Calculating the actual color for a regular beer is described here, and is based on the Malt Color Units (MCUs) which are simply the sum of the pounds of malt times their color for all grains in a batch.

It should be no surprise that the color of the two batches in a parti-gyle will be darker for the first runnings and lighter for the second in most cases. Using the same equation, you can come up with an accurate estimate for the gravity of each of the runnings based on the original gravity of the overall batch. So if we look at a 1.060 total gravity estimate with a 1/3-2/3 volume split which has half the points in each runnings we get 60 points, 0.5 as the points_fraction and 1/3 or 0.333 as the fractional volume: Number_points_ runnings = (Tot_points * Points_fraction / fractional_volume) Next we use the following to calculate the final number of points in this fraction: Once you have the OG estimate for the overall batch, get the number of points by subtracting one and multiplying by 1000, so 1.060 becomes 60 points. This can be done using the method described here, except you use the mash efficiency and total lauter volume instead of the overall brewhouse efficiency and overall batch volume to get your mash OG estimate.

To perform these calculations yourself, start with the OG estimate of the mash runnings using conventional methods. So a 1.060 overall batch OG would translate to a 1.070 first runnings and 1.050 second runnings, with both of equal size. So for example if the total mash had an estimated original gravity of 1.060, we would expect the first 1/3 to have a gravity of 1.090 and the second to have a gravity of half the points or 1.045.įor a 50-50 split by volume, with half of the wort in each batch we get a roughly 58% of the gravity points in the first batch. One common parti-gyle split is 1/3 volume for the first runnings and 2/3 volume for the second which results in a first batch of beer that has twice the points that the second batch will have. This is due to the fact that most of the high gravity wort comes in the first third of the lauter. The rule of thumb for an average mash is that 2/3 of the gravity potential is in the first 1/2 of the runnings. This is important for determining how much grain is required for each beer and also how much liquid to run through each to achieve a target boil gravity. When designing a parti-gyle beer, one is usually concerned with gravity and color of the two beers being created. Often different hop additions, boil additions and yeast are used to create distinct styles from the two runnings depending on the brewer’s preference. Typically a fairly high gravity beer is made from the “first runnings” of the mash, and the second runnings are boiled separately to make a lighter beer. The standard method for Parti-Gyle brewing is to make two beers from a single mash. In the 1700’s and 1800’s it was very common to create a strong beer from the first runnings of the mash and a lighter common beer from the second runnings of a mash. Examples include the various weights of English and Scotch Ale, various grades of Bock, and even variations of Trappist ales.

The method goes back hundreds of years, and many modern sub-styles are examples of light and heavy versions made from a single mash. It offers tremendous flexibility since you can brew two beers of different gravities, and also add different hops and yeast to create distinct beers from one brewing session. Follow brewing is a method for making more than one batch of beer from a single all grain mash.

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