The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Kiln shelves

pantal's picture
pantal

Kiln shelves

After much searching for a clay stone, without any luck, I have found a local bakery school that sell baking stones cut from kiln shelves. I have asked them what the material is (no reply yet, but from what I understand they are mostly Cordierite).Being unfamiliar with kilns, their shelving and Cordierite I am eager to find out how safe they are in contact with food. I suspect a used one would not be safe because of contamination from whatever was fired on it, but that shouldn't be an issue in this instance.

dscheidt's picture
dscheidt

Cordierite is what many commerical baking stones are made of, including the popular old stone oven brand stuff. It's pretty well the best material available, strong, good heat conductivity, high heat capacity, low expansion, resistant to thermal shock.  And it's fairly cheap (and cheaper than some of the inferior alternatives).  A kiln shelf is likely to be a cordierite-mullite mix, which will have better mechanical strength, but pretty similar thermal performance. 


Only health risks are burning yourself or dropping it on your toes.

Zeb's picture
Zeb

I have a kiln shelf as baking stone. It seems fine so far and more durable than the pizza stone that I started off with which cracked in two after about 4 months.  Bath Potters (England) cut the shelf to the size I wanted which was really useful.

pantal's picture
pantal

Thank you.


What size did you get, Zeb? What is the ideal thickness for bread baking?

Zeb's picture
Zeb

Just a note to this thread..... Pantal sent me a pm which I replied to back in November last year. See below for what I said.  I don't know if they saw the reply or not, as the conversation went no further. It looks as if Bath Potters are now supplying people with shelves for baking since then on a more regular basis. Mine was 3/4 inch thick.


I've uploaded a pic on this thread today http://www.thefreshloaf.com/node/21540/baking-stone-london-uk#comment-151813


 


' I think I phoned Bath Potters and had a chat with them. And I told them that I wanted a kiln shelf and we talked about thicknesses and whether they were food safe or not, (they weren't 100% sure). They cut down an existing one to the size I wanted and a friend of mine who was going out there to get some pots fired collected it for me.  They are fairly local to me.  Do you want me to measure the one I have?   I think it cost somewhere in the region of £25 but I can't remember exactly now.  ' 


 

pantal's picture
pantal

Thank you. I did not see your reply until this popped up in my e-mail. I don't think I will need your measurements, but thanks anyway.

Daisy_A's picture
Daisy_A

Hi pantal, 


Cordierite is currently held to be food safe by the FDA. In data sheets mullite is descrbied as generally non-toxic, unless ingested in large amounts. Not a cast iron guarantee but the current findings! Dust is a greater problem with silicates so avoid cracked or crumbly stones.


Potters apply 'slip' to their shelves to make them less prone to staining and sticking, which also seals the surface, meaning less dust in general.


Potters also advise rotating the stone after each use and storing it on its side when not in use to avoid stress fractures.


We've been having a UK based discussion on this too. On this thread I talk about how I coated my own kiln shelf with a very dilute flour, water, starter mix in place of slip. This is the link if it is of help to any other bakers using kiln shelves.


http://www.thefreshloaf.com/node/21540/baking-stone-london-uk


Debate arising on this thread suggests that not all these measures are necessary. However there is now some useful information on cleaning instructions on this thread. 


Best wishes, Daisy_A