Silicon Carbide Baking Surface

[BurntEdges]

November,

Very nice work here with the SiC baking surface.  As a matter of fact it has prompted me to order a nitride bonded SiC shelf which is due to arrive today.

I want ask you about how you load your unbaked pizza onto the SiC.  With only 6cm of clearance between your SiC and broiler element, how do you do it?  Do you just shoot it into that narrow opening with a peel?  Or, do you roll out the shelf from under the broiler element?  If so, does that compromise the bake in light of the SiC's high rate of thermal conductivity?

I realize that this thread appears to contain your most current information/experiences with the SiC material, but in an earlier thread dated October 2007 http://www.pizzamaking.com/forum/index.php/topic,5645.20.html , you replied:

"I will add that I would suggest trying to find silicon carbide that isn't nitride bonded.  It's a very strong material, but the nitride bonding decreases the density." 

The shelf that I purchased is nitride bonded, as is the one that you discuss in this current thread.  Maybe I misunderstood the context of the Oct. '07 thread, but it appears that you have changed your opinion on the benefits of a nitride bonded shelf.  What insight caused you to favor the nitride bonded version?

Also, I ran into a bit of a discrepancy with Seattle Pottery concerning the SiC shelf.  I'm certainly not asking you to speak on behalf of them, but want to relay what happened.  Their item #31257 (for which you provide an accurate link) is indeed a 16 X 16 X 5/8" SiC shelf.  But according to them, this unit is not nitride bonded, it is their "regular" SiC shelf.  She added that they do carry a 16 X 16 nitride bonded SiC shelf, but that it is only .394" thick.  She was not aware of them carrying a nitride bonded shelf, in that size, that was thicker.  I just want to be sure that I'm cooking on the same material that you have been using.  Since this material conducts heat so well, I opted to get the thinner (.394) nitride version over the thicker (.625) non-nitride SiC shelf.  Do you feel that will impact my baking performance or cause the baking surface to be more fragile?  Any problems with this shelf cracking when you place the raw pizza on it?  Did you do anything to prep the SiC shelf for its first use (cleaning or moderate temps)?  Sorry for peppering you with so many questions.    Thanks.

[November]

I want ask you about how you load your unbaked pizza onto the SiC.  With only 6cm of clearance between your SiC and broiler element, how do you do it?  Do you just shoot it into that narrow opening with a peel?  Or, do you roll out the shelf from under the broiler element?

I've done both, and both ways have turned out fine.

I realize that this thread appears to contain your most current information/experiences with the SiC material, but in an earlier thread dated October 2007 http://www.pizzamaking.com/forum/index.php/topic,5645.20.html , you replied:

"I will add that I would suggest trying to find silicon carbide that isn't nitride bonded.  It's a very strong material, but the nitride bonding decreases the density." 

The shelf that I purchased is nitride bonded, as is the one that you discuss in this current thread.  Maybe I misunderstood the context of the Oct. '07 thread, but it appears that you have changed your opinion on the benefits of a nitride bonded shelf.  What insight caused you to favor the nitride bonded version?

Nothing has changed, and it wasn't an opinion.  The nitride bonding decreases the density.  I purchased what I was told was a nitride bonded SiC shelf because the price was right and the thickness was suitable.  If it had been a 0.5" shelf, I wouldn't have purchased it because a nitride bonded shelf with those dimensions would have weighed too little.  I wanted at least as much mass as I had with my previous shelf.

Also, I ran into a bit of a discrepancy with Seattle Pottery concerning the SiC shelf.  I'm certainly not asking you to speak on behalf of them, but want to relay what happened.  Their item #31257 (for which you provide an accurate link) is indeed a 16 X 16 X 5/8" SiC shelf.  But according to them, this unit is not nitride bonded, it is their "regular" SiC shelf.

The product I was told I would get, and the product I received, has the properties of a nitride bonded SiC shelf.  What they're offering could in no way be sintered, or else they have a horrible supplier of sintered SiC shelves.  The density of sintered SiC is above 3.1 g/cm³, while the density of what they're selling is bellow 2.7 g/cm³.  I would also find it rare to get anything but nitride bonded SiC shelves at a pottery (kiln) supply store.  "Regular" in their case probably means it's not specified as a nitride bonded shelf as some name brand manufactures do, so they probably don't even know what kind of SiC it is.  If it isn't nitride bonded, it's curious that it pretends to be.

