The Fresh Loaf

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slate baking stones

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sybram's picture
sybram

slate baking stones

I've just acquired two pieces of slate to use in my ovens for baking bread and pizza.  I'll have them cut to size 14" X 22" today (my ovens are 24" wide).  That will give me an inch + all around.  My question...........Do any of you leave your stones in your oven all the time, or does the repeated expanding and contracting with the heating and cooling lead to their break down?  Also, do the stones impede or alter in a negative way anything else I would cook in the ovens? 


I have a whole slew of grands, and I'm really excited about being able to make two pizzas at a time in each oven.  On the other hand, I'm having visions of my poor old granny back hoisting those things in and out.  I do have a close to the oven storage place for them if needed.  They'll stand on end between a deep freeze and the wall.  I guess I should ask if that's OK, too, or should they be stored flat?


Syb

BayCook's picture
BayCook

Hi Syb-


    I've looked into this question before, and as long as your slate stones are not exposed to too much liquid, they should be fine for staying in the ovens.  I'm including steam in the liquids- it all has to do with moisture absorption by the grain in the slate. 


    If the stones take up moisture and are then heated, that moisture expands and makes cracks.  The solution would be to not make moist items at low heat, and not use steam in the baking process without venting the oven.  You can make wet stuff, but you have to give it a chance to dry while the stones are hot, in other words.


    I applaud your willingness to use alternatives to commercially available products- personally, I am using a 1/4" thick stainless steel plate- with a little care, you will have many years of use from your slates.


Of course, you know that any kind of glaze or applied finish on the stone is potentially toxic when heated...


 


 

Elagins's picture
Elagins

basically, slate is petrified mud and typically consists of distinct layers which often are already partially fractured and which may also contain air pockets. chemically, probably there's nothing amiss about using slate, but don't be surprised if the layers start coming apart and/or you start losing chunks out of the corners and edges.

another problem, which BayCook touched on, is that slate is highly susceptible to moisture, even in the form of steam, which invariably forms when a cold, wet dough is put on a hot stone.

finally, with regards to two pizzas at once, a lot will depend on the kind of oven you have, the maximum temp it can reach, the heat retention of your stones and the oven in general. i find that even with two 5/8" cordierite stones and an oven that can crank to an honest 550F, the temperature drop from even adding one pizza is generally enough to slow the baking time considerably if i load a second one. in fact, i find that the second pie invariably takes longer to bake than the first, even if i bake them one at a time and allow the oven to reheat between bakings.

that being said, good luck on this and i hope your experience proves everything i've said wrong!

Stan Ginsberg
www.nybakers.com

jdunivan's picture
jdunivan

I have used slate and what was said above happened to me. They started coming apart in layers. I am looking for a replacement. I was thinking of trying granite this time.


 


Jamin

Elagins's picture
Elagins

it's FDA approved for food, stable to 2500F and comes in many different sizes. take a look at my website.

Stan Ginsberg
www.nybakers.com

sybram's picture
sybram

Hi Jamin,


I checked out granite, too, and found it to be way to pricey for my pocket.  Did you have your slate ground off on top to make a smooth surface, or was it bumpy with the layering?

BjornErik's picture
BjornErik

I just got a granite stone for my oven 5 days ago.  There is a small business on the next street that sells headstones and counter tops.  I got a 1 1/4" thick piece cut to 21 1/2 x 14 1/2 for $50.  I've only done one baking so far, a ciabatta, and was very pleased with the results.  The only problem I have when baking on a stone with semolina or cornmeal, even parchment paper under the bread is it sets off the smoke detector.  They are hard wired together so when one goes off they all go off... I can't bake once people have gone to bed.

sybram's picture
sybram

That sounds wonderful, and it's just about the size I'll need, too.  I may check some similar businesses when my slates flake away.  s

sybram's picture
sybram

Thanks for your remarks, Stan.  Can the cordierite stones be custom cut?  Of course, I'll go ahead and use the slate for as long as it lasts since I've already bought it, but when it breaks down, I would be interested in the cordierite.  I really want my stones to be 14" X 22".  I went to your site, but didn't see that size.

sybram's picture
sybram

Thanks, BayCook. 


So you're saying to not do the water in the hot pan steam thing when I'm baking bread?  What about washing it?  I guess just a wipe off with a damp rag would do, huh?  This slate has no glaze on it.  And you think it's OK to just leave it in the oven all the time?

alannaturally's picture
alannaturally

Another alternative would be what I am currently using, which work great, fire brick.  I purchased them at my local Ace Hardware and lined my rack with them. The only downside is they are heavy (use the thinner ones).  I am currently using BBA and Amy's both which call for a burst steam in the beginning of the bake. Have never had any trouble with them even when I accidently spilled water on them when adding for the steam. 

sybram's picture
sybram

Do you put them in and take them out, depending on what you are cooking?  Are they just pushed together, or is ther some sort of morter you can use on them.  No, that would weigh a ton.  Doesn't food drop down between them, then, or are they really tight together?

BayCook's picture
BayCook

Sybram,


    slate is very moisture-sensitive- it fractures at a harsh look, and wiping it off with water would defintely lead to major cracking.  Steam is going to be a problem with the slate.  Baking a loaf with that nice chewy crust? Nah.


If I were you, I would use them for decorative flagstones outside, and go with Stan's cordierite, as shown here: (http://www.nybakers.com/equip.html)


 


or the firebricks also suggested, as a second choice.   Even  tile would be better than slate...  no mortar involved, by the way- mortar might be dangerous to your health.  Just push the pieces together.  It will work better than you expect


one thing I'm pretty sure would happen is that you will soon get little slate chips constantly coming up from the surface where you put the dough.  Kinda crunchy.


sybram's picture
sybram

Thanks for all the good ideas.  Since I've already had the slate cut, I'll try it and see (watching for crunchies).  If it doesn't work for me I'll be back to this thread in a flash.


Syb

jdunivan's picture
jdunivan

No. I just found couple pieces that were not to bumpy. I don't mind having a little texture.