Are you sure it was used correctly? You add the drops as the foam starts to rise in the kettle. It knocks it right out and the foam doesn’t reappear.
I’m sure it is the same technique for fermenters and krausen.
Actually, it is possible to have your boil turned up so high that not even Fermcap can help. If you use a little caution, it works great. If you assume it makes it so you absolutely can’t boil over, you’ll be in trouble.
I have a false bottom in the kettle. I use freely roaming hops (no bags to fence them in), and the fermcap-s has been no problem.
With pellets or whole leaf? That may be the difference?
Jeez! I’ve never had a problem with it failing in the boil. If someone is boiling that hard- then it’s an additional issue. AFAIK that isn’t great for the end product.
That is the very device I use, and clogged up.
I use a false bottom in my boiler as well, these days mainly with pellet hops…no problems at all and no schmutz going into the fermenter either…
So free floating pellets? If so what kind of kettle do u have and who made the false bottom
?
I’ve not tried pellets only in years; I recently switched to a false bottom from a screen, but I’ve been skirred to try pellets not in a bag because of the horror stories.
I stock mostly whole leaf but if I could use pellets without bags that would be sweet!
I’ve always used 1 oz leaf for insurance. Works very well. Maybe one day I’ll try all pellet. Or maybe not. 
hopfenundmalz and Professor: which FBs are you guys using? I’m using an ABT wrapped in SS screen suspended to give me the extra straining area.
I can use around 8 oz max pellet hops without problems for 10 gallons. Over that I should have a dose of whole hops in there to help keep some of the spooge above the false bottom. I can use over a pound of whole hops with no worries.
Right now the boil kettle has a Sabco false bottom, SS screens with round holes. The mash uses a pico-brewing false bottom, slotted copper.
It’s also worth noting that if you’re having boilover problems you can turn the heat off and let the wort sit for approx 10 minutes right as it starts brushing 212F. That gives the hot break more time to coagulate and sink, keeping it from causing boilover foam. I used to do that when I had a 7 gal boil in my 8 gal pot, never a real boilover problem as long as I was paying attention. As soon as the temp hits 211 or so, I’d turn the heat off, have a beer, and turn it back on again. I have since started using Fermcap to help cut down on the ridiculous foaming I get during aeration and reduce blow-off as well.
On the other hand, it is definitely possible to boil over your wort from just excessive heat; the hot break foaming only makes the situation worse. Also, if your wort is really thick and syrupy (well above 1.100, say you’re doing a partial boil but added all your LME/DME to 2.5 gallons) you can have boilover problems that fermcap won’t help either. Fermcap just helps prevent boilovers and blowoffs by significantly reducing the foam-forming potential in the wort. Happily, it also drops out by the end of fermentation (I hear it adsorbs to the yeast when they drop) or else there’d be a problem with head retention.