The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Granite Slab as Baking Stone

Occabeka's picture

Granite Slab as Baking Stone

Hi all. I am new to this forum and I would like to seek your advice.

I recently came into possession of a piece of black granite slab 3/4 inch thick which I intend to use as a baking stone. One surface has been polished to a sheen in the factory. I found out that the manufacturer uses a chemical to reduce the natural porosity of granite to prevent staining; either acrylic or polyurethane as a sealant.

My questions are: 1. Are these chemicals food-safe, since I will be baking on the slab?

2. How does one remove the sealant from the granite?

Any help or suggestions greatly appreciated. Thanks.



firstfloorfront's picture

Hello Occa (from Australia I guess :-))

I've been using a granite floor tile (30cm x 30cm x 1 cm) as a baking stone for some time with no noticeable problems. When I bought it from the tile store I was told that the stone had just been polished but not treated, that was down to me if I wanted it done. I've only got a small small oven and the tile is ideal. Even at 1 cm thick it holds the heat very well.


clazar123's picture

I know the shiny side is pretty but can you use the unpolished(but usually smooth) side for the baking?

Janknitz's picture

Polyurethane and/or acrylic are NOT meant to be heated at high baking temps and may melt and break down into toxic compounds.

This could be dangerous to breathe and I certainly would not eat food that was baked on surfaces treated with these substances!

Occabeka's picture


That was what I was worried about too. I have tried to google for the material safety data sheet of the above substances, but was not successful.

It looks like the polished surface will have to go before it goes into the oven. Will have to grind it off.

Thanks for your input too, Peter and clazar123.


Barbara Krauss's picture
Barbara Krauss

Or you could use the granite for your kneading surface and look around for another baking stone.

macZiggy's picture

....a granite fabricator in your neighborhood.  Ask the granite person to take the polished finish off.  That should bring the stone back to slightly less finished state, but still smooth.  I think the cost would be reasonable.

Or, you could buff the finish off with a sander (or a grinder) yourself (wear a mask).  I have done that with green marble tiles and the green marble was softer than I expected and quite easy to sand down.  I think black granite would be harder, but if it was a small area, you could definitely manage it.  There are videos on YouTube that give a good description of how to accomplish that with multiple grade sandpapers.  Or search the web.

Occabeka's picture

I have sent the slab to a tiler to have the smooth surface ground off. The process looks easy in youtube, but I do not have the equipment to do it myself.

I should have it back in a couple of days.