En formel som kan brukes er : Total vekt på korn x 0,4 x 4 = Vannmengde kornet vil absorbere + ønsket koke volum = Total vannmengde
Formelen er hentet fra Designing great beers.
During mashing, the grains absorb a lot of water that cannot be drained out in the lauter tun. As it turnes out, the weight of the water trapped in the grains is predictable. The total weight of the spent grains mass is 20 % grain and 80% water. Simple, right?
The only thing you have to remember is that the weight of the grain after mashing is not the same as before. During mashing, sugar and protein is extracted from the grains, and that leaves them as shadows of there former selves. Although you can calculate this more precisely for each batch if you really want to, it is safe to assume that the potmash grain mass is about 40% of the weight of the grain you added. So if you mash 10 kg of grain, it will weight about 4 kg when you are finished. Since this 4 kg is 20% of the weight of the spent grains, the weight of the water will equal 4 times the weight of the grain (80% divided by 20%=4). Thus, you will lose 4x4 kg or 16 kg of water in the spent grains. Since the weight of water is about 1 kg per liter, this equals 16 liters. And the you just have to add the boil volume you want.
Formelen er hentet fra Designing great beers.
During mashing, the grains absorb a lot of water that cannot be drained out in the lauter tun. As it turnes out, the weight of the water trapped in the grains is predictable. The total weight of the spent grains mass is 20 % grain and 80% water. Simple, right?
The only thing you have to remember is that the weight of the grain after mashing is not the same as before. During mashing, sugar and protein is extracted from the grains, and that leaves them as shadows of there former selves. Although you can calculate this more precisely for each batch if you really want to, it is safe to assume that the potmash grain mass is about 40% of the weight of the grain you added. So if you mash 10 kg of grain, it will weight about 4 kg when you are finished. Since this 4 kg is 20% of the weight of the spent grains, the weight of the water will equal 4 times the weight of the grain (80% divided by 20%=4). Thus, you will lose 4x4 kg or 16 kg of water in the spent grains. Since the weight of water is about 1 kg per liter, this equals 16 liters. And the you just have to add the boil volume you want.
Ca oppskrift kan ses her 
