Right then, let's talk about one of brewing's best-kept secrets that's been hiding in plain sight for centuries. Parti-gyle brewing is having a proper renaissance, and once you understand why, you'll wonder how you ever managed without it.
The Parti-Gyle Principle: Two Birds, One Stone
Here's the clever bit: you mash your grains as usual, run off the first wort, then give those same grains another go with fresh water. What you end up with is two completely different worts from the same grain bill—the first being stronger but smaller in volume, the second being weaker but more generous in quantity.
The magic really happens when you boil each wort separately. Suddenly you've got the freedom to create two entirely different beers: different hop profiles, different boil additions, different yeasts, different everything. It's like having two brew days rolled into one.
Why British Brewers Should Embrace This Tradition
Let's be honest—brewing a full 23-litre batch of Russian imperial stout or English barley wine can leave you with more strong beer than any reasonable person should attempt to drink. With parti-gyle brewing, you can still craft that special high-strength ale whilst producing a larger volume of something more suitable for regular consumption.
This approach has deep roots in British brewing tradition. Our ancestors understood that you could get maximum value from your grain whilst creating beers for different occasions. The stronger "keeping ale" for special times, and the "small beer" for daily refreshment—it's brewing wisdom that makes just as much sense today.
Working Through the Sums: It's Not as Scary as It Looks
Now, I know what you're thinking—maths and brewing don't always mix well after a pint or two. But stick with me because once you've got your head around the basic principles, it becomes rather straightforward.
A Real-World Example:Recently, I fancied brewing 2 gallons of American barley wine (OG 1.075) and 3.3 gallons of American pale ale (OG 1.035). Here's how the calculations pan out:
Gravity Units Calculation:
- Barley wine: 2.0 gallons × 75 gravity points = 150 GU
- Pale ale: 3.3 gallons × 35 gravity points = 115.5 GU
- Total requirement: 265.5 GU
Grain Bill Assessment:Using 10 lbs Maris Otter, 2.1 lbs Munich, 0.4 lbs crystal at 75% efficiency:
- Maris Otter contribution: 10 × 26 = 260 GU
- Munich contribution: 2.1 × 26 = 54.6 GU
- Crystal contribution: 0.4 × 25.5 = 10.2 GU
- Total potential: 324.8 GU
Plenty of headroom there, which means we're well positioned to hit our targets with room for the inevitable brew day variations.
Managing Brew Day Variables
The beauty of understanding gravity units is the flexibility it provides when things don't go exactly to plan. If your gravity's running low, simply extend the boil to concentrate the wort. Coming in too high? A careful addition of brewing liquor sorts that right out.
Just remember that any volume adjustments will affect your hop calculations. Nobody wants a barley wine that's bitter as wormwood or a pale ale with all the bite of a cup of tea.
Getting Started: Making Parti-Gyle Work in Your Brewery
The technique suits British brewing styles particularly well. Imagine creating both an English bitter and a barley wine from the same mash, or producing a mild alongside a robust porter. The possibilities are genuinely exciting for anyone who appreciates the full spectrum of beer styles.
We've been working on a detailed video guide that'll show you exactly how straightforward parti-gyle brewing can be in practice. Sometimes seeing the process in action clears up any lingering confusion about the methodology.
The historical context adds another layer of satisfaction—you're not just brewing two beers, you're connecting with centuries of British brewing tradition whilst maximising the potential of every grain in your mash tun.
Got questions about your parti-gyle calculations or want to share your own two-beer success stories? Drop us a line. We're always up for a good chat about brewing techniques that make the most of your ingredients and your time.
Grainfather Team
