Author: Marshall Schott
We’ve all been there– the wort has been produced and added to the kettle, it’s time to commence boiling and add hops to the wort, back is turned to help a kid or grab a beer or watch TV, when suddenly molten hot stickiness erupts out of the kettle, plastering itself to anything it touches, singeing skin, and causing the significant other to question the merits of this obviously messy hobby.
Boilovers are the bane of many a homebrewer’s existence, one I’ve seen people attempt to deal with in some pretty creative, sometimes humorous, ways, many of which I’ve tried. While some brewers swear by spraying water over the wort at first sign of hot break, I’ve tried this and it didn’t work very well. One method that worked better was blowing the wort as it started to foam, but this always led to me being very lightheaded, which increased my risk of injury… plus, it just looked weird. What I hated about both of these options is they required me to be far more attentive than I’d prefer while brewing, meaning I had to sacrifice clean-up (drinking) time to monitor the boil. No thanks.
A few years back, I started poking around on the web, searching for ways commercial breweries deal with this problem. This led me to a thread on a pro brewer forum (I forget which one) where a dude was talking about how he hadn’t experienced a boilover since he started using an “anti-foam agent.” My interest was piqued so I went to and I searched MoreBeer.com for anti-foam. I landed on the page for FermCap-S, which claimed to eliminate the risk of boilovers. Interested and surprised that a vial of this stuff only cost $4, I threw it in my shopping cart with enough other stuff to qualify for free shipping.
While making a starter the following week for an upcoming brew day, I had the idea to add some of this milky substance to see if it really worked. Did it ever! I boiled 3L of wort in a 5L flask without a single drop escaping, barely any foam forming at all.
The following weekend, I made a 12 gallon batch with a pre-boil volume of 13.5 using my 14 gallon kettle. Per the instructions on the bottle, I added 26 drops of FermCap-S and crossed my fingers.
The boil started and the hot break just seemed to magically disappear. I was ecstatic, I was amazed… I was worried. As the boil proceeded, I started wondering what the hell I just put into my wort and how it might effect the finished beer. Would it have an impact on fermentation, flavor, head retention? Was it going to give me cancer?!
The finished beer fermented as usual and came out great, no noticeable degradation in foam or flavor. Still, I was curious, so I did some research and discovered a few interesting things. First, FermCap-S works by decreasing the surface tension of the boiling wort, meaning any bubbles created during the boil immediately burst. This sounded oddly familiar. As I kept digging, I found that this potion was nothing more than polydimethylsiloxane, a silicone based liquid remarkably similar to another anti-foaming agent commonly referred to as Gas-X. Yep, the stuff used to reduce bubbles in my gut is basically the same stuff used to do the same in my beer. There was some stuff about how the FDA recommended filtering beers that used FermCap-S, followed by a plethora of opinions contending it readily drops out of beer naturally and, even if it didn’t, would cause no physical harm given the amounts used. I also read some opinions suggesting use of FermCap-S actually improves head retention due to… well… something about proteins not breaking down.
It’s been 3 years since I started using FermCap-S, it goes into every starter and batch of beer I make as a matter of course. Was it worth the cost? Well, I make quite a bit of beer and I’m barely 3/4 the way through my first 1 oz bottle of the stuff. I realized the 2 drops per gallon recommendation is a tad overboard and now use 1 drop per starter, 3 drops per 5.5 gallon batch, and 5 drops per 11 gallon batch. Boilovers are a thing of the past in my brewery. Can I get a hallelujah?!
I know some folks who also like to use FermCap-S in their fermentor, claiming it helps keep blowoffs at bay. In my experience, it doesn’t work nearly as well as in the boil, though a couple drops at high krausen does seem to have a moderate impact. I’d imagine the results might be different for those who ferment in buckets, as dropping FermCap-S in multiple spots would potentially be more effective.
| THE VERDICT |
If you make beer at home, you should have FermCap-S in your tool bag, plain and simple. It’s cheap, effective as hell, and lasts a long time. Whenever I see someone spraying water or blowing on their boiling wort, my first thought is that they likely haven’t heard of this amazing product, so I tell them about it, touting it more than perhaps any other item in my brewery.
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28 thoughts on “Product Review | FermCap-S Foam Control”
good to heat it works as advertised. it was already in my wishlist for my next buy, guess it will stay there.
This is probably one of my best finds as a homebrewer. It is amazing how well it works. I’ll never not have some on hand when I’m brewing. I’m amazed 100% of homebrewers don’t use this stuff.
Amen. I experience awe every time I use, even after hundreds of uses.
I am interested in how it works during fermentation. I have used to eliminate boil over and agree that it works great. I have not paid attention to how it effects fermentation. I want to push the volume limits of my fermenter a bit and reduce the danger of loss too much to blow off. So, do I need to add more defoamer to my fermenter? Or will the defoamer used during the boil carry over?
I typically add 2 drops/gal for my primary ferment (in a carboy) and haven’t had blowoff in who knows how long. The secret, I think, is waiting a few hours after pitching to add the FermCap, that way the yeast are producing enough activity to mix it up and keep it on the surface.