She added that they do carry a 16 X 16 nitride bonded SiC shelf, but that it is only .394" thick.  She was not aware of them carrying a nitride bonded shelf, in that size, that was thicker.  I just want to be sure that I'm cooking on the same material that you have been using.  Since this material conducts heat so well, I opted to get the thinner (.394) nitride version over the thicker (.625) non-nitride SiC shelf.

If they're claiming that the "regular" shelf is not nitride bonded, getting a thinner nitride bonded shelf is even worse.

Do you feel that will impact my baking performance or cause the baking surface to be more fragile? 

You don't have to worry about fragility, just the fact you are dealing with a lot less mass.  The baking performance will be vastly different.

Any problems with this shelf cracking when you place the raw pizza on it?

No.

Did you do anything to prep the SiC shelf for its first use (cleaning or moderate temps)?

I brushed all the surfaces down with a wire brush, then cleaned away the particle debris with damp paper towels.

- red.november

[BurntEdges]

November,

I appreciate the prompt reply.  I should have had this dialog with you before I bought the shelf!

In what way can I expect the baking results to be different with the thinner shelf?

In your dough recipes, what hydration % have you found to be best on this cooking surface?  Thanks again.

[November]

In what way can I expect the baking results to be different with the thinner shelf?

You won't be able to bake as large or as many consecutive pizzas.  I don't know the exact properties of the shelf you ordered.  At 63% the thickness, and possibly less dense still, it's conceivable that it won't even be suitable for baking any pizza.  Did they mentioned how much it weighed?

In your dough recipes, what hydration % have you found to be best on this cooking surface?  Thanks again.

I have already mentioned this before, but I don't bake pizzas directly on the surface that much because I like to use pans out of convenience.  I got the shelf to show proof of concept.  I don't know of a "best" hydration for the SiC surface as it would depend on what kind of crumb one is trying to achieve.  I usually start at 61.8% and go up from there depending on how long I let it ferment or what kind of flour(s) I'm using.  Lately I have been using the shelf in combination with American style pan pizzas (kind of like Pizza Hut's).  I keep the shelf at the second position, or about 11.5 cm from the top element, and place the 14" x 1.5" pan on top of the shelf.  I bake at 500°F for 6-7 minutes.

I do bake a form of quesadilla directly on the shelf using the broil setting all the time.

- red.november

[BurntEdges]

I did not discuss the weight of the shelf.  The checkout calculator shows the item weight as 8.8 lbs.  I thought that might be the gross weight for shipping purposes, but when I ran tracking info on it, FedEx listed the package weight at 10.5 pounds.  They're usually pretty accurate.  So without having an opportunity to weigh it myself, I would say that it's around 8 pounds.

Why may this shelf possibly be unsuitable for pizza?  Won't the thinner shelf re-heat quickly for consecutive bakes?

Can I improve its performance by placing it on top of a cordierite shelf?  Or is that defeating the whole purpose of the SiC material?  I guess the worst case is I return it & eat the shipping charges. -

BurntEdges

[November]

I did not discuss the weight of the shelf.  The checkout calculator shows the item weight as 8.8 lbs.  I thought that might be the gross weight for shipping purposes, but when I ran tracking info on it, FedEx listed the package weight at 10.5 pounds.  They're usually pretty accurate.  So without having an opportunity to weigh it myself, I would say that it's around 8 pounds.

At 8.8 pounds, that's just less than the density of what I have.

Why may this shelf possibly be unsuitable for pizza?  Won't the thinner shelf re-heat quickly for consecutive bakes?

If it can't store enough thermal energy to bake a single pizza, then it would be unsuitable for pizza.  You won't know that for sure until you try it, or if I had more exact thermal property numbers I could calculate it.  The ideal situation is to avoid reheating the surface at all.  A good stone/surface should be able to handle a couple pizzas back-to-back.

Can I improve its performance by placing it on top of a cordierite shelf?  Or is that defeating the whole purpose of the SiC material?

