The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

granite cut out from counter top - use it as a baking stone?

uncle goosehead's picture
uncle goosehead

granite cut out from counter top - use it as a baking stone?

The topic says it all.  I have a granite piece that would make a lovely baking stone.  But:

-do they treat the surface other than polish it?  

-will it explode or anything in the oven?

If anyone has any experience with it, this would be grand to know about.  This piece has been hanging around for about 5 years, and I just found it again.  It is almost useless for anything else.  Measures 22"× 20", and 2" thick.  

clazar123's picture
clazar123

If the oven rack can hold it you can use it in the oven. Granite is formed by heat and pressure so a little oven heat won't hurt it unless it is a particularly crystalline type with a lot of crackly looking veins/fractures. It is usually the white or light gray type that almost looks like marble that may crack.

Sometimes it has a surface sealant. I believe just a few good heatings with some open windows would take care of that or a nice surface heating outside with a handheld torch. I have seen youtube videos of a granite slab being heated by a blow torch from below to cook steak and eggs on top. Amazing!

uncle goosehead's picture
uncle goosehead

Thanks.  It is black with some flecks in it.  That's all.  I will give it a try.

Toad.de.b's picture
Toad.de.b

My $.02:  Most kitchen/bath countertop granite on the market is "5/4" (i.e., 1.25" thick).  A ~1 sq ft slab of that represents a substantial heat sink, esp. if it starts out cold (e.g., in winter).  Bad news is, that'll take quite a spell to heat up in your oven (will absorb oven heat until it can no more).  So pre-heat your oven earlier than you're accustomed to.  Good news is, as a heat storage sink, it will hold heat very nicely when you open the oven door, reducing demand on oven to replace heat once door is closed.

Much (most?) current granite is polished and coated on one side at the quarry.  That coating is presumably food safe, since the slabs are often destined for kitchen worktops.  However, once that coating is heated, you'll have a likely toxic cloud that you shouldn't let mix with your edibles (the dry, polymerized coating is inert to cooking solvents: water, oil, vinegar).  So, as previously posted, burn that off, either in an otherwise empty and very hot oven, or outside on the barbeque, burn pile or blow torch.  And to be safest, consider flipping it over in the oven so that the formerly coated surface is never in contact with your bread.

Let us know how it works for you.  Great idea -- countertop purveyors have (literally) tons of sink cutouts lying around to practically give away.  I think I just read that Phil's Tarlee Miche (latest feature on TFL homepage) was baked on granite.  Hard to beat that as a testamonial.

Happy Baking,

Tom

Doc.Dough's picture
Doc.Dough

Granite doesn't hold a lot of heat, and the thermal conductivity is quite variable (1.7 - 4 W/m°K) so it might be great, or not.

If it is a 2" thick slab rather than two 5/4" pieces bonded together, then you can probably just turn it over and use the back side for baking, but I agree that there is likely to be a sealant on the "good" side that should be removed.  If it is a bonded slab, then you have another issue with whatever it was that they used to make the bond.  You might just call the stone guys and ask about both the sealer and what they use for bonding.

uncle goosehead's picture
uncle goosehead

The slab is indeed 2" and is one piece, not laminated.  I suppose part of my wish to use it is that it is a very pretty piece of stone.  But the back side is rough rough rough, not something that looks bake-able.  I bake in a convection oven in the kitchen and sometimes on a natural gas barbeque, and also on a portable metal fire pit.  So I may start out with a barbeque flame out on this and go forward from there.  I used to do flatbreads on rocks facing a fire and now think a tip-up beside a fire might work too to eliminate any sealant but residual chemicals do give me second thoughts re using it at all.  

At the moment I've been using it as a cool place to put a dough to rise slowly, with a large bowl over it in a coldroom.  It may be a heating up thing to consider with the mass of rock with this.  I've had an history of baking some breads from a cold oven.  This will not be the thing to use for that method. 

PastryPaul's picture
PastryPaul

No issues

Mind you, I did stick it on my outdoor fireplace face down on the grill, hoping to burn off any coating. Seems to have worked. I also like the idea of torching the sucker.

Cheers

adm's picture
adm

You should have no issues with it. I have one and it works great.

As others have said, make sure to give it plenty of time to heat up first - I find at least an hour is needed in my (electric fan) oven.

Do give it a couple of heat/cool sessions in your oven at the hottest temperature prior to baking on it though in case there are any nasty sealants that need to burn off.

I have a granite slab that I got for free from a kitchen worktop company. They even cut it to perfectly fit my oven for free. As one poster mentioned, these guys have loads of offcuts that they normally throw away, so it's worth a phone call or two to see if you can snag a free baking stone....

PeterS's picture
PeterS

for water.  Granite can crack if heated very hot and then sprayed with water when steaming. It is like a lot of minerals and ceramics, it doesn't take uneven thermal shock well. I've got a nice granite scrap (free from the countertop company) sitting in my garage that I have to test one of these days.

As far as the chemical surface treatments, my understanding is that they are silicone and or silane (as in organosilicon) based. Probably very similar to a lot of silicon and or silicone based non-stick coatings and rubbers (as in spatulas) that are commonly found in the kitchen. A nice 2-3 hour roast in a 500F oven will cause most if not all of the volatile solvent component of the coating to evaporate. Whatever is left is going to be inert. These treatments are sold for kitchen use on surfaces that will likely have direct food contact, I'm going to assume that they are not hazardous enough to be a problem; toxic is probably too strong a term.