicate the temperature it is calibrated to (a standard reading temperature is 70°F or 20°C). Your hydrometer should also include a conversion chart if your mash is reading at a different temperature than what your hydrometer is calibrated to. 




Before you add your yeast it is important to measure the gravity in your mash. To do this is fairly simple. Add your liquid mash into your hydrometer to fill it about ⅔ of the way to the top. Insert the hydrometer slowly. Roll it gently between your hands to remove any air bubbles. Read where the surface of the liquid hits the hydrometer. 


This number can help to predict the potential alcohol of your mash.




  • 062 → 7.875%
  • 064 → 8.125%
  • 066 → 8.375%
  • 068 → 8.625
  • 070 → 8.875%
  • 072 → 9.125%
  • 074 → 9.375%
  • 076 → 9.75%
  • 078 → 10%
  • 080 → 10.25%
  • 082 → 10.5%
  • 084 → 10.75%
  • 086 → 11%
  • 088 → 11.25%
  • 090 → 11.5%
  • 092 → 11.75%
  • 094 → 12.125%
  • 096 → 12.375%
  • 098 → 12.75%
  • 100 → 13%
  • 102 → 13.25%
  • 104 → 13.5%
  • 106 → 13.875%
  • 108 → 14.125%



Once you have noticed the activity in your airlock is slowing down, you can take a final gravity reading to determine if your mash is ready for fermentation.


If your reading is 1.000 or less it is definitely done. If your reading is 1.020 or higher, you should wait a few days. However, if your reading has not changed after three days, your fermentation is complete. 


You can then use your readings to help determine what your ABV will be once your distillation is complete. Simply use the following formula to determine your ABV. 


ABV = (OG – FG) X 131


While these numbers are not a 100% guarantee, it gives you a pretty good idea of what to expect after distillation. 

Adjusting the PH of your Mash



While certainly not a step that beginners need to worry themselves with, adjusting the PH of your mash is a helpful additional step to improve the health of your yeast as well as enhance what you can expect to extract from grain. 


A PH scale runs from 1 to 14 with 7 as neutral. Everything below seven is acidic and everything above 7 is alkaline (also called base). 


The ideal PH reading for a mash prior to fermentation is between 4 and 4.5. The ideal PH reading for meads, ciders and wines are 3.4. Anything below a 7 is good for beer. 


To lower the PH of your mash add lemon juice. To raise the PH of your mash add baking soda



You can use precision test strips for testing PH, however not all strips are good for reading the entire PH scale. Make sure you get the right strips for the type of distilling you are doing. You can also use a PH reader that will read the entire scale and give you a precise reading. 



What to Avoid in Fermentation




Sulfur: Is there anything worse than spending a bunch of time and money on making moonshine only to have it taste like rotten eggs? You can avoid this stinky fate by removing as much sulfur as you can from your wash. Most of the sulfur is removed naturally from the carbon dioxide produced by your yeast. Using a yeast starter is a great way to ensure the removal of sulfur. Additionally, using a copper still can also be helpful in removing sulfur during the distillation process. 


The Copperhead All-in-One Stil Kit 



One of the biggest disadvantages of copper stills is that they are often unaffordable, especially for those who are new to moonshining. 

That is why so many people love the Copperhead All-in-One Moonshine Still Kit. This still is the perfect option for those who are looking for a good quallity still at an affordable price. 

The Copperhead features a stainless steel barrel combined with real copper coils that are perfect for removing nasty sulphur from your moonshine. It is also an all-in-one kit that can be used as both a still and fermentor, saving you both time and money. 




Acetaldehyde: This nasty compound is one of the reasons that foreshots should never be consumed (more about that during the distillation section). In beer acetaldehyde tastes like green apples and can happen when a mash does not finish fermentation, when a wash is oxygenated or when a mash sits too long without being distilled. 


Phenols: These nasty compounds can cause your mash to have a medicinal, plastic or ‘band-aid’ type taste. Wild yeast contamination can contribute to the presence of phenolic compounds. To avoid this, it is important to use bottled or filtered water in your mash (to avoid using chlorinated water) and to sanitize all the equipment you use to make your mash. 


