I have some converted kegs I used as my mash tun and my hot liquor tank. I've been using the reflectix stuff to insulate them, as they do experience some temperature loss, especially during recirculation through the uninsulated counter flow chiller (heater?)
The reflectix I've been using works okay, but I get wort between the reflectix and the keg that gets funky after a while. And my HLT is close enough to the burner for my keggle that it eventually warps and shrinks and becomes ineffective, and I've got to rewrap, tends to be a pain. That and the duct tape doesn't hold up so well to the elements. So I'd like to do something a bit more permanent, and also try to do something with the CFC to insulate it as well.
One of the members did have his kegs sent off to a place to have a seriously large coat of bed liner put on them (I forget the member name, sorry..) and was wondering if anyone had tried anything else, such as spray or paint on bed liner that worked reasonably well, or a spray on silicone. Unfortunately, all the products I've found don't exactly list heat transfer or R ratings, since they're not really intended to be used as so-so insulators.
Otherwise, I'm going to be ordering a few different products and doing some experiments to see which ones work the best. Just hoping someone's already done the leg work here