So you’ve fine-tuned your recipe as we discussed in “Dialing in a Recipe,” and you just brewed exactly what you were hoping for. Celebrate that success, but understand that next time, it probably won’t turn out quite the same. For one thing, it can be hard to resist tinkering, but the truth is that, on our scale, relatively small differences in process can have a big effect down the line. For example, if you brew outside, variations in weather can impact how well your mash holds its temperature.
Inconsistency is what separates brewing enthusiasts from solid professional-grade brewers. Think about your favorite commercial beers that you’d have no problem recognizing. Would they be as good if they weren’t quite as dependable? Plenty of homebrewers will settle for each batch being a unique little snowflake as long as it’s tasty, but you worked hard to nail down that recipe and it shouldn’t be a one-off.
The good news is that, with some effort and attention, you can tighten your process and achieve some of the same predictability that you demand from an established brewery. The details of your recipe will get you to the right neighborhood, but reliably brewing the same beer takes control and active adaptation. Standard recipes list out the measured ingredients, starting and finishing gravities, and probably some basic process details such as mash steps and fermentation temperature. Brewing software such as BeerSmith or ProMash make that easier to manage, but let’s take a closer look at your process.
While there are all kinds of deeper details that you could track, three additional metrics will give you checkpoints to compare when you brew the same recipe again and provide control points to make on the fly adjustments.
Measure the Gravity at the Start of the Boil
Most brewers measure the original gravity (OG) after the boil, but it’s just as helpful to track the specific gravity at the start of your boil. This can provide an early warning signal that your beer is out of spec at a point where you can still do something about it. If the gravity is off from previous brew days, you can fix this before adding your hops. If you’re under the target, you can boil for extra time to concentrate the wort. If your gravity is too high, you can add water to dilute it. Make small tweaks and recheck until you get the gravity in line, then start your boil as normal. If you do have to bring it in line, you’re trading off final volume (either high or low) for greater consistency. Note though, that you’ll want to track the volume change because your hops may require an adjustment to keep the IBUs in line with your recipe.
Measure the Runoff During Your Sparge
You might be used to checking the gravity near the end of your sparge to make sure you’re not extracting tannins from grain husks, but you should also measure it at first runnings, then at each gallon afterward. Over time, this set of numbers exposes an extraction pattern that is specific to your equipment and process. This makes it easier to detect a hidden problem such as channeling in the mash tun. If your gravity drops off more steeply than usual between measurements, it could indicate that you have pockets of mash that aren’t getting rinsed. Rather than finding out later that your beer is short on fermentable sugars, you can recognize the problem and react by stirring up the mash and recirculating again.
Track the Volume Change During Your Boil
It’s an accepted rule of thumb that most homebrewers lose about a gallon or so of water during the boil, but the reality depends on a host of factors such as the geometry of the brew kettle, the relative humidity, and how vigorous the boil is. For the most part, these should remain fairly constant from batch to batch, but I’ve noticed deviations when the brew day is cold and damp. That’s why it can be helpful to track the volume at the start and end of the boil along with the ambient temperature and weather. Over time, you may notice a correlation, which would allow you to shift your start of boil gravity in order to hit your desired OG.
Additional Ideas
If you’re looking for other metrics to try, consider tracking the duration of your sparge. Variations here can have a big impact on your mash efficiency. Beyond metrics, you should also look at your general process for ways to improve consistency. For example, mash tuns are more stable with insulation, wind blocks can help isolate your brewing platform, and temperature-controlled fermentation keeps yeast in line.
Commercial brewers have automated systems and the experience of hundreds of batches to shake out the details. These metrics will help you develop the same familiarity with your equipment and brewing process so you won’t just make great beer, but you’ll make the great beer you planned, right from the start.