Homebrewing Stack Exchange is a question and answer site for dedicated home brewers and serious enthusiasts. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a Oatmeal Stout recipe that calls for 4 tsp/ 1 gram of Irish moss powder. The LHBS had Irish moss, but I wouldn't call it a powder. They're small flat pieces maybe the size of half a grain of rice. Should I pulverize it in a morter and pestle? I would assume this would make it more efficient. Or just measure out a 1 gram and not worry.

If I use my (near impossible to sterilize) morter and pestle, is there any concern that the irish moss would not be sterile? Its going in the last 10 minutes of the boil.


share|improve this question
up vote 4 down vote accepted

Just add 1/4 tsp or 1g of what you have. Irish moss is a fining - it helps draw together proteins in the boil, and is primarily added to improve clarity, but it can also provide a finer head. It's not critical how much you use - some brewers use 1/4 tsp per 5 gallons, others 1 tsp.

The moss doesn't have to be sterile - anything added to the boil is quickly sanitized since most organisms cannot survive the heat. I would just make sure the pestle and mortar is clean - I use mine for crushing curry spices, and I wouldn't any hint of that in a beer!

share|improve this answer

Well if the recipe calls for a gram it shouldn't matter if its a powder or flakes, a gram is a gram. Irish moss is normally that flakey stuff you describe so I would just go with it either way as 4tsp or a gram. For what its worth, its not going to make a difference in a big dark Oatmeal Stout.

share|improve this answer

regular and powder are not the same. with powder you use way less than with regular.

share|improve this answer
While potentially helpful, this post is not responsive to the question, and should have been made as a comment. – Chino Brews Aug 5 '14 at 16:16

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.