I used it for the first time on my last brew, 13gals of RIS. I added 2 drops/ gal and it came to a nice boil in my keggle. I then added my hop addition and everything went to hell. Beer everywhere with the first touch of hops. Now that keggle was full, but nowhere near your picture. I plan on trying it again, but as of now, I’m not sold.
Oh no! I have to laugh just a bit because I can relate. Hops, particularly pelleted hops, create nucleation points when added to boiling wort, which leads to crazy eruption that dissipates quickly. The best way I’ve found to deal with this is to add the hops slowly and spread them around the wort, don’t just pour them all in at once or else….
I just put a few hop pellets in the wort before it comes to boil, works just as well for me without the silicone in my beer.
Silicone? Perhaps simethicone?
I believe the former is in the latter.
Interessting, but what is actually inside? Which chemicals? Nothing is noted on morebeer.com or on the bottle. I usually want to know what I put in my beer before I do so.
This seems to be interessting:
http://homebrew.stackexchange.com/questions/3661/what-is-fermcap-s-and-what-does-it-do
http://www.homebrewtalk.com/f12/fermcap-s-alternative-322227/
There are multiple places online which note that the FDA says it is necesarry to filter FermCapS before consuming the beer. Seemingly FermCapAT is an alternative which needs no filtering.
It’s basically just baby Gas-X, and I trust the tiny amount I use falls out of solution by the time the beer is ready to drink anyway, especially when using gelatin.
Consider all the great beer brewed without this additive, it’s totally unnecessary.
Beer… is unnecessary. Technically.
So this was on my shopping list and I spaced it out. Subsequently I had my worst boil over ever in my first (5.5 gallon) batch in my new 14 gallon brew kettle. I didn’t think that would even be possible, given all that headspace.
Needless to say, it’s on the top of my shopping list for next brew day. (And I’m trying your lil’ slack recipe, so wish me luck)
Oh man, what a bummer! FermCap is amazing stuff, you’ll never regret that purchase. And Lil’ Slack ain’t too shabby either. Cheers!
I’ve discovered that that Morebeer 14 gallon kettle *will* fit in my dishwasher. Which makes the boil over less painful. And boy that SD super yeast is one active fermenter at 68-70 degrees. Luckily it didn’t blow the airlock into the ceiling
Curious about others experiences. I picked up the 5-star defoamer recently since that’s all my LHBS sells. I didn’t notice much difference in my boil. Not sure if I added it at the wrong time (I put 5 drops in right before I started the burner. Not sure if the 5-star product is just not as good as fermcap-s or if it’s operator error. I’m assuming I screwed it up since both products seem to be silicone based, but who knows. The info I’ve found when scrolling forums has been mixed and not helpful on this one.
I’ve never used the other stuff, but with FermCap, I add it before the boil even starts and it works great.
Hmm, Next batch I’ll try adding it at maybe 200 degrees just before it boils and see if that helps. If not, i guess I’ll just have to order some fermcap-s online instead.
I am going to get a bottle of the stuff. Curious, what is the height of that counter your burner is on?
I had a bottle of this stuff for a few years now. Used it in my fermenter without much success. Was just in the process of babysitting my BK when I remembered reading your review. Ran back to my beer room, grabbed it up, ran back just in time to see the foam reaching the edge of my kettle. Added 5 drops in various spots in the foam and watched it drop down like a damn magic trick!! Gonna get another bottle of this stuff!! Thanks for the review, and keep up the awesome experiments!
When using it for a starter, does putting that one drop in the pot to prevent boilover also help prevent krausen build up in the flask, or would i need to add another drop in the flask as well?
It appears to help sometimes with some strains, but not always.
I’ve been using this fermcap S for sometime now, afraid of whats in it that’s harmful I trust Marshall & his research, This read has put me at ease…coincidentally in an attempt to be as safe as possible I don’t use 2 drop per gallon either, I use a total of 3 drops in the boil at about 200*, never had a boil over or had a carboy explode. So do I put a drop in my next burrito is the question?
Here is some interesting information from the Danish Ministry of theEnvironment, regarding polydimethylsiloxane:
https://www2.mst.dk/udgiv/publications/2005/87-7614-756-8/pdf/87-7614-757-6.pdf
It appears that the only information (in 2005 when it was released) regarding human toxicity was sourced from the trade group representing the industry. There is also mention of possible links to endocrine disruption, and a tenuous link to possible carcinogeneity.
So, this brings up the hotly-debated: ‘is no evidence of adverse health effects the same as being not bad for you?’. Not to mention: ‘the stuff is everywhere around us anyways, so why fight it?’
Might be better to just throw a pat of butter in our wort as an anti-foaming agent, like with making jam. Or just watch it carefully and stir it down as needed. Some to think of it, the butter vs. polydimethylsiloxane face-off might make for a good xBmt.
I know of a couple brewers who add the slightest bit of olive oil. like a drop from a toothpick. for yeast health. or so they say.
I was going to try some but since I started first wort hopping I’ve never had a foaming issue.