Overly Sweet: If your mash is overly sweet there are two possible reasons. One is that you may have ended up with too many non-fermentable sugars before the fermentation process. This can also occur if the mash is not allowed to ferment long enough to convert all of the fermentable sugars into alcohol. 


Overly Dry: If your mash has absolutely no sweetness-or taste-your yeast is to blame. In some cases yeast will power through and consume everything in a mash. This can often happen with champagne yeast or distillers yeast. 

How long does Fermentation Take? 



Fermentation may be the easiest step of making moonshine, but it is also the longest. In general, fermentation takes a steady temperature, good environment and lots of patience. There are several factors that can influence how long your mash will take to ferment. 


Temperature: A steady temperature is ideal for a good fermentation process, but a warmer temperature will speed up the process. It is important to check your yeast package to know what temperature is necessary for good fermentation and go with those guidelines. However, the warmer the temperature the faster fermentation will complete. 


Sugar content: The more sugar in your mash, the longer fermentation will take. This makes complete sense when you consider that fermentation is the transformation of sugar into alcohol. The more work your yeast has to do, the longer it will take for the process to complete. 


Type of Yeast: The type of yeast used will also determine how long fermentation will take. 


How to Tell When Fermentation is Complete



There are several ways to tell when fermentation is complete. One of the easiest ways is to use an airtight container with an airlock for fermentation. The airlock will show activity so you can essentially check in on your mash without lifting the lid. Remember oxygen is not good to be introduced into the fermentation process after aeration. 


With this type of ‘set it and forget it’ system is not exactly scientific, but pretty simple and effective. If you want to use this method simply check your airlock between 18 hours and 48 hours after you add your yeast. You should see bubbles every minute or two. This will tell you that the fermentation is working properly. 





If you don’t see any bubbles in your airlock after 18-48 hours then check to make sure your bucket is airtight. If your bucket is airtight, swirl the contents to mix them well. Check for activity after 12 hours.

If you still do not see any activity after 12 hours add a new yeast starter. Also check to make sure your mash is warm enough. Bread yeast does best in temperatures of about 74-78°F or 23 to 25°C. 

Once you get this confirmation that the process is taking place, you can leave your mash for 14 days. After 14 days, check your airlock. 


Essentially, your airlock will show bubbles to let you know that the yeast is still working. Remember that fermentation is turning the sugars into ethanol as well as carbon dioxide (which is producing those bubbles).


A general rule of thumb is to watch for a cease in activity in your airlock. When you don’t see any bubbles for two days, you can check to see if your fermentation is complete. 






While most home distillers will use the method of fermentation that includes an airtight seal and an airlock to let gas out while keeping air in. However, open air fermentation is another option that many home brewers and even breweries choose. While you may run the risk of contamination, there are also benefits to open air fermentation. 


Tradition: Many moonshiners want to make their shine the old-fashioned way. Traditionally many moonshiners would ferment in the open-air. This could be because of the illicit nature of moonshining and the need to ferment large amounts of mash in secret. 


Gas: By allowing an open air environment gas can more easily. However, it is not as simple as leaving the lid off of your bucket. The ideal shape is wide and shallow to more easily produce esters, which is a reason this practice is popular for many breweries. Esters help add flavor and aroma to beer. 


Open Air Fermentation and Sanitation



There are a few ‘red flags’ when it comes to sanitation. This type of open air fermentation leaves your mash vulnerable to the elements. Dirt, dust, bugs and bacteria can all impact the taste and quality of your final product. 


Also, it is never advisable to put any non sanitized object into your mash, especially your hands!

Using Iodine to Check your Fermentation

Making a mash is basically a 10th grade science experiment. The act of immersing grains in water and adding malt to convert the grains into sugar is a simple one that involves heat and water. 


If you want to check if your mash is ready for distillation you can do so with a simple iodine test.  All you need for this test is:


  • Iodine
  • A white plate (side plate or saucer will do) 
  • A small amount of liquid mash


  1. Keep in mind that you want your mash to be cool when performing the test. This is easily done by placing the small plate or saucer in the fridge for about 30 minutes to get it nice and cool before you test. 
  2. Remove a small amount of liquid from your mash (no solids) and place on the plate 
  3. Add a few drops of iodine. 
  4. If the mixture turns blue there are still some starches in your mash and you need to continue to ferment. 
  5. If the mixture does not change color, you are ready to distill. 
  6. Remember to dispose of your test batch and do not add it back to your mash. 


