Just thought I'd let you know about my first attempt at a mash tun. I've done a couple of all grain brews using a friend's set up and have seriously got the bug. Being on a very strict budget I have gone for the cheapest set up I thought I could get away with. I used a 5 gallon FV from Wilkos and fitted it with a braided steel hose and ball valve tap (sealed with a washer and some PTFE tape). I have lagged it with firstly an emergency foil blanket doubled up so four layers in total. Secondly I have fitted an old self inflating sleeping mat which has kept me warm on many a night camping in minus temperatures in Wales. This has the advantage of being able to inflate it with my 37 degree breath. I have lagged the lid with several layers of bubblewrap inside an envelope made from the same emergency blanket. Hopefully all this insulation is going to be able to keep my mash at the required temperature for long enough. I haven't done a heat retention test yet but will let you kow the results as soon as I have.