A new innovation in RMH Batchbox construction.

Hi all;
My brain never stops going, I am always thinking/dreaming of different ways to accomplish things.
Thanks to Matt Walker's influence, I have become a big fan of "dry" stacking my Batchbox cores.
Matt has pointed out during his Stove Chat show, that all mortar will eventually crack and fail.
The constant heating and cooling that a Batchbox core is subjected to causes the firebricks to move and ultimately crack.
When using a clay/sand mortar reapplying is as easy as a wet finger of new clay mortar.
When using refractory mortar reapplying requires gloves or a trowel.
These quick fixes are relatively easy to apply, however, once the cracking starts it will always come back.
Over time (years) the core will need to be renewed.  
Clay mortar will pop right off, and refractory will need to be ground off.
And unless a brick cracks, a dry stack build is as good as the day you assembled it.

At DragonTech I use and sell an 1/8" thick Morgan Superwool gasket material good for 2200F.
I buy it in long two-foot wide rolls.
2.5" wide strips can be cut from this and be used for the horizontal and vertical brick joints.
If a person was building with used firebrick, the surfaces may not be smooth or level, an 1/8" "Mortar" joint is the fix.

If you used a Superwool gasket, it would last for the life of your batch, perhaps your grandchildren's grandchildren would need to replace it with new 2.5" strips...

I contacted Matt at Walker Stoves and told him of my idea.
His response was an enthusiastic reply of  "What A Great Idea"!  He said that some precast masonry builds have started placing a ceramic gasket between halves.
A great idea to use them in place of mortar with bricks!

I plan on building one of Peter's new compact cores after he is satisfied with its performance.
Perhaps I will assemble it with a Superwool gasket.


 

I'm confused,  is any form of mortar or chinking(the superwool)needed, or can one just dry stack?

If your bricks are in very good (new) condition, then you can dry stack them, if they are sufficiently supported.

Edit) I have two batchboxes and both are dry-stacked with no mortar.

I'm intrigued by the possibility, but we live in a seismic zone and get lots of shakes. Brickwork is one of the first things to go. I guess on one hand a dry stacked core and riser would be a lot quicker to rebuild with no cleanup required. I'm considering stainless steel bands to do the actual work of holding things together when the ground starts jumping.

Hey Phil;
Well, earthquakes of any severity do not happen in western Montana (until Yellowstone blows), so I have no experience with them.
I think a mortared core would crack at the joints and still shake apart.
With a dry stack core, you contain the exterior of the firebricks with an angle iron frame.
I think a dry stack could handle shaking much better than a mortared core would.

I've read your first post on this topic Thomas, and had to let it sink in. Horizontal seams with superwool, OK, gravity will take care of that very reliably. But I have my doubts about the vertical seams though. Not that mortar is doing a better job there, brick wandering is really a pain in the proverbial behind. In a couple of applications I am using simple steel wire to keep bricks and so on together. The wire will expand quicker than the bricks, but while cooling off it contracts and will keep the bricks in place.

Now you've mentioned a steel tension frame, that's what I'd call the closing stone. My latest development model was more or less built this way,  most of it is contained in a steel box.

I've never seen 1/8" superwool, the thinnest have been 1/4", years ago and no longer on the market now. But everything is different everywhere, so if it's available why not? There's a material called ceramic paper, is this similar to this superwool?

Hi Peter;
I have heard of ceramic paper, but I have not seen any in person.
I wonder if it is similar to Parchment paper.
My wife uses that for baking/cooking and although it gets brittle it never browns or catches on fire.
Of course, she is not cooking at 1800F!

The Morgan gasket is very useful, I can get it in 1/8" or 1/4" thickness.
I buy it in a 2' x 10' roll, I can also buy it as a 1" x 200" roll.
All of the Morgan Superwool products I have used have exceeded all my expectations!
Costly, yes but extremely useful!

EDIT)
A fellow rocket scientist just informed me he has been using this same Superwool gasket material.
He has been using it with waterglass as an adhesive for vertical or overhead use.
This would work perfectly for assembly purposes, although it might not hold after high heating.
I will experiment and report my conclusions at that time.

Tom, thanks for the discussion about using Superwool gasket as a way to seal the gaps between the refractory brick for a core build. It's too late for my current build and would have been a good solution since some of my new bricks had as much as several millimeter gaps due to casting inconsistencies of the brick. I used Sairset, but as you note, this will likely crack out over time.

Also glad that you made the comment about the person using water glass adhesive to bond the gasket to vertical pieces. I had to do a search since I wan't familiar with water glass and I found that Lynn Manufacturing, the same folks that make the Superwool have a high temp water glass product. I'll give this a try for attaching the gasket material to the back of my door frame to seal it to the face of the core. Future batchbox builds will include a dry stack core with Superwool gasket and steel compression frame.

Waterglass is also known as Sodium Silicate.
I buy mine from Lynn Manufacturing as well.