I've been building up my equipment to do all-grain. My mash tun is a keg with the weld-b-gone bulkhead and standard ball valve attached. It has a 12" domed false bottom. It has 2 layers of reflectix insulation around it as well as on top. I also put the lid of my old 5 gal boil kettle on top of the cut out as it fits and helps keep all the vapor in. I did a test to see how good it could hold temperature. I heated up ~8 gallons of water and after dumping it in the mash, putting the insulation on and getting the electric thermometer going I got a reading of 68.28 C or 154.9 F. After 1 hour the temperature was 65.94 C or 150.692 F. So it lost 4.212 F over the hour. I would imagine that this is good as I just had water in there and no grains to hold the heat. I hope to get good efficiency out of this mash and also achieve/maintain target temperatures. I will probably put some more insulation on the bottom of the keg just for the heck of it. How's my mash seem so far? I'm still working on my sparge arm. Otherwise I just need get a stand of some kind going.