Fireclay substitute

[arosheger]

I live in Montana, and I cannot find any supplier for fireclay. In fact they all say that fireclay is not produced anymore. Is there a substitute for the fireclay.
I am currently planning to build a Pompeii Oven. I need the fireclay for under the cooking floor.

[Les]

The fire clay under the floor is used to level it. You could probably get away with using sand. I would use the brick dust you are going to have from cutting the brick. Cut 50 of them in half and you will have more than enough to do the job (the 50 is a SWAG).

[david s]

I use fireclay as it that which is recommended, however at the relatively low temps we fire to I can't see why any powdered clay would not be suitable. If you have access to say powdered earthenware clay (ceramic/pottery suppliers) I'm sure it would suffice. Failing that you should be able to dig some clay from your own yard, usually below the topsoil layer, dry it, break it up and seive it. But that is a fair amount of processing which takes both time and effort.
Dave

[arosheger]

Thank you for your replies. As long as sand and brick dust are good enough to hold 1,000F (possible temp expected to be reached by a fire in a Pompeii Oven), I will use that idea. It's cheap and easy to implement.
This is the first time I am building an oven, am I going to encounter other places in the building project, where I will need to use fireclay such that the brick dust would not be enough? Reading through the plans, it does not look so. But for those who built their own oven, may have some insights of fireclay needs that the plans don't mention.

[Les]

If you make your own mortar, the clay is required there as well. I just read on another thread where Home Depot carries fireclay. If your store doesn't carry it, maybe they can have it shipped there. And the people that tell you it isn't produced anymore are full of crap. There are bags and bags of it down the street from me.

[Cheesesteak]

This, I believe, is the HC Muddox "fireclay" that HD carries:

[david s]

That bag says mortar clay NOT fireclay. In Australia bricklayers clay is wrongly labelled fireclay. it is not a refractory clay, but a product designed to make the mortar more "sticky". It still may be suitable buut is probably not a true fireclay, check with the manufacturer.

[dmun]

If your fireclay is just to mix with sand for your leveling medium, the cutting tray slurry will work fine. If you are going with the homebrew mortar, you're going to want fireclay. Your vendor saying they don't make it anymore is foolish. He just doesn't want to stock it (it's cheap). Try pottery suppliers.

[Cheesesteak]

Originally Posted by david s

That bag says mortar clay NOT fireclay. In Australia bricklayers clay is wrongly labelled fireclay. it is not a refractory clay, but a product designed to make the mortar more "sticky". It still may be suitable buut is probably not a true fireclay, check with the manufacturer.

I hear you - here's HD's page - which calls it "Fireclay."

Home Depot Fireclay

and . . .

Here's Muddox's MSDS sheet for this "Mortar Clay." The MSDS indicates it goes by two different names (Lincoln Fireclay or Mortar Clay). This stuff is apparently made by Gladding McBean - which is just 45 minutes or so up the road from me. I pass their quarries all the time. Makes me think it's the same stuff that's all around me . . .

Muddox Fireclay MSDS Sheet

[Cheesesteak]

Upon further review . . . the HC Muddox "Mortar Clay" is, in fact, Fireclay.

See here: HC Muddox Mortar Clay