Saison Yeast - Airlock vs. Open Ferment - Does it prevent "stall"

drew's picture

These days it seems like if you want to open a craft brewery you need 3 different styles of IPA, a few DIPAs for people to pound, a couple of bourbon barrel something or others, some sour projects to charge ridiculous amounts of money for and then my favorite style - saison. But there's a problem - the two primary strains people use Wyeast 3724 Belgian Saison and White Labs WLP565 Belgian Saison I both suffer from quirky fermentations. Namely, you pitch them and they take off like gang busters and then about 36-72 hours in they "die out". You get excited, "that was a quick fermentation!", and check your gravity (because you're a wise brewer) only to discover your 1.055 Saison has only dropped to 1.030 and isn't budging. You're "stalled" The usual way of dealing with this stall is to crank up the heat - hit the 80's, heck hit the 90's. Rouse the yeast and sit back and wait - fingers crossed. If that doesn't work within two weeks, hit it with a reliable fermenter like WLP001/Wyeast 1056 to finish off the ferment and hope you've got sufficient "saison" character during the initial ferment. Some crazy people even advocate crazy things like pitching the wort while still in the upper 70's/lower 80's. But, as I started writing about saisons, I got told by some very smart folks at our favorite yeast libraries that the real trick was back pressure - aka the little bit of pressure increase seen in fermenting wort due to trapped CO2. Could the answer then be to do an open ferment? Will that keep the yeast humming along? Turns out, I was already doing it since I ferment in kegs and just crack the pressure relief valve. I suspect that dissolved CO2 in the wort also plays a role, but that's not the real question - the real question is can removing the airlock and subbing some foil really keep the stall at bay? We'll be working from my Guide to Saisons and Saison Yeasts.


Proposed By: 


Does using an open fermentation technique avoid the fermentation stall and produce a noticeably different beer that typical closed fermentation techniques used by modern brewers.


Open fermentation practices do avoid the "saison stall" and produce a different beer than closed fermentation

Brewing Sessions Needed: 



Special Equipment/Process: 

Fermentation temperature measuring equipment. The ability to chill the wort to 64F.

Special Observations: 

This particular test is less about the final triangle test and more about the observations of the fermentation. Record and report the type of vessels used. To that end, experimenters are requested to track ambient temperature, fermentation temperatures and apparent fermentation activity in both vessels on a daily basis. Record how long it took each vessel to finish, final gravities and do a comparison gravity when one vessel completes if the other is still working or stalled.

Experimental Procedure: 

  1. Read Drew's Saison Guide
  2. Brew enough Saison Experimentale to split evenly between two fermenters (e.g. brew 5 gallons and split evenly into 2.5 gallons for fermentation). Record the Original Gravity.
  3. Chill the wort to 64F before pitching equal amounts of either WLP565 or Wyeast 3724 (Please tell Drew which you're doing) into both vessels
  4. For the first vessel, add an airlock or blow-off tube as you might normally. For the second vessel, cover the airlock opening with sanitized aluminum foil.
  5. Ferment both batches in the same space and under the same conditions (65F), especially temperature. Match the fermenters and other equipment. Record the daily fermentation temps, activity and ambient temperature if not in a temperature controlled space (fridge, freezer, etc).
  6. After 3 days of fermentation, let the fermentation temps rise naturally for the rest of fermentation, continue recording temps and observations.
  7. After visible fermentation subsides (aka the krausen falls), record the length of fermentation and the gravities. Let the beers continue to terminal gravity (1.004-1.008), record the length of fermentation and the final gravities.
  8. Package the two beers in exactly the same fashion. (Bottle primed with sugar, kegs and force carbonated, etc) - Record packaging methodology
  9. Perform a triangle test and record the results
  10. Ask the testers for their observations on the samples. DO NOT Reveal the Difference between the samples
  11. Discuss the results and record any further observations

Further Exploration Paths: 

What about other Saison strains? What happens if the two "core" Saison strains are pitched together. (Theory being they are two strains independently isolated from Dupont) What happens if we don't follow Drew's persnickety methodology and follow a more traditional hot pitch route?
Klickitat Jim
Klickitat Jim's picture
I'll report on this one fo

I'll report on this one fo sho. But it will be a while. Probably about late May before the weather will cooperate. Last year I tried the rapid rise to 90F trick. In 6 weeks I was able to reach 1.010... finally gave up and went full Logsdon, pitched Brett L. This year I'm pitching a high krausen starter and trying the foil trick.

mikebob's picture
accidental scientist!

It appears I may have accidentally done this experiment already. I brewed a saison in mid December o.g. 1.055. It was a 7 gallon batch and 5 gallons went into a carboy with an airlock the other 2 went into 1 gallon jars covered by foil. I pitched a saison yeast propagated from an ommegang Hennepin bottle. Fermentation shot off like a rocket! The krausen almost blew out the airlock and hit the foil on the 1 gallon jars. Fermentation temp was a steady 67' until about a week ago when i chilled it to 38'.And it dried out to 1.010 in about three weeks in all three fermenters. My point is, do you think this happy coincidence would yield usable data so long I package all three in the same manner and do a blind triangle?

JamesK's picture
Rise naturally

My house is cold enough that I often need to heat the wort to reliably ferment higher than 64. Rather than letting tems "rise naturally", should I plug in something like 70? 75?

