Thanks for the reply. Is the cause of this due to an inadequate air lock or what. I always thought the airlock was there to prevent this. This morning before I left for work, the s type airlock was 1/4 on one side and 3/4 on the other. What do you think will it make it till I get home this evening?It usually happens when you are asleep. The foam knows you're gone and stealthily rises until your lid blows off and you have a serious mess to clean up. In all seriousness, just put a blowoff tube on it for safety. IME, it only happens when the beer is being fermented around...exactly around the temperature you are fermenting it at now.
ThanksThe airlock is fine. It has more to do with CO2 bubbles forming and as they travel upwards they are 'aerating' your beer. When you think about it, all foam really is is less dense beer (due to gas). When the bubbles are forming faster than the foam can diminish, it causes the foam level to rise. Hopefully it will make it. It really depends on how vigorous the fermentation is...the S-type airlocks are great for showing the pressure in your fermenter vs. the atmospheric pressure. Don't worry about it..if it starts pushing through the airlock, all you need to do is clean the airlock and place it back. The foam and the pressure coming out of the fermenter protect it pretty well from microbes invading.