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Homeade baking stone. glaze questions

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seanseansean's picture
seanseansean

Homeade baking stone. glaze questions

I had the idea to make a baking stone out of the clay at the University I am attending.  I am unsure as to what the claybody is comprised of, but that is not the question I am here to ask.  If the glaze that is available is food safe then would glazing the baking stone have any ill effects?


 


I am under the impression that unglazed quarry tiles are bought because the content of the glaze is unknown, are there any other precautions aobut glaze?  The stone would cease to be porous would that affect it haphazardly?


Eager to bake some bread,


Thanks yall,


Sean

mrfrost's picture
mrfrost

Never seen a glazed baking stone, or tile. Apparently there are some out there though.


Assuming that the clay is safe(?), and as long as the glaze is food safe, why not do one of each, for comparison sake. Otherwise, if you can only make one type, probably go with the unglazed. Less likely to get unexpected results.


Or you can glaze one side and leave the other side unglazed. Probably end up with the best of both.

Chuck's picture
Chuck

I am under the impression that unglazed quarry tiles are bought because the content of the glaze is unknown


Nope. (It's true glazes disturbingly often contain lead, but that's only a secondary reason why baking stones are unglazed.)


Baking stones do at least a couple of different things:



  1. absorb, store, and release heat for more even temperatures

  2. produce a crispier/drier bottom crust (especially on pizza:-) by sponging  moisture out of the crust as it bakes


Although glazing might have only a small effect on the first benefit (by reflecting heat), it would completely bollix up the second benefit. (I also suspect [but don't really know for sure] that glaze would be more likely to crack in the constant heatings and coolings of an oven.)

Mini Oven's picture
Mini Oven

I wouldn't glaze the baking surface.  Look for a recipe for thermal clay, that which is used for cooking pots on open flame, which is more likely to include more fine flint and fine grog than normal pottery clay.  Don't be afraid to add some shallow relief designs into the surface, something that imprints the bottoms of your loaves saying that they're special.


Very important not to have any air pockets in the slab itself.  Let it dry slowly and the heating up time in the kiln should also be very slow.   Other than tightly working the clay, the baking slab could be made using an casting process; a vibrated slurry (to force air bubbles to rise and pop) poured onto a dry plaster slab and allowed to build up to the proper thickness with the moisture being absorbed by the plaster underneath. 


Mini

dwcoleman's picture
dwcoleman

Perhaps you can obtain some refractory mortar, and pour it into a cast.  I have seen a webpage that chronicles someones attempt.  They reinforced the casting with steel rod internally I believe.