What is my stove making?

So after I let the stove cool off for cleaning, these things are in there mixed in with the ashes. They feel and sound like metal. Also, looks like pumice or lava rock.

What are these things?

 

Clinkers

 

Some say that elm will do that.
The Wood Wolverine

 

Yeah, I have been burning elm lately. That's about all I have left for the heating season.

 

there's 4 threads on clinkers
"Clinkers"? In my stove.

 

Yep, elm local to me (southern PA) produces big ol” clinkers. It’s the only species I’ve burned that did it.

 

Elm makes clinkers commonly...but depending on where the tree grew, and the minerals in the soil there, this can happen with other species too...I've had it a lot with Boxelder, some with Ash, and even oak occasionally.

 

One's I had last time would qualify as clumpers. I had my Baker wood/coal stove with shaker grates. These clumps were so big I had to use a poker to break them up to the point I could get them through to the ask pan. I was cursing, as you can imagine.

 

Ok, after reading a bit of that thread, I guess it's normal. If it's normal, there's nothing to worry about.

 

No worries. Best off to take care removing them as occasionally they adhere to the firebrick. If you try to ram around on the clinkers that are stuck to the firebrick they can take a layer of firebrick with them when they break loose.
This material has been described as residual mineral deposits that were in the wood.

 

I am assuming you guys are referring to wood with the bark, naked elm will not do that from my experience, oak, ash, mulberry will not do that even with bark. Green ash with the thick bark leaves black chunks in the stove, haven't had clinkers for over 30 years as all the elm here is barkless.

 

I pretty much only burn barkless elm, as I only fell elms that have lost their bark.

I get some mega clinkers every time I burn elm. I also get clinkers from box elder, and sometimes from other species.

 

I beg to differ...I get clinkers regularly, and no elm in sight...ash, oak, and boxelder were the main things on the menu this winter.

 

Ok, now for the 50,000 dollar question, what is diffetent, i use to work with a guy who had them really bad, so trees grown in this area are not the problem IMHO.
I will add this is 4 different stoves, no clinkers what so ever.

 

Did some reading, rabbit hole with no bottom!

 

Best thing i could find was noncombustibal salts and minerals entrenched in the wood fibers liquefy and melt togethet, ash melt. Good enough for me.

 

I burn lots of elm, very very little of it ever has bark. I get clinkers. They don’t bother me. Just the nature of the beast I figure.
Living in the sand hills I often wondered if it wasn’t sand embedded in the wood and trying to turn into glass in my stove, but I really think it’s just minerals in the wood.
No matter, just scoop em out with the ashes, not a problem in my situation.