My ultimate goal is to go all electric including a RIMS tube for mash temp maintenance but there's a long list of things I need to do including a 200a service upgrade so I thought I'd try something else temporarily.
AnoldUR and I (and a few others) threw around ideas for an insulation material that could withstand direct heat. I know some folks put reflectix on their metal tuns and light the fire, but mine starts melting in 3 minutes flat, usually after I forget to remove it during heating. Anyway, AnoldUR had pulled the trigger on some mineral wool semi-rigid insulation and it was so cheap that he bought two (and kindly donated one of them to me).
Mcmaster.com 9328K41
Mineral Wool Insulation Plain Faced, 1" Thick, 24" X 48" Sheet
In stock at $6.19 Each
The first observation is that the stuff is very delicate. It can't really be handled and for sure, you couldn't just wrap it around your MLT and hold it on with bungie cords. It would fall apart. I was going to wrap it with some really thin aluminum flashing but my dad bestowed some nice 16gauge aluminum sheet. I cleaned it up with some gator grit fine pads on my grinder and put some decorative hash marks on it to hide current and future scratches.
After I form this around something like a corny keg, I'm going to hold it all together with some spring latches. More to come.
Since there are a lot of posts before I actually made progress, here's a link to the post that gets to business.... https://www.homebrewtalk.com/f51/direct-fire-mlt-insulation-project-154652/#post1819825