You can improve the heat capacity by a great deal, but it won't improve overall performance by much.

[Matthew]

RN,

Looks to me like if used properly can yield pretty amazing results with this product.  Would it be suitable for use in a gas fired oven?  The obvious reason is that if I used the broiler at such close proximity to the top of the pizza that it would burn it in no time.  I am wondering if the same results can be achieved by placing the surface in the middle of the oven.  As far as heat up goes, Traditionally you would place your stone in the oven cranked as high as you can get it, wait for the stone to heat up & bake your pizza & then possibly place under a broiler for a few seconds.  You mention that you heat your surface by using the broiler only & leave the door slightly open so that the  broiler remains on. Will the heat that is escaping from the open door have any effect on the temperature of the Carbide Surface?  Lastly, can you cook on the surface without using a pan or will it burn the bottom before properly cooking the top?

Matthew

[November]

Would it be suitable for use in a gas fired oven?

It depends on what you mean by suitable.  With some adjustments you can use it like any other stone if you want, but the reason I started this thread was to talk about fast baking with it because that's the advantage it holds over other stones.

The obvious reason is that if I used the broiler at such close proximity to the top of the pizza that it would burn it in no time.

That's the point, or at least baking a pizza quickly is.  All things bake before they burn.  The goal is to pull the pizza out before it burns.  If you are reluctant to bake your pizza fast, this is probably not the best investment for you.

I am wondering if the same results can be achieved by placing the surface in the middle of the oven.

No.  As I alluded to in the first post, the results will not be the same.

Will the heat that is escaping from the open door have any effect on the temperature of the Carbide Surface?

Yes, but the effect depends on the oven.  I said that I kept the door barely open so that the broiler would stay on.  That is what typically happens with an electric oven.  That is not necessarily what what happens with every oven though, especially considering how gas ovens operate.

Lastly, can you cook on the surface without using a pan or will it burn the bottom before properly cooking the top?

I've never posted a picture of a pizza baked any other way than directly on the surface in this thread.  Looking just a few posts up you will see I addressed BurntEdges' question about which method(s) I have used to load the surface.

- red.november

[Matthew]

RN,
Thanks for the response, definitely makes sense.  I have sourced one locally, the thickness is 1/2" as oppose to 5/8".  Will it make a significant difference in the thermal energy?  The link is  http://www.pshcanada.com/kiln-furn.htm.  Would you happen to know the difference between nitride bonded & oxide bonded?  Which is better; or does it really matter? 

As you can see, they also sell a shelf that's Cordierite-mullite up to 1" thick.  I know that there have been quite a few past threads about cordierite, but I'm not sure what mullite is?  Would it work well as a pizza stone?  How would it compare vs. Silicon Carbide?  

Matthew

[November]

I have sourced one locally, the thickness is 1/2" as oppose to 5/8".  Will it make a significant difference in the thermal energy?

1/2" means 20% less heat capacity than 5/8".  It's only significant if you are baking two or more pizzas back-to-back.

The link is  http://www.pshcanada.com/kiln-furn.htm.  Would you happen to know the difference between nitride bonded & oxide bonded?  Which is better; or does it really matter? 

They show you that there's not much difference in density.  The oxide bonded is not as thermally conductive as nitride bonded however, but still greater than most pizza stones.

As you can see, they also sell a shelf that's Cordierite-mullite up to 1" thick.  I know that there have been quite a few past threads about cordierite, but I'm not sure what mullite is?  Would it work well as a pizza stone?  How would it compare vs. Silicon Carbide?  

Cordierite/mullite is often just sold under the label of cordierite.  I've found that asking the supplier about whether they sell pure cordierite or a cordierite/mullite combination is usually fruitless.  If they provide a data sheet, fine.  Otherwise there's not much use in worrying about it.  If you're not sure what mullite is, you can always read an article on it (http://en.wikipedia.org/wiki/Mullite).

Generically, SiC (nitride bonded in this case) has a thermal conductivity approximately 30 times greater than that of a typical baking stone.

The "30" I stated above is a rounded number based on comparing nitride bonded SiC to a generous average between Fibrament and cordierite.  Even the oxide bonded SiC you pointed out is about 20 times greater than Fibrament.  Typical baking stones and SiC aren't in the same category, so I wouldn't try comparing them to SiC more than that.

