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A10 Darkness - Imperial Organic Yeast

A10 Darkness - Imperial Organic Yeast

In Stock
60 day no hassle return policy. Details

A10 Darkness is exemplary for use in stouts, porters, browns, as wells as amber ales. Its unique character pairs perfectly with roasted and caramel malts. Due to it’s alcohol tolerant nature, this strain will also work well in high gravity beers.

  • Temp: 62-72°F, 17-22°C
  • Flocculation: Medium
  • Attenuation: 71-75%
  • Cell Count: 200 Billion

White Labs Equivalent: Irish Ale – WLP004
Wyeast Equivalent: Irish – WY1084

Usage Instructions:
  • ​Store refrigerated until ready to pitch
  • Shake and kneed pouch to homogenize slurry
  • Sanitize the sealed pouch
  • Open and pitch entire contents into well-aerated wort

Please Note: For best results we Always recommend ordering an Ice Pack with your liquid yeast. Ice Packs can be found below in the "You might Also Need" section.


Item # IYA10
Shipping Eligible for Free Shipping Program
Availability California - In Stock
Pennsylvania - In Stock
Weight 0.37 LBS
Community Q&A

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Browse 2 questions Browse 2 questions and 33 answers
Why did you choose this?
MoreFlavor Store
Brewing big high gravity imperial stouts
Quinn H on Mar 25, 2020
Brewing company 30 gallons of beer
Brad M on Mar 5, 2020
Brewing big high gravity imperial stouts
Quinn H on Mar 25, 2020
For Stout
Jaime E on Mar 17, 2020
Brewing company 30 gallons of beer
Brad M on Mar 5, 2020
PAUL L on Jan 27, 2020
Win P on Jan 15, 2020
seemed like the best selection
Jim H on Dec 27, 2019
can i go now
C H on Nov 23, 2019
I need to brew some dark beers
Michael B on Oct 19, 2019
Cause it's the best
Jason T on Sep 11, 2019
Guinness sourced yeast for my stout pleasure.
John H on Aug 28, 2019
excellent yeast
Ron C on Jul 4, 2019
Made a very good Guinness clone
chris l on Apr 9, 2019
Trying out for a blonde stout recipe being brewed this weekend.
Adam S on Apr 2, 2019
Great performance
Oscar A on Mar 7, 2019
The reviews were great.
chris l on Mar 2, 2019
Imperial yeast is my new favorite
WILLIAM C on Jan 7, 2019
200 billion cells! This brand of yeast is awesome!!
JAMES K on Dec 12, 2018
first time using this yeast
Donnie F on Nov 17, 2018
Trying this year out for my Porter
Scott B on Oct 30, 2018
Very reliable yeast for porters.
Ronald W on Oct 17, 2018
I love all Imperial Organic Yeast. It kicks off super quick and it rips through fermentation.
Alexander S on Sep 14, 2018
Milk stout
Ralph Sprandel on Sep 5, 2018
Seems to go with the recipe
donald w on Aug 17, 2018
It's not available at my LHBS.
karl h on Aug 15, 2018
Friend recommendation plus heard about it on Brulosophy podcast
David N on Aug 9, 2018
brewing a stout
Kevin D on Aug 2, 2018
like it
A.J. B on Jul 30, 2018
I have used this for a chocolate stout in the past. Fantastic!
Gregory F on Jun 6, 2018
Brewing a stout
Luis A on May 28, 2018
because it makes delicious beer
Paul A on May 17, 2018
Great results with other Imperial yeas products.
Timothy J. M on Feb 23, 2018
I have been hearing great things about this yeast, wanted to try it...
Phillip P on Feb 20, 2018
For Stout
Jaime E on Mar 17, 2020
PAUL L on Jan 27, 2020
Should I be worried if my yeast pack is swollen?
Mariano Sanchez on Aug 28, 2019
BEST ANSWER: if the pack was packaged at sea level and you live at a higher altitude, any air trapped in the package will expand. If you had the yeast shipped without an ice pack, the yeast likely came to life in transit and are creating carbon dioxide. Put it is the fridge ASAP and use soon! Take care as you open the package to avoid a spraying of the contents all over your work area. If there is no leak in the package, you should be good to go.

4.6 / 5.0
17 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
Active fermentation started in 2 hours, slowed in 3 days, and an occasional bubble at 3 weeks. Hit final gravity at 3 weeks also. This required a blow off tube for the first 4 days also.
Worst cleared nicely!
March 26, 2020
3 weeks ago
Perfect in Honey Porter
Pitched directly in 5 Gal 1.08 OG Honey Porter, fermentation started within 6 hours, very nice flavor
March 18, 2020
3 weeks ago
Awesome little microorganisms!
Great active yeast. Even better flavor.
Very Active in Imperial Stout.  Will need blow off containment.
Very Active in Imperial Stout.  Will need blow off containment.
January 10, 2020
3 months ago
Great yeast
This strain is awesome
February 15, 2019
1 year ago
The yeast was inactive, no fermentation at all. I had to use another brand. This was very unfortunate as I was looking forward to trying it
November 13, 2018
1 year ago
Response from MoreFlavor
Hello Kevin - This is quite the anomaly, we use Imperial a lot with great success. Please give us a call at 1-800-600-0033 or email us at so that we can assist you. We are here to help. Cheers!
November 16, 2018
Zach R Staff
Used a starter. Low fermentation temperature made a very clean and delicious porter.
October 5, 2018
over 2 years ago
Great flavor but higher attenuation than specified
Made a 1/2-BBL batch of porter wort @ 1.062 OG.. Divided into three 5-gal fermenters, each with a different brand of yeast (Imperial, Giga, Mangrove). Each yeast chosen was "medium" attenuation, with theoretical finish of 1.018 (based on mash temps and attenuation). As predicted, one yeast stopped at 1.020, the other at 1.018. But the Imperial went down to 1.009, which would be considered high attenuation. All 3 fermenters were identical, side-by-side, and same duration in secondary.

I would rate 3 stars for the average home brewer, but I'll give it a 4 star since the flavor was great and I can compensate for the attenuation factor if I ever use it again.
July 6, 2018
over 2 years ago
It is a monster of a yeast, loved it
User submitted image
Added Jun 10, 2018
June 10, 2018
1 year ago
Rock Solid
I pitched this into a dry irish stout that will later have some cold brew coffee added. It went from 1.046 to 1.011 in less than 3 days and dropped clear by day 5 (fermented at 67). Crazy fast fermentation and super clear beer really quickly. I am super impressed and will def use this again!
June 4, 2018
1 year ago
Great Fermenter
Used it both for a robust porter and an imperial stout (11% ABV). In the robust porter it had a good fermentation but I used it without a starter. For the imperial stout I bumped it up twice in a starter and it fermented like hell in the primary. (Lost about 0.75 gal of beer from the blowoff being so strong - started with 5.5gal in a 6.5gal carboy) Flavor is generally clean, dry, with a little English character. Will definitely use again.
User submitted image
Added Apr 23, 2018
April 23, 2018