Also, I don't see any instructions to take gravity measurements along the way, which seems relevant to the topic. Should we add a day 7 gravity checkpoint?

drew's picture
I'll add a check poiint for

I'll add a check poiint for measure at krausen fall.

CA_Mouse's picture
Do we have a recipe for this

Do we have a recipe for this one?



CA_Mouse's picture
Found it! I must be getting

Found it! I must be getting old... or the meds have kicked into overtime! LOL


drew's picture
<thumbs up>

<thumbs up>

When do you want this

When do you want this experiment done by for results?

drew's picture

Are due by 6/29 for the show!

JamesK's picture
My homebrew club meeting has

My homebrew club meeting has been pushed back to the 30th.  Will getting the results the following morning be soon enough to be useful?

My non-tasting results are here, fwiw:


drew's picture
Yes, you'll be fine! Don't

Yes, you'll be fine! Don't forget to submit resutls as soon as you can! Thank you!

jengum's picture
Stainless vessel

I could brew this on Friday, the 27th. I'd like to use stainless conicals, but that means not watching for krausen fall. Any issues with this? Otherwise, I can follow the checklist. Thanks!


Portland, OR, USA

Making stuff - adult bevs, charcuterie, music

Mostly brewing Belgian Triple/pale inspired

drew's picture
No problem from my point of

No problem from my point of view. Just do your best to observe what's happening in primary.

Found Out Too Late but I Have Early Results!


I found out about this experiment too late to follow directions, but I've got some results/knowledge to share.

I'd heard about using an open fermentation or a semi-open fermentation to prevent that bastard 3724 from stalling. I also had it on good word from a fellow brewer of exceptional skill that his method  would force 3724 to finish out even after it stalled.

And so the process:

Grain Bill: 95% Best Malz Pils, 5% Best Malz Wheat Malt

Mash: 148 F

OG: 1.052

1.25 liter starter

Glass carboy, bung with thermo, blow off hose into a jar of sanitizer.

Pitch @ 70 and let it free rise for 2 days. Raise 5 degrees every day until at 90. Go to 95 if you're feeling dangerous. Wait.

Once I hit 80 degrees and had some good off gassing occuring I figured it was safe to assume I had a blanket of C02 to protect from oxidation if I opened it up.

So... I opened it up. I pulled the hose out of the sanitizer, rested it on the side of the fementer and for the next five degrees I let things go semi-open. Once it was at 85, I closed it up again (hose back in sanitizer). Krausen got bigger still. Once at 90 i've been doing an open for one day and a closed for another day. On/Off Days basically. Been at it for about 9 days now since pitching and the krausen dropped today. Checked gravity and I'm at 1.018 so well past the typical 1.035ish stall out. If I remember, I'll post once I hit terminal which should be around 1.008 if my mash works out.

So yeah, obviously YMMV, but this yeast has always been a real fucker for me no matter the temperature schedule. Not a full believer yet in open ferm, but I'm starting to think about actually making saisons with this yeast again instead of cursing its name every chance I get.


drew's picture
Very cool - glad to see that

Very cool - glad to see that the technique my have worked for you!

ejpejp77's picture
Late to the game, results as advertised

Late to the game on this experiment (brewed on 6/26) but I ran it anyway.  I used 3724.  One smack pack per 3 gal fermenter, smacked 3 days prior. The deviations from the script were as follows.  The mash temp control was a bit off.  It drifted from 150-144 over 90 min. Substituted D45 Belgian candy syrup for cane sugar.  OG came in at 1.050.  Pitched at 73F (ambient).

After five days, both the foil and airlock fermenters went to full kruesen, settled and were both measured at 1.024 and 1.024. They looked identical and seemed to fit the description of the classic stall.  Five days later.  The one with the foil came in at 1.022 while the other was still at 1.024.  I was wondering if the fermenter with foil would pull away from the one with the airlock. Lo and behold, nine days after that (last Fri) the fermenter with the foil was at 1.012 and one with the airlock is at 1.018.  Fermentation temperture when from 73F at pitch time to 70F over the course of 5 days and have been 69.5-70F ever since.

Despite my deviations, the results appear to be behaving as described in the podcast.

It's a good bet that if I'm patient they will both finish and turn out tasting the same as Marshall observed.  I expect the one with the foil will finish sooner.

With that in mind, rather than duplicate those results, I think I'm going to get extra mileage off this experiement and finish the fermentation of the airlock batch at a higher temperature (85F) and check to see if it catches up to the foil fermeter and in the end if there is a flavor difference.  I got a DIY fermentation chamber from one of these "crazy" guys who claimed to have won all kinds of BJCP judged competitions and swears by stressing the crap of Saison yeast by running up the fermentation temperature.

We'll see.


- Eric

Air lock

When to put air lock on , in fridge at 64 .Been fermenting for 3 days with just foil on top. Was wondering ,take out of fridge then put on airlock or still let it ride on counter at 68.Then I will put outside in garage for a couple weeks ,before checking gravity. New to this open fermenting dont want to screw up. Did your pumpkin saison

PharmBrewer's picture
Fermentation Tests for Starter and Air Access Experiments

While this was not a Saison brew, don't know if you saw these results from a past Braukasier experiment :)


"Chance favors the prepared mind" - Blaise Pascal