- red.november

[scpizza]

My understanding of the physics here is that the speed of the bottom bake is proportional to both the thermal conductivity of the surface and the temperature of the surface.  Thus a SiC stone can mimic the same fast bottom bake achieved from a high temperature surface in a low temperature (550F) oven.

What about the reverse problem observed in a high temperature (900F) oven?  Those cooking with ovens on self-clean find they must take extra steps to keep a Fibrament or cordierite stone temperature depressed, like covering it with foil and carefully managing timing.  If left alone to reach 900F these stones burn the bottom before the top is cooked.

It would seem a stone with a lower thermal conductivity than Fibrament (0.8 W/mK) or cordierite (2-3 W/mK) would be ideal for a high temperature oven.  Are there any pizza stone materials that would fit the bill?

I'm also wondering how wood burning ovens floored with firebricks that blend silica (0.9 W/mK) and alumina (~30 W/mK) exhibit no floor/top imbalance problems cooking at 900F.

[krup]

Never mind. You answered the last question already. 

Did you ever try using silicon carbide as a top stone in an LBE?
Did you back it w/ceramic insulation?

Regards,
Jeff

[momir]

Hi every one.My name is Momir and i am from Serbia.
I am new here but i like it very much.Good job guys.
After reading all the information about the sic surface i*v tride to gat one but it*s mission impossible back here.
So,thas enyone have some clue how to find this lovely thing in europe?
Sorry for my bad english.

[jknl]

Not to long ago my second stone broke(probably made of chamotte), after some time I found small business that specialized in building oven and oven equipment that will sell me a clay bonded SiC stone(35x33x2cm, max size for my oven). Does someone know how a clay bonded SiC stone compares to a nitride bonded or regular SiC stone?

So,thas enyone have some clue how to find this lovely thing in europe?

I found the small business mentioned above by browsing the online yellow pages by category. You could also try looking for kiln shelves made of SiC.

[pizzamatto]

There are actually several forms of "regular" SiC, but nitride bonded SiC is different in that to form it a mixture of silicon carbide and silicon additive is fired at around 2500°F in a nitrogen atmosphere; while "regular" SiC is fused into various shapes with extreme heat and pressure.

It could just be lighting.  Attached is an image of a single crystal taken from the Wikipedia article on Silicon carbide.  That is its natural color and shade.  It's like a black diamond.  Different types of ceramic bonding processes may affect the appearance as well.

Awesome stuff!   I've been personally trying to hack a micro oven inside of a bigger oven, what are the blackbody properties of this stuff.   The original poster mentions fast cooking times, is that from conductive heat from the surface or is it radiating heat at a high rate?

[skan]

Is it the silicon carbide much more expensive than the cordierite?

I've just acquired a cordierite stone and i don't like it. I thought it was going to be a stone but it looks like a brick and it feels dirty and sandy.

[buceriasdon]

In time the cordierite will become seasoned with use.
Don

Is it the silicon carbide much more expensive than the cordierite?

I've just acquired a cordierite stone and i don't like it. I thought it was going to be a stone but it looks like a brick and it feels dirty and sandy.

[skan]

I thought of oiling it, but it could not be a good idea as the oild would burn and leave some residue.

[buceriasdon]

I've never read about seasoning cordierite but nothing in the rules says you can't. I use Saltillo tiles and always season them, same as my steel plates.
Don

I thought of oiling it, but it could not be a good idea as the oild would burn and leave some residue.

[November]

I thought of oiling it, but it could not be a good idea as the oild would burn and leave some residue.

Leaving residue (seasoning) is the stated goal.  However, when burning oil you have to deal with what doesn't become residue, namely the volatile compounds which diffuse into the air.  You could just as well season the stone with sugar as I documented in the post linked below.

http://www.pizzamaking.com/forum/index.php/topic,5122.msg46827.html#msg46827

Perhaps a more interesting seasoning could be made by adding a small chunk of your favorite fermented dough to a large amount of water to dissolve into a thin liquid.  Brush the liquid on the stone and bake in the aforelinked manner.  That should get you started on the right carbon foot.