I fermented my first batch of extract in a plastic 'ale pail' using an airlock with the following mixture in it:

• 50% tap water; and
• 50% whiskey

It never bubbled. Not even once. But when I cracked open the lid and took the SG, it was obvious that fermentation was occurring). I was told by someone recently that airlocks consisting of either distilled water or alcohol usually don't bubble:

"Usually won't get bubbles if just using distilled water or alcohol, not enough surface tension."

I'm curious as to what this means (exactly), because to me (an uninitiated rookie), if CO2 is trying to escape, it shouldn't matter whether you're using alcohol, distilled water, tap water or crude oil: gas has to escape!

So what's so special about both distilled water and alcohol that causes it not to bubble when used inside an airlock?!? I guess I'm hung up on the meaning of "not enough surface tension".