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-   -   Can these be used for oven floor? (http://www.fornobravo.com/forum/f44/can-these-used-oven-floor-17274.html)

pdqtom 01-22-2012 06:19 AM

Can these be used for oven floor?
 
I am gathering materials to build a 42" oven and have come across used "tiles" from a commercial pottery kiln. These are actually High temp shelves used in the kiln and I can get them reasonably priced. They are approx. 1" thick and 20" square. Are these acceptable for "flooring" in the oven. I was going to use firebrick but came across these. They are much thinner than using firebrick, should I use one layer or perhaps two or stick with the firebrick?

This forum is awesome, by reading it I now know too much and need to stop researching and start building!

Les 01-22-2012 08:34 AM

Re: Can these be used for oven floor?
 
I would personally double up for the mass. More importantly, do you know what was being fired in the kiln? Many of the products may have contained lead. No clue how much could possibly get into the tile and then leech into the food. It's a question I would ask...

pdqtom 01-22-2012 07:46 PM

Re: Can these be used for oven floor?
 
Thanks for the reply. The tiles were used only for stone ware. They said that the glazes they use have no heavy metals. The owner also said she was about to order some replacement tiles from Mexico and could add additional to her order for me at her cost, $36 each. I have also thought of going ahead with firebrick with these tiles on top to minimize joints.

GianniFocaccia 01-22-2012 09:19 PM

Re: Can these be used for oven floor?
 
I went with 1.25" soapstone directly on top of 2.5"-thick firebrick thinking that this floor thickness is still thinner than my dome.

Harbison Walker (ANH Refractories) has 24"x12"x2.15" refractory tiles which are made of the same material as their firebricks. A year ago these were $32 each at their location in Los Angeles. They have a location in Dallas.

azatty 01-25-2012 02:01 PM

Re: Can these be used for oven floor?
 
I'd say used tiles are a no-no; new ones, I don't know.

Pottery glazes are typically made of silica, alumina, a flux, and a colorant. The fluxes can contain metallic oxides which can be toxic. She may say that no "heavy metals" were used, but that only eliminates part of the periodic table. And then there's the colorants. You have no idea what their chemical composition is. Unless she knows the exact comoposition of the glaze, I wouldn't be enthusiastic about cooking on them.

It also seemed to me that the kiln shelves were very porous when I looked at them. I'd be interested to see how they work out, though. It could lead to a much lighter oven.

brickie in oz 01-25-2012 03:56 PM

Re: Can these be used for oven floor?
 
Quote:

Originally Posted by pdqtom (Post 126084)

This forum is awesome, by reading it I now know too much and need to stop researching and start building!

Cool! :cool: Dont forgot we need lots of pics...:D

eatingmorefood 03-25-2012 08:23 PM

Re: Can these be used for oven floor?
 
We used 2 layers of 1 inch thick 14x16 in #2 pizza stones and the floor works great. See it here : Pizza Making Supplies, Pizza ovens, DIY pizza ovens, DIY wood oven, Cutter, Pizza Stone, pizza knife, spice shaker, crushed red pepper, grilling pizza, grilled pizza, pizza BBQ, BBQ pizzas, make pizza on grill, making grilled pizza, smoked pizza, woo

david s 03-26-2012 04:56 AM

Re: Can these be used for oven floor?
 
I will be interested to see how they stand up to repeated firings. My guess is that being thin, they will be more prone to cracking. However as you are selling them this won't be a problem for you and it may well generate more sales from those that you will need to replace for others.

david s 03-26-2012 05:05 AM

Re: Can these be used for oven floor?
 
Quote:

Originally Posted by azatty (Post 126276)
I'd say used tiles are a no-no; new ones, I don't know.

Pottery glazes are typically made of silica, alumina, a flux, and a colorant. The fluxes can contain metallic oxides which can be toxic. She may say that no "heavy metals" were used, but that only eliminates part of the periodic table. And then there's the colorants. You have no idea what their chemical composition is. Unless she knows the exact comoposition of the glaze, I wouldn't be enthusiastic about cooking on them.

It also seemed to me that the kiln shelves were very porous when I looked at them. I'd be interested to see how they work out, though. It could lead to a much lighter oven.

It is not only toxicity from the glaze that is the problem. There are a whole host of nasty chemicals produced from the clay body at biscuit firing temperatures including formaldehyde and sulphurous chemicals.How much would be in the shelves is anyones guess.


3.1 Hazards of firing
When clays and glazes are fired, they release various gases, vapours and fumes, which can adversely affect health if inhaled. The gases, vapours and fumes which may be emitted during firing include:
carbon monoxide
formaldehyde
sulphur oxides
halogens metal fumes
formed when carbon-containing compounds from the organic matter found in most clays and many glaze materials are burned in a limited oxygen atmosphere, such as electric kilns. Carbon monoxide is an asphyxiant
formaldehyde may be formed when organic materials decompose. It is an irritant of the eyes and upper respiratory tract, a sensitiser which may lead to asthmatic symptoms in some people and a suspected carcinogen. Its vapours may form explosive concentrations in air
sulphur-containing compounds are found in many clays and glaze ingredients. When these decompose with heat, they release sulphur oxides, which when combined with water form highly corrosive sulphuric acids. Evidence of these corrosive emissions can usually be seen in the metal parts above kilns
chlorine and fluorine may be released when clays or glazes containing fluorspar, iron chloride and cryotile are fired. Both gases are very irritating to the respiratory tract
various metallic compounds will undergo complex chemical reactions during firing. Fumes formed from lead, cadmium, antimony, selenium, copper, chromium and nickel are all toxic if inhaled; some are even carcinogenic. In addition, fumes may settle and contaminate dusts in the kiln room
Revised October 2003
4 of 6
Information Sheet IS13 Ceramics Hazards
nitrogen oxides these may be produced by the decomposition of nitrogen-containing compounds or by the action of heat and/or electricity on air in the kiln. Ozone may also be formed, and
both are strong lung irritants

shuboyje 03-26-2012 06:52 AM

Re: Can these be used for oven floor?
 
Kiln shelves are much more thermally conductive and could really throw the balance of the oven off, especially with the high dome of a standard Pompeii oven.


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