Igloo Cooler Mash Tun

I decided that it was time to try out all-grain. After shopping around, I found a 50 quart Igloo Ice Cube cooler that I liked. It's large enough to hold plenty of grains for high gravity 5 gallon batches but doesn't have a huge footprint, so it should work for lower gravity batches as well (if I ever felt like making a low gravity batch). I found it for $19.99 at Target.

The big problem was that the cooler didn't have a drain in it. From what I can tell, this only occurs in the 50 quart, not the 48 quart, which is visually identical but has a drain (and I imagine that it might be more insulated, as the cost tends to be significantly higher, if you can find them). Not having a drain was a problem that couldn't be easily fixed by a drill.

I pretty much followed the directions I found at the BrewTech blog, the major difference being that I wasn't using a pre-existing hole in the cooler wall. The hole I drilled was perfectly sized for the brass nipple to thread through. It doesn't even leak there at all.

One place that it did leak was where I threaded the nipple into the valve body. That's probably because I (like an idiot) didn't remember to use teflon tape on the connection. It got tightened naturally and I couldn't back it out to tape it afterward. So, I grabbed a tube of silicone sealant (for use on faucets and such) and sealed up that joint. No leaks after that. I just bought some tape to use on the barb fitting, since that one will loosen and leaks a very tiny bit when the drain is open. I also added a rubber washer to the inside to help seal against the cooler wall, but it probably would have been fine without that.

I wrapped the thing with blankets and threw some hot water in to test. It dropped 8 degrees over the first hour, which worried me a bit. Then I realized that hot water doesn't benefit from three things:

1. Insulating value of the grains - The grains themselves have an inherent insulating value
2. Sugar solution - A sugar solution loses heat slower than plain water
3. An exothermic reaction - The conversion process creates some amount of heat itself

Since the hot water test, I have done a mash with 12 pounds of grains during which it dropped 0 degrees! It started at 152.4 and ended at 152.4. I was amazed. I had done some research and knew that the hot water test wasn't indicative of mash performance, but I still expected to see at least a one degree drop.

The only other modification that I did to it was to drill some holes in the lid, which was hollow, and spay some expanding insulating foam that I got at Home Depot in there. It seems to work pretty well. If you try this, be careful, as the foam expands a LOT as it cures. I had to deal with foam expanding out of the holes for almost 12 hours. After the first hour I put a trash bag over the whole top and let it just leak (but only into the trash bag, so no mess). The excess leakage, once hardened, was easy to break/scrape off.

Pictures of the new mash tun:


It features a Michigan Brewer's Guild sticker on one side (I'm from Detroit, but now live in Chicago), an anti.team sticker by the faucet (that's my crew from college), and a Norther Brewer sticker on the other side (not pictured). I think this is going to become my beer sticker receptacle. I can't wait.