Irish Moss, Protafloc, Copper Finings

How To Use Irish Moss, Protafloc and Copper Finings

Crystal clear beers rely on a few principles when brewing, copper finings such as Irish Moss or Protafloc / Protafloc are one of the aids that can help the home brewer make a bright, clear beer. What are they and how do they work? This is what we are going to look at in this article.

Irish Moss, Protafloc, Copper Finings

Copper Finings To Make A Clear Beer

For hundreds of years, brewers have looked for ways to clarify their beers. It’s only when you brew your own beer do you release it’s not always necessary to do so, however, many people won’t touch a beer unless it’s crystal clear let alone drink it. This is the result of many years of marketing telling us clear is good cloudy is bad. It is usually preferable to brew a beer with the end result being clear because, if you are anything like me, you’ll share your brews with friends who may not know a hazy beer isn’t a bad thing and it isn’t going to taste any different.

Throughout the brewing process, there are many things you can do, or ways to develop your recipes to ensure your beers have a minimal haze. I have written a bit about brewing clear beers here. One of the easiest things you can do that require the least effort is to add copper finings to the wort such as Irish moss or Protafloc towards the end of the boil.

What Is Irish Moss

Irish moss is actually a type of red seaweed called Carrageen. This type of seaweed is very common around the shores of Ireland, hence the name, but also grows around coastlines elsewhere in the North Atlantic.

It has a few properties that make it helpful to both cooks and brewers and has been used as a source of food in the belief it will strengthen and fortify malnourished individuals. It is used in the food industry as a stabiliser and thickener, used a lot in dairy products like yoghurt and ice cream to improve its consistency.

The reason it is so useful to us brewers is that when added to the wort at the end of the boil it helps to clear the beer. It is for this reason we call it a copper fining as it is added to the copper during the boil.

Irish Moss

Copper Finings – Irish Moss / Protafloc / Whirlfloc

Finings are used in a couple of ways, either in the fermented beer to help drop out suspended yeast or in the copper/kettle to clear suspended particles like haze-forming proteins and other debris.

Copper finings like Irish moss and Protafloc are important because help to coagulate these haze forming proteins together which makes them denser and therefore they drop out of suspension. If you don’t remove these haze forming proteins during the brewing process, it becomes difficult to do so after the boil without relying on processes such as filtration or auxiliary finings which is not possible or overkill for most home brewers.

Copper finings work based on the way particles in the beer are charged. At the pH of wort in the copper, around 5.0 – 5.5, the haze forming proteins in suspension are positively charged, at the same time, the Irish moss which is added toward the end of the boil has negatively charged molecules. The effect of this is particles that will induce haze in the beer are attracted together making them heavier and so they flocculate to the bottom of the kettle.

The Differences Between Irish Moss, Protafloc and Whirlfloc

All three finings Irish Moss, Protafloc and Whirlfloc work in the same way, there are just some subtle differences.

  • Irish moss is the raw seaweed carrageen or blend of certain types of seaweed. It comes dried and in various sizes from flakes, granules or powder.
  • Protafloc comes in either a tablet or granules and is an extract of carrageenan and other seaweed. As it is an extract it requires a smaller dose by weight as it’s more efficient. Tablets are also easier to divide with a 25 litre batch requiring just half a tablet. It works in exactly the same way as regular Irish moss.
  • Whirlfloc is pretty much exactly the same as Protafloc as far as I can tell although the dosage rate may be fractionally different, as in less than a gram per litre difference. Whirlfloc is sold as tablets and both Protafloc and whirlfloc fizz as they hit the wort to aid their dispersion, this is caused by bicarbonate of soda in the tablet reacting in the wort due to the pH.

Using Irish Moss, Protafloc and Whirlfloc

All the copper finings mentioned above are added around 10-15 minutes before the end of the boil, added too early and the efficiency of the product will begin to degrade.


Depending on what copper fining you are using you’ll need to adjust the dosage:

  • Irish moss is best rehydrated by just covering with water, the amount needed is around 1.25 – 4 grams per 25 litre batch. As you can see this is going to be quite difficult to measure even with micro scales. It is around a teaspoon full in most cases. Add the rehydrated Irish moss 10 minutes before the end of the boil.
  • Protafloc is used at a lower dosage as it is more efficient. The dose is around 0.3 – 0.5 milligrams per litre or 0.75 grams for a 25 litre batch. Tablets are made in 2 gram sizes so just under half a tablet is fine. Add directly to the wort 10 – 15 minutes before the end of the boil
  • Whirlfloc is pretty similar to Protafloc but used at 1 gram per 25 litre batch, half a tablet in the last 10 – 15 minutes is good.
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