A Guide to Mashing and Sparging

This is a step by step general guide to both mashing and sparging.


The Mash  (see https://homebrewonlinebrewblog.wordpress.com/2017/11/02/lets-do-the-mash/ for more detail)


Place your grain in your mash tun, the amount of mashing water can be calculated using the following ratio 2.5:1.  So 2.5 litres to 1 kg of grain this figure can be played with a bit if needed, some find the ratio 3:1 better for their brewing system.  Heat up your strike water (brewing name for mash water) to between 65 and 69 °C. An average mash temperature is 67 °C.  Once your grains are mixed with your mash cold or hot water can be added to achieve the correct mash temperature. Make sure that there are no dough balls and that the grain and water are thoroughly mixed together.  Don’t exceed 75°C as this will stop any enzyme activity and therefore reduce the starch conversion.


Mash for 60 minutes this is often called the saccharification rest. Try to keep the temperature as constant as possible. Whilst your grain is mashing you can heat the sparge water to 75 °C. There isn’t a simple ratio for sparge water quantities.  It can be worked out from your pre boil volume minus the wort you would get without sparging (first runnings). So if you had a 6.7 kg grain bill you would work it out this way:


Grain bill 6.7 kg x 2.5 litres = 16.75 (mash water)

1 kg of grain holds approx 1.1 litres water

Grain bill 6.7 x 1.1 = 7.37 litres of water saturated in the grain, this will never sparge out.

16.75 (mash water) – 7.37 = 9.38 amount of wort extracted if you didn’t sparge. (first runnings)

Pre boil amount 30 litres – 9.38 first runnings = 20.32 This is the amount of sparge water needed to reach a pre boil amount of 30 litres.


Although if you are using the Grainfather there is the Grainfather calculator which works out the water needed, here’s a link: https://www.grainfather.com/brewing-calculators?___store=uk


Mash Out


It’s a good idea to do a mash out for ten minutes.  Heat the mash up to 76 ºC  to preserve the sugar profile. This can be done by putting hot water into the mash to increase the temperature you’ll just need to monitor it closely. Don’t let the mash go above 76 ºC otherwise this could produce some harsh tannins into your brew.




Achieving the correct mash temperature can be awkward depending on the set up you have. Hot and cold water can be added to maintain the mash temperature, keep monitoring the temperature of the grain bed from a few different spots to get the most accurate reading. A 5ºC  variation is fine as long as it does not go above 76ºC . Different enzymes are most active within different temperature ranges.  Alpha amylase enzyme is most active between 68-75 ºC  making sugars which are less fermentable therefore giving the beer a fuller body. Beta amylase enzyme is most active between 54-65 ºC  making sugars that are more fermentable resulting in a drier and crisper beer. 67ºC  is a happy medium.




This is the process of extracting the wort from the mash and is crucial as it determines the pre boil amount.  To calculate the amount of sparge water needed see formula above.  However for more information on this see https://byo.com/article/calculating-water-usage-advanced-brewing.  Avoid temperatures above 79 degrees C as this will increase the amount of Tannin present in the wort which will give it a dry taste.


Sparging can be done in a mash tun that has a false bottom or one of our HBO mash tuns which has a stainless steel mesh bazooka which allows the wort to flow through but not the grain. The wort can then be collected in a kettle ready for boiling. Alternatively there are all grain systems that make mashing and sparging a doddle.  The braumeister is especially useful as there is no need for a separate sparge, saving loads of time.


 Stuck Mash


Whilst sparging you can sometimes encounter a stuck mash this can be due to what you have used in your grain bill such as wheat, oats or unmalted barley. It can also be caused by using too much sparge water at once or losing too much heat in the mash tun.  Ways of avoiding this are slowing down the amount of sparge water used, give the mash a stir to allow the water to trickle through the grain bed or rice hulls can be used in the mash which will help to stop stuck mashes.


Hope this helps and any comments are welcome as brewing is a constant learning curve.


Happy Brewing