TBN + First Wort Gravity

Way over at The Brewing Network, a fellow forum user had asked if there was a spreadsheet that performs John Palmer's water addition for step-mashing calculations. It seemed a good enough reason to put one together, so that's what I did. If you download the spreadsheet that I make available, you'll notice that you can do the calculations in the tab labelled "Infusion Calculations." Let me know what you think if you end up using it.

Also, I stumbled upon this when searching for a way to solve a friends problem with doing AG in a 20 quart kettle on a stovetop. He was fretting about having a 20 quart brewpot and trying to do a full 5 gallon all-grain batch on his stovetop. We talked a bit about sparging, and it occurred to me that he could do a no-sparge brew if he had volume concerns. Of course, it struck me that I didn't know exactly what sort of original gravity to anticipate from first runnings, so I consulted Google. Lo and behold, I was granted the following from an old post on Probrewer.com.

As Ashton notes, Kunze* suggests that a first runnings of 20 Plato can be achieved by mashing 100 kg of malt with 3 hectoliters of water. Being from the US, these numbers don't mean a whole lot to me. Let's see what we get when we convert.

100 kg = ~220 pounds.
3 hectoliters = ~ 79.2 gallons, or ~317 quarts.

We then divide 317/220 to get ~1.44 quarts per pound. So, we now know the ratio in US units.

Ashton then goes on to provide a calculation for determining degress Plato of your first runnings from the mash thickness, assuming that Kunze is correct. It looks like this:

First wort gravity = (3 hl/100 kg malt)(20 Plato)/(3.2 hl/100 kg malt)
First wort gravity = 18.75 Plato

Of course, one can't just replace the "(3hl/100 kg malt)" with "(317g/200 lb malt)" and expect to get the same type of answer.

However, we can quickly determine a factor to make this easy. 3/100 = 0.03. 317/220 = 1.44. These two figures are separated by a factor of 48. That is 0.03*48 = 1.44 and 1.44/48 = 0.03.

Let's call (hl water/kg malt) Rm. In this case, Rm = 0.03. Let's call (quarts water/lbs malt) Ru. In this case, Ru = 1.44. 1.44/48 = 0.03. Likewise, if you wanted to determine the Rm for, say, 1.25 quarts per pound. Simply divide 1.25/48. The result is approximately 0.026. That is, it's the same ratio as 2.6 hl to 100 kg malt. Things are looking a bit simpler now.

To determine the degrees Plato of the first runnings of a mash with a water:grain ratio of 1.25 quarts per pound, we do the following.

1.) Divide 1.25 by the factor of 48. 1.25/48 = 0.026. That is 2.6 hl/100 kg malt.

2.) First Wort Gravity = (3hl/100 kg malt)(20 Plato)/(2.6 hl/100 kg malt)

3.) (0.03*20)/(0.026)

4.) (0.6)/(0.026) = ~23.1 Plato, = ~1.092 SG.

Long story short - here's an ultra-simple calculation that you can do to figure this out without exploding your brain:

.6/(X/48)

Replace X with your quarts per pound ratio (1.5, for example), and it will spit out the gravity of your first runnings in degrees Plato. Ta da!

In Excel speak, =SUM(0.6)/(B1/48)

Okay, so all the math is there, but does it work? After all Kunze notes his results are based not just on a ratio, but on a much larger amount of grain and water than the typical homebrewer can handle. If I mash ten pounds of malt at a rate of 1.44 quarts per pound, can I also expect to get a first wort of 20 Plato (~1.080 SG)? I don't know. This, to me, is the most interesting part. Experiment designs are currently being considered. I'll be sure to post about it as this side project gains more momentum.

Lastly, I want to create a better logo for the top of the page. I was thinking of putting the title of the blog into a sort of faux-calculation. For example, 'Makin'' might be translated to m4(k)/n. I haven't tried to "convert" 'them there beers' as of yet, but I'll post when I think of something. Suggestions, as always are welcome.

Happy Brewing!

*That is, Wolfgang Kunze. Author of the highly respected Technology Brewing and Malting.