How Much Headspace Do You Leave When Bottling Beer?

How Much Headspace Do You Leave When Bottling Beer? When you purchase any commercial carbonated drink, whether it is beer or soft drink, there is always a certain amount of headspace left in the bottle.  So how much headspace should you leave?

The volume of headspace left in the bottle will vary depending upon its size, however, it is most common to see around ¾ to 1 inch of headspace left in the bottle. The easiest way to create this headspace consistently is by using a bottling wand during the filling process. Bottling wands are designed to leave appropriate headspace for both small (330ml) and large (750ml) bottles of beer.

Bottling wands, in my personal view, are an absolute must for anyone that is making homebrew. They make the bottling process extremely easy providing a consistent and accurate fill level. Brewing wands are basically tubes that have the open end connected to the fermenter tap at one end. At the other end, the has a pressure-activated seal that closes as soon as the tube fills with the liquid to be bottled. 

To release the liquid into the beer bottle, the end with the seal on it is pressed against the bottom of the bottle.  The pressure on the seal causes it to open filling the bottle directly from the fermenter. To get the perfect amount of beer into a bottle allow the bottling wand to fill the bottle to the rim and then remove the wand from the bottle. 

When the wand is removed it results in the level of beer in the bottle goes down leaving an ideal amount of headspace for carbonation. This process is fast consistent and repeatable.

Which Is The Best Bottling Wand To Purchase?

There a number of different types of bottling wands that can be purchased. The cheapest ones are made of food-grade plastic and are generally around 1 ft in length. They are relatively simple and will do the job, however, there are a couple of disadvantages to these types.

• The fermentation vessels need to be elevated off the ground to allow space for them to be connected directly to the tap.  The height needs to at least 2 ft above the ground to allow space for the bottles to fit.
• The beer bottles need to be lifted individually out of the case and placed underneath the bottling wand.
• The cheaper bottling wands tend to leak a little so you need to have a bucket underneath the tap to prevent dripping on the floor

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The Professional Stainless Steel Spring Loaded Bottle Filler is one which we recommend because it is only a few dollars more and it has severally advantages over the cheap plastic ones. These advantages are as follows;

• The wand is made of food-grade stainless steel which means it will last longer and will not crack
• The valve on the bottling wand is spring-loaded.  This creates a better seal that prevents leaks
• The wands come with 6ft of tubing which can be used to connect the fermenting vessel to the bottling wand. This feature is extremely advantageous as it allows the bottles to remain in the cases and the wand can be moved from one bottle to the next. This speeds up the filling process significantly
• The professional system comes with a bottle brush that is designed specifically to fit into the bottling wand making it easier to clean.

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Why Is It Important To Have Head Space In A Beer Bottle?

The headspace within a bottle is necessary to maintain an equilibrium between the carbon dioxide that is solubilized in the beer itself and the carbon dioxide in the headspace. Without that gap within the bottle, it would be impossible to hold the carbon dioxide within the beer creating the carbonated effect that beer drinkers love. 

The second important reason that headspace is required is to allow sufficient space for the carbon dioxide gas that is produced in secondary fermentation or priming to pressurize the bottle with causing the beer to be over carbonated. 

The third important reason to allow headspace is to protect the beer from oxidation which can affect the taste. The presence of a headspace does this in two ways. The first is that once the bottle is sealed the secondary fermentation process allows some portion of the oxygen to be consumed by the yeast in the carbonation process.  Secondly, carbon dioxide forms a protective layer over the surface of the beer.  This occurs because carbon dioxide is heavier gas than oxygen and will displace any remaining oxygen at the surface preventing oxidization of the beer.

What happens if you leave too little headspace in a beer bottle?

Insufficient headspace in a beer bottle will result in over-carbonation of the beer. The degree to which this occurs will affect the type of result you will get. In cases where the degree of over-carbonation is slight you can expect to see excess foam escaping from the bottle and you will lose a little of the contents of the bottle. 

In cases where there is a moderate degree of over-carbonation, you can lose the majority of the contents of your bottle when opened. In extreme cases the bottles can explode, this occurs more often when the temperature is warmer and the gas in the headspace expands and the solubility of carbon dioxide decreases. The extreme cases the degree of over-carbonation is not caused solely by a lack of headspace. Other contributing factors can be incomplete primary fermentation or the addition of excess priming sugar, both of which will produce higher volumes of carbon dioxide in the final beer. To learn more about the carbonation of beer click here.

What Happens If You Have Too Much Headspace In A Beer Bottle?

Leaving too much headspace in the bottle creates issues that are a little less dramatic than leaving too little space but it is still problematic.  The first effect you can get is that the beer is completely flat or poorly carbonated.  The second common problem is that the beer goes stale very quickly.  This is due to the presence of excess oxygen that can oxidize the beer which will affect the taste.

Conclusion 

To avoid having to guess the headspace required in a bottle use a bottling wand, as it provides a consistent, quick, easy, and low cost method of filling your bottles.