How effective will isinglass be to clear beer when I did not use Irish moss when I boiled. I know isinglass charged particles attach to the opposite charged particles produced by the Irish moss. My debate is whether to use cheap gelatin now, or to try out my isinglass. I have never fined before this.

4 Answers 4


Issinglass may be totally ineffective if you have too much colloidal haze which is a possible consequence of not using kettle finings. This paper from the MBAA states ...

For  isinglass  to  work  effectively,  brewing  literature  states 
that the beer needs to have a particle distribution in the range 
of  1  ×  10 6   particles  in  each  of  the  following  sizes:  <2,  
2–10, and >10  μ m. When there are too many or too few par-
ticles in these ranges, poor clarity, poor settling, or higher beer 
losses can result (13,16). 
When  there  are  too  many  particles  in  the  beer,  the  use  of 
auxiliary finings can be helpful to reduce the amount of parti-
cles  to  the  optimum  range  stated  above.  Kettle  finings  are 
added  to  the  kettle,  and  auxiliary  finings  are  typically  added 
prior to isinglass in the cellar, or they can be used further up-
stream in the process.

What's more isinglass is difficult to prepare and difficult to store e.g. Murphy and Sons recommend ...

  • At no time during mixing or storage should the temperature be 
    allowed to exceed 14° C (57° F) or fall below 10° C (50° F)

Gelatin is a better choice for homebrewers, although I prefer PolyClar.

  • 1
    Interesting paper. It basically says isinglass purchased at a LHBS or shipped would only function as gelitan with little fining abilities since it's denatured above 59°F and turns to gelitan. I've never seen it in the refridgerated sections. If correct, this could be why homebrewers rarely get fantastic results. Sound like most applications are just utilizing it as a less effective form of gelitan. Mar 29, 2018 at 15:47

Isinglass will work just as well without Irish Moss in the boil.

As far as Irish Moss and Isinglass working together they are really for two different things.

Irish Moss is intended to flucculate and drop out hop and grain matter in your cold break. Then this trub is left behind in the kettle/whirlpool and not transfered to the fermenter.

Isinglass is best at fining out yeast after fermentation.

Personally I use neither. Cold crash is all that's really needed, gelatin if I want it rushed.


I used Isinglass once, it came with a wine kit and there was no Irish moss involved, but another product that I can't remember the name (perhaps chitosane?). It should work on its own, wikipedia mentions that :

Isinglass is sometimes used with an auxiliary fining, which further accelerates the process of sedimentation.

Isinglass should precipitate yeast cells effectively, but Irish moss seems to coagulate proteins. They complement each other from what I understand.

  • For the difference (or not) between gelatin and isinglass see here.
  • Gelatin is easier to use than isinglass.
  • There is no need to use Irish moss before using gelatin or isinglass, they work independent of each other

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