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A10 Darkness - Imperial Organic Yeast
Ice Pack
In Stock
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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 0.37LBS
Community Q&A

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Why did you choose this?
MoreFlavor Store
because it makes delicious beer
Paul A on May 17, 2018
I have been hearing great things about this yeast, wanted to try it...
Phillip P on Feb 20, 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
Great results with other Imperial yeas products.
Timothy J. M on Feb 23, 2018

4.8 / 5.0
8 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Stars
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
I used this on my first oatmeal stout. With no starter this started fermenting within a few hours. I plan to use Imperial on my next brew to avoid the hassle of a starter.
February 7, 2018
4 months ago
Works very nice for stouts. Use a blowoff if you make a starter. It will blow up.
February 2, 2018
4 months ago
Seriously...Fermentation began (no starter) about 8 hours after I pitched. Very active for 3-4 days and settled out nicely. Used this on a high gravity hoppy imperial porter. nice fit.
Used again on an Oatmeal Stout with the same results.
January 25, 2018
4 months ago
good yeast, clean fermentation, but i dont get the same flavor profile as irish ale white labs does. but i still enjoy it.
January 23, 2018
4 months ago
It's pretty good!
This it thevBest yeast ever.
January 19, 2018
4 months ago
FAST FAST FAST! Great flavor as well.
Made a Coffee Oatmeal Stout and this yeast did not disappoint at all.

Temp: 68 with ramp to 70 after 3 days
OG: 1.078
FG: 1.020 (predicted was 1.023)

The krausen rose and fell. I almost missed it. Seriously the bulk of fermentation was done in 24 hours after it started. Have not made this same recipe so i cannot compare it to another, but i really really like this beer and will be using this yeast a lot more.

The ONLY negative is the can. LOVE the idea, but execution needs work. This is not the first imperial can i have opened and it isnt the first one that the tab broke off either. Bad design on the opening tab and the aluminum is just too weak. Then you are left trying to figure out what you are going to do now and not infect your yeast with anything (BTW, i used a clean sanitized flat head screw driver and it worked ok). That is the only reason for 4 stars. The yeast itself is awesome!
May 15, 2016
Good flocculation. I had much higher attenuation than what is advertised on IOY's website. Can't comment on taste of the brew yet as it will be conditioning for a few more weeks but samples were quite nice.

Mocha espresso imperial stout
Ferm temp: 68?F
OG: 1.094
FG: 1.009 after 18 days

The only reason I'm giving 4/5 stars is because of the poor design of the can packaging. Be sure to sanitize the lid before cracking it open as it will likely come into contact with the yeast. Also, do NOT shake the can as you would have with other popular yeast products...
December 14, 2015