Ask Mr. Wizard

Cold Crashing with an Airlock


Adam Sickmiller - Cincinnati, Ohio asks,

After fermenting my beers I have always “cold crashed” the carboy or bucket in my temperature-controlled chest freezer or outdoors (during the cooler months) for a few days before bottling. This gives me a nice, compact yeast cake and seems to clear the beer very well, especially if I add gelatin. However, when I do this, my airlock works in reverse and seems to suck in plenty of air. I have become concerned about this method introducing oxygen into my finished beer. Do you think this is something I should be worried about?


This is a fairly common question and is clearly a concern to many homebrewers. Although I have answered a similar question before (in the October 2012 BYO), I will give a slightly
Response by Ashton Lewis.