Stoneware Clay ok for "sticking" together firebricks in burn tube and riser?

Just starting on a build, and was looking for information on part of it when I realized (to my potential chagrin) that the dry clay I have been mixing into slip to "stick" my firebricks together is stoneware clay, and not fireclay. Will this pose a problem? Is it ok to continue my build, or do I need to completely dismantle what I have done (which isn't really that much, though it represents a good deal of time), find some fireclay and start over?

It needs to be fire clay. Stoneware fires very hard and it shrinks.

N. Taylor : Here on the East Coast there is no collective history of Cob or Adobe` and the best finish plasterer I know trained his eye and hand working untold 1,000s
of hours working with bondo, Skill and knowledge is where you Find it !

I have two ideas for you, I did a google search here in Permies for Making Cob Test Bricks and immediately found pay dirt ! A second very good resource is ;
The Hand-Sculpted-House, Ianto Evans et all, you may be able to get it through your local lending library, my copy came second hand from Amazon I think
or go to the source Cobcottage.com

Consider everything you have done 'till now practice! In a well built, monolithic Rocket Mass Heater RMH, it is the Mass and the Cob that holds the combustion core
together!

We can test fire with dry stacked bricks just to prove to ourselves that fire can bun sideways ! Wetting the bricks,then coating them with clay slip will create a better
seal,It is possible to do this for your first outdoor test and then gently knock the bricks a part, all the cleaning they will require is rubbing two bricks together !

However, this merely shows you that the job of your Cob mortar is not to hold the bricks together, but far enough apart to deal with the bricks surface imperfections
and to build level and plumb, course by course, ! YourHeat Riser deserves a cob mortar made out of fire clay and builders sand!

If you are really interested, the better grade of stoneware have various materials added to retard expansion and contraction! This class of materials is called 'Grog'

One type of amendment is finely ground bone, many people who no nothing about china Know that 'Bone China' is good, without ever knowing or caring why !

If you are not learning, you are ready for that long 'dirt nap' ! Hope this was helpful and timely! For the Good of the Craft ! Big AL

Thank you, Dale and Allen, for replying.

Allen, I did know (from reading a post of yours in another thread somewhere) that the "mortar" was not there for the purpose of holding things together, but to deal with imperfections and achieve levelness/plumbness. I guess my use of "sticking" wasn't well though out. What I am gathering from your post is that stoneware clay is not ideal, but workable. Is that correct?

My main concern was that the stoneware clay would not fail under the high temperatures of the heat riser. The clay I have does have some sort of grit in it, that I am assuming is an additive to retard shrinkage. I thought it was just poor quality clay, because it didn't have fine consistency, but maybe it is actually good stuff.

The grit is most likely silica sand which forms a glassy finish and is much too hard. Fire clay is readily available. You need some. I have fired lots of stoneware. Not suitable at all.

N. Taylor : If You are going to buy it get fire clay ! The stuff I get with pick work has too much silt in it until i am 6 feet down !

It works for me ! My recommendation of the book is because each batch of local clay is different And you need to be able to
test each one. Generally if it is blue or grey most people disregard it out of hand ! Big AL !

Dale Hodgins wrote:Fire clay is readily available. You need some.

N., none of my local big box stores have any right now, but their websites list it at $8.22 for a 50-lb bag. You might be luckier with your local stores, and if so, it's definitely reasonable enough to buy some.
http://www.homedepot.com/p/H-C-Muddox-50-lb-Fire-Clay-100011882/100321936

Fireclay it is.

thanks everyone

Hi Folks...sorry I am late.

Please let me know what you finally do N. Taylor and how it turns out?

If other feel I have missed something...please let me know. However, if you are using "stoneware" clay...you should be just fine...I don't believe there is a need to dismantle your project, not actually stop using stoneware clay as a mortar...

"Fire Clay" is a refractory clay...and is actually added to Stoneware clay bodies to give it higher firing strengths...

I know that in building soapstone masonry heaters, some "old timers" only used a slurry mortar of soapstone dust and clay as the additive to "stick it all together."

Hope that helps...