Grain weighed and crushed? Check.
Mash temperature sitting at about 146? Check.
Homebrew poured into your favorite pint glass? Check.
Now we play the waiting game.
The mash for this recipe will last 60 minutes and the benefit of using a converted cooler for a mash tun is that there’s no open flame involved during this hour, so you can feel free to run to the brew store for the Irish moss that you forgot to pick up, or run out and grab some groceries for dinner. However, by the end of these 60 minutes, you’ll want to have your sparge water heated and ready to go for the next step — the sparge.
The goal of the sparge is to rinse the grains of their sweet nectar and saturate the grains with water, rather than the delicious wort. A recipe like this will require about four gallons of sparge water, and I’ll talk more about this volume later.
Next we’ll heat up our calculated volume of sparge water to about 15-18 degrees above our target mash-out temperature of 170 degrees. (Remember that old 5-gallon kettle you used for extract batches? Gently remind it that it is still very useful and loved, but that its new job will only be with sparge water heating.) The increase to 170 degrees will allow us to liquefy the mash a little bit and allow it to flow out of the mash tun as easily as possible. If we happen to raise the mashout temperature too high an increase tannin extraction occurs, which makes for some unhappy taste buds.
So now that we’ve got our water heated up to temp and ready to go, we’ll start by popping the lid off the tun, and doing a step called the “vorlauf.”
Grab yourself an empty pitcher, and bust open the drainage valve on your mash tun. You’ll notice a few flecks of grain material that flow through initially, and then it starts to clear up. This typically happens for me about 3/4 of a gallon into the vorlauf. Once you’ve got some clear wort flowing through, carefully pour the vorlauf volume back into the mash tun along the sides of the tun so as not to disturb or mix up the grain bed. This will allow for a nice, clear flow of wort.
Once you’ve drained your mash tun entirely, calculate how much wort is in your boil kettle. Pre-boil, you’ll want to end up with five gallons, plus an extra gallon or so of wort per hour of boiling. Since this recipe is a 60 minute boil, we’re looking for a total of six gallons of wort.
Due to grain absorption during the mash you’ll probably draw off about two gallons of “first wort” from our soon-to-be Kolsch. That means we need four more gallons of sparge water to make it to our target pre-boil volume. The next step is to take two gallons of our pre-heated sparge water and dump it into the mash. Give it a bit of a stir, repeat the vorlauf process and run the valve wide open until you get through the first two gallons of the sparge.
Now theoretically, you’ll have exactly two gallons of sparge water left over, and you can throw in the tun, vorlauf and let it all drain into the kettle to get exactly six gallons. However, we don’t live in a perfect world, and these calculations are typically tricky to hit spot on. If you have a little bit extra sparge water left, you can put it all in the tun and simply cut off the drain when you hit your target volume of water in the kettle. This works just fine, and is actually somewhat ideal in a way.
If you have less than two gallons, you’ll have to add water, heat it up and add it to the mash tun. Finally, if you have a lot more than your necessary volume of water left, you’ll have to estimate and again, cut it off when you get to your target volume.
So what you’ve done by adding the volumes in two separate additions is rinsed the grains twice as opposed to once, and this is called a double batch sparge. This results in a higher level of efficiency on average compared to a standard batch sparge. The first time you drain the mash, you receive the highest concentration of sugars in the wort, sometimes measuring quite high in specific gravity units. During the first sparge, the concentration is of course, significantly reduced.
Finally, on the second stage of batch sparging, and third, final drain, your concentration will be quite faint, which ensures that the first rinse pulled as much sugar out of those grains as possible.
At this point, you will have heated your water, mashed, sparged, (sparged again) and lugged your six gallons of Kolsch to the top of the stove for the final portion of the brew: The boil. The good news is that from here out, your process is almost exactly the same as with extract brewing, other than the fact that your malt extract is already dissolved into the tasty, pale wort.
As soon as the boil begins, wait a few minutes for the hot break to subside, add your 60 minute hop addition, and carry on through the rest of the brew and fermentation.
Remember: If all of this has melted your brain matter as much as it did to mine the first time I tried to all-grain brew, please feel free to ask any questions in the comments section, and I’ll do my best to get back to you with a clear answer.