A lot of people solve this problem by wrapping their carboys with a towel but I found that we were constantly running out of towels only to find them wrapped around the carboys. This was not an ideal solution, so I took matters into my own hands and made a trip to Fabricland. The result was these carboy cozies, which are inexpensive, easy to make and much more handsome than a towel.
You can pick any colour or pattern of fabric you like but if you want something fancy and bright I'd recommend lining with a thicker black fabric to absorb as much light as possible. I used black flannel and made 2 x 3 gallon cozies, 1 x 10 gallon cozies and 3 x 1 gallon cozies for $20 which is a bit cheaper than going out and buying 6 towels, which won't even manage to cover the 10 gallon ... bucket. (OK, so it's not really a carboy cozy at that point but it sounds better then bucket cozy!)
To make one is simple, all you require is a piece of cord or a fabric strip and an A x B rectangle of fabric where...
A = the measurement around the circumference of the carboy with 1.75 cm (1/2") added for the seam allowance.
B = the height of the carboy plus 2.5cm (1") for the hem at the bottom and about 5 cm (2") for an extra-large hem that you can stuff the cord in to pull it closed at the top.
To make the cozy,
- Cut a rectangular piece of fabric that has A x B dimensions
- Sew the small hem on one A edge and a larger hem that you can thread the cord through on the other A edge.
- Sew together the B edges, leaving the large hem at the top open to leave room for threading the cord
- Thread the cord through the top hem and cinch shut.
Now the only thing left to do is to make some beer and find the coolest space in the apartment and cozy it up!