Homebrew Underground

In an earler post I wrote about keeping the fermenter cool during fermentation. In that example the fermenter was wrapped with a couple of wet towels. I also mentioned you could use a T-shirt instead of towels. Below is a shot of the fermenter in a tray of water using a T-shirt:

Using a T-shirt is a little more convenient because you can just slip the T-shirt over the fermenter (slipping the open end of the T-shirt from the bottom of the fermeneter). It will stay in place by itself. When using towels, I found I had to pin them together with safety pins to keep them from falling off the fermenter.

The T-shirt may be able to cool the fermenter more efficiently because it should be a tighter fit than the towels and the wet fabric will be in better contact with the fermenter. In theory, when water evaporates from the T-shirt, there should be better heat exchange with the fermenter. I haven’t been able to confirm this, though.

Don’t forget to fill the tray with ice. It will keep the fermenter cooler than when using only plain water. As the ice melts, the fabric will wick up the water.

By the way … that last batch of beer that was kept cool with the towels came out pretty good. I noticed one more benefit, too. When I transferred the beer from the fermenter to the carboy it was almost fully clarified. I think that was due to the fact that the beer took 7 days to ferment. In earlier batches when I didn’t keep the fermenter cool, the beer only took 4-5 days on average to ferment.

You may find when transferring beer from the fermenter to the carboy that you have more beer than will fit into the carboy. Like many homebrewers, I have a 5 gallon carboy and my fermenter holds slightly more than 5 gallons. Recently, when making a batch of beer, the recipe called for just over 5 gallons. When I transferred the beer from the fermenter to the carboy, I needed somewhere to put that extra beer. No way was I going to throw it away!

I also make home made liqueurs and I will often use a 2 quart Mason Jar. I got the idea that just maybe I might be able to convert one of my Mason Jars into a carboy. All I needed was a hole in the metal lid just big enough for an air lock. I punched a hole in the lid and inserted the body of a plastic air lock, then I used clear silicone rubber sealant to seal the gaps on the outside between the metal lid and the stem of the plastic air lock. Shown below is a photo:

Silicone rubber sealant comes in a tube and is available at most hardware stores. Allow the sealant to dry overnight. Use common sense and be careful not to allow any silicone to come into contact with the inside of the carboy where it can come into contact with the beer. You can sanitize the lid and glass Mason Jar before using it in a batch of brew.

The “mini-carboy” works like a charm.

When making ale, it is a good idea to wrap the fermenter with some wet towels (or a T-shirt) to keep it cool during fermentation. Fermentation tends to raise the temperature because heat is generated by the fermenting yeast. The principle of using wet towels or a T-shirt is like an evaporative cooler. When the water in the towels evaporates, it cools the towels, and the heat is transferred from the fermenter into the air via the wet towels. This can lower the temperature as much as 10 degrees below room temperature. The effect can be enhanced by blowing an electric fan on the fermenter.

Fermenting at too high a temperature will cause noticable off-flavors in the beer. It is most critical to establish a cool temperature within the first 8 hours to set a slow, even pace of fermentation. Off-flavors can occur at this time if the fermentation is too hot and too fast. You don’t want to slow down the start of fermentation, either, so it is best to wait about 5 to 6 hours after pitching the yeast to allow a quick start of the fermentation, then slow it down by cooling the fermenter. Keep it cool for the duration of the fermentation (about 4 to 8 days).

Ideally, you want the temperature of the wort to be 70° Farenheit when pitching the yeast. Also, if you are rehydrating dried yeast, it is a good idea to prime the yeast at the same temperature as the wort. The yeast will experience little or no shock this way and will stand the best chance of a rapid start of fermentation. When you pitch the yeast into the wort, aerate it thoroughly with a stainless steel whisk to bring oxygen into the wort. Yeast needs oxygen to get fermentation started.

It is best to keep the fermenter in a cool place during primary fermentation. Although the recommended fermentation temperature can vary depending on the brand of yeast, generally, the ideal fermentation temperature will be 60° F. During fermentation, the beer heats up, so even though you may have a room temperature at a chilly 70 degrees, the fermenting beer will tend to be hotter than the surrounding air.

Below is a shot of the fermenter with wet towels wrapped around it. The fermenter is placed in a tray filled with water and the towels are allowed to soak up the water. Wicking action causes the water will rise to the top of the towels and keep them wet. You can also cause the water to be cooler by placing ice in the tray. The melting ice will make cooler water. See the equipment page for a photo of the tray. The one I bought is called a "terra tray" or "Planterra Tray". It can be purchased from a local nursery supply or Home Depot.

It ain’t pretty … but it does the job!