metal cores

Hey folks, I wanna beat this dead mule a little bit more. Question, would ceramic paint work in a metal riser? Some of these coatings are rated for 3200F and higher. I understand that the interior would be very smooth but I believe that could be worked out by adding some very small restrictors to encourage the mixing needed to burn all or most of the stuff we want to get burned. Has this been tried before? Please share your thoughts and ideas. Thanks

Hi Doug;  Welcome to permies.  I have not heard of this being tried... Ceramic paints/products are pretty tough and it is possible you could accomplish this. I would worry that one flaw in the paint would allow the metal to be exposed to damaging high heat.   However, this seems like a very expensive way to go. Fireclay and perlite makes for a great riser, cost is very,very low, ceramic fiber tubes are now available that work very well , although again cost is up there. Ceramic boards are being successfully used making a square riser. Insulating firebrick is another great choice ! Split firebrick is also a favorite choice for risers.   Rather than ceramic paint I suspect that the ceramic tubes would make the best riser.   Good luck , give it a try and let us know how well it works for you.

These paints, or coatings can withstand advertised temperatures. However, they have to be applied to alloys that won't. The metal will degrade, and the coating won't have anything to adhere to. It will then crack and flake off.

Thanks Jonathan, that's the kind of info I'm looking for. Do you know of any affordable/available alloy that would work or how long it would take to degrade if applied to regular carbon steel at rockety temps? I got 3 heating seasons out of uncoated .250 wall steel before the flaking happened.

My opinion is that it's wasted effort to try to make metal last in the burn tunnel or heat riser, outside of an exceptional application like a mobile unit that is subject to frequent vibration. Many people's experience indicates that refractory and insulating materials will do the job better and usually cheaper. I know some people are skilled at metalwork and more comfortable with that than with masonry work.

Yes Glen , I guess I was grasping at straws because I am a metal worker. Next question, when you folks talk about split firebrick are you referring to the brick that would come in a wood stove? The 1 1/4" heavier brick? I have s bunch of those and that will become plan A now if they're suitable. It'll be wrapped in ceramic blanket that I already have. Again thanks for all of the good feedback!