Using a Hydrometer to Check for Fermentation



The only scientific way to check for fermentation is to use a Hydrometer. Using a hydrometer before adding your yeast to get your Original Gravity Reading (OG) and your final gravity reading (FG) after fermentation can help to determine your ABV (alcohol by volume). 


If all of these steps seem a little too much for your right now, don’t worry. You can simply use your hydrometer to tell you if your mash is done fermenting. Using a hydrometer is simple and it can tell you exactly what you need to know to get started with the distillation process. 




To use your hydrometer is not a difficult task. Simply fill the hydrometer ⅔ of the way full. Gently add your hydrometer and roll the hydrometer slowly in your hands to remove any bubbles.

When the hydrometer falls take the reading. If your reading is 1.000 your mash is ready to distill. If the reading is 1.020 or above, you still need to ferment for a day or two. If your reading is above 1.020 but has not changed in the last three days, your fermentation is complete. 


Clearing your Mash




Clearing your mash is an important step to maintain the integrity of your moonshine. While this is not a necessary step, failing to do this step can result in the particles in your wash/mash getting burned on the bottom of your still. 


Anyone who has ever allowed a sauce to burn on the stove knows that not only does it result in a big mess to scrape off, but also a burn taste in your entire batch. The same is true for moonshine. 


Before you clarify, it is important to release the carbon dioxide from your mash. When the yeast in your mash/wash eats the sugar and turns it into alcohol, it also releases carbon dioxide. It is important to release this carbon dioxide before you clear your mash because it can easily interfere with the process. 


Clearing your mash is essentially getting all the sediment to settle so you can remove the liquid from the particles. If you have trapped carbon dioxide in the liquid it can act as a barrier that stops this process from happening. 



Releasing the carbon dioxide in your mash can be as simple as shaking your fermentation bucket, removing the lid to allow the carbon dioxide to escape and repeating as necessary. You can also use a big whisk to agitate your wash/mash and then let the carbon dioxide escape out of the top. 


Different Techniques to Clear your Mash/Shine


Now that you have removed the carbon dioxide from your mash/shine, it is time to clarify. There are a few different ways to do this, all using different additives and with different time frames. 


  1. Gravity: This is the most cost effective method as it requires you to add nothing to your mash or shine. You simply need to wait for all the particles in your mixture to settle to the bottom of your fermentation vessel. This usually takes about two to three weeks depending on the size of your mash and the ingredients used. 
  2. Bentonite: This is essentially a clay that acts as a sieve for your mash. It will absorb water, expand and then slowly settle to the bottom grabbing the particles from your mixture as it falls. Bentonite will usually clear your mash in about 24-48 hours.
  3. Sparkolloid: This works in the same way as bentonite except you add water to this sparkolloid before you add it to your mash. Sparkolloid will usually clear your mash in about 24-48 hours.
  4. Turbo-Clear: This comes in 2 parts: A and B. These two chemicals are positive and negatively charged.  You put in part A and then about 20 minutes later you put in part B. Your batch will clear in about 24-48 hours. 
  5. Gelatin: Do not use jello! It has to be unflavored gelatin with no sugar in it. The small packs of gelatin come with four different sachets of power. Two sachets should be enough for a 5 gallon mash. However, it is important to note two things for this method. The first, in order for this method to work your mash needs to be chilled. If your fermentation bucket is too large for your fridge or you don’t have the ability to chill your mash then choose another method. The second is that you need to prepare the gelatin with water according to the instructions. Do not simply pour it in. 
  6. Cold crashing: If you have a chest freezer, you can put your mash in the chest freezer. The fatty acids in your mash will solidify and act as a sieve to clarify your mash in about 24-48 hours. 


Once you have clarified your mash you can siphon out the liquid from the top of the fermentation bucket and get ready to do your first run. 


Need help with the next step? Check out Everything you Need to Know About Distillation