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This is a shill question for Mark Taylor. I stumbled on his great tip about keeping a spray bottle on hand to prevent boil-overs while looking for advice on yeast re-use. The spray bottle worked amazingly well. Ample room in the boil pot is pretty obvious. What other strategies are there?

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13 Answers 13

up vote 3 down vote accepted

I've used FermCap in the last couple of batches. Seems to work great for preventing that initial boilover. It still gets foamy, but the foam dissipates much more quickly. Excellent in starters on the stove top as well. No noticeable effect in the finished beer. No problems with head retention, etc.

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If you don't have a spray bottle or hose nearby, you can stir the wort with a big spoon or paddle and that will break up the foam. Just be careful not to burn yourself!

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Giant Pot

I use a 20 gallon pot for a typical 12.5 gallon wort boil.

Sometimes I have a spray bottle

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I keep a very close eye on the foam level during the first 10 minutes of the boil and am very ready to kill the heat if need be. Recently I've been boiling with my pot about 2" from the rim at the start of the boil and haven't boiled over... yet. Brewing on a gas range (as opposed to electric) really provides for a lot of control over the heat input. With gas, when you kill the heat, it's killed, unlike an electric coil stove where you kill the heat and it starts to cool off.

When adding hops, I drop in one or two to test the water - er, wort - before going all-in. Hops provide a lot of nucleation sites, so adding them quickly could cause there to be a ton of foam when there was no foam seconds earlier.

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Similar to the spray bottle...I keep a glass of cool water nearby. If the foam starts rising I dump a little in. Settles things down nicely.

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Adding a few hops before the boil starts will control the foam up. I add 3-6 pellets from my first bittering addition. I don't remember the science behind it (explained on Basic Brewing Radio), but something with the oils of the hops helps to reduce the foam. Also blowing on it......

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+1 for blowing on it. I did this in a panic once and was amazed that it worked. Don't know if it's a function of my pot shape (it's wider than it is tall) but all it takes is blowing on it for 2-3 seconds and it's under control. When I had a smaller pot I could snatch it off the heat fairly easily, but now I'm doing full-volume boils in a 10G pot so it'd be a bit more challenging. – TMN Dec 17 '12 at 17:56
I have also had luck with blowing. My pot is taller than wide. I am thinking of trying to automate the boil with an accoustic distance measure that would trigger a hair-drier (on cold setting), all powered by a RPi – CHsurfer Jun 25 '15 at 12:31

Fermcap S is far and away the best solution. Use as directed during the boil. You can also use it in the fermenter to prevent a large krausen from overwhelming your airlock, but you will need to adjust your IBU's as it will reduce hop utilization during fermentation.

You can also add a drop or two to your starters to prevent boil overs when preparing them.

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I now use fermcap, but I found a little 5 inch fan directed right at the surface works great.

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I brew on my stove which is right next to a window. I open the window, turn on the vent fan, and when boilover is imminent, I'll blow on the foam, and that reduces the foam quite quickly. Granted I've only done this with extract and specialty grain, so it may not work in all-grain, but I'd recommend it for a try.

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I just pick the pot up off the stove if a boil-over seems imminent. Gas or electric, that immediately stops any boil. If you're not in the vicinity to notice a pending boil-over, then I don't know what you can do beyond buying a bigger pot or using FermCap.

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This could be extraordinarily dangerous for anyone doing anything more than a 2-3 gallon boil, and not advisable for even those. – Rich Armstrong May 9 '12 at 21:06
Really? I regularly do this for 3-4 gallon boils in a 5.5 gallon pot. Any rising froth immediately recedes once heat is not being applied, so it's not going to get on my hands. If it seems too heavy, one can set it down on the adjacent burner. – alex.jordan May 10 '12 at 0:12
My concern with lifting my 20 gallon pot when it's full to 13 gallons is the integrity of the handles and their attachment to the pot. If one should break, I'd have boiling liquid everywhere and probably some severe burns. As pots get smaller, this is less of a concern. – Dustin Rasener May 10 '12 at 2:51

The first defense for me is the spray bottle but frankly the only times I've had boil-overs is when I'm not paying attention. So, first on my list of boil over remedies is paying attention as the boil nears 212f.

mark Beer Diary...

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I have an oscillating fan that I put on low that blows right on my keggle. Keeps the foam down, but you will end up with more loss of volume, so be prepared for that with some distilled water to top off with if needed.

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I find that a fan pointed at my brew helps prevent boiling. Similar to the gentlemen that blows on his brew, but this way you don't have to worry about lung capacity. One caveat: I'm pretty sure this will increase your boiloff rate, so you'll want to compensate accordingly.

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