Silicon Carbide Baking Surface

[November]

Silicon Carbide Baking Surface

I first proposed using silicon carbide (SiC) as a baking surface material back in December 2006 (http://www.pizzamaking.com/forum/index.php/topic,4215.msg35417.html#msg35417).  Since then there have been a few more mentions of it, but nobody really picked up the ball and ran with it (to my knowledge), so recently, after finding a supplier that offered a decent compromise between the properties I was looking for and price, I purchased a silicon carbide shelf to use in my unmodified electric home wall oven.

To use such a material for baking in a basic electric home oven, the material has to be placed in close proximity to a source of radiant heat so that the top and bottom of the pizza bake at the same time.  This is accomplished in the setup I have by situating the top surface of the SiC shelf 6 cm from the bottom of the top heating elements.  In other words, I have a 6 cm clearance for the pizza.  To maximize efficiency, I use only the broil setting, which for my oven is actually consuming less energy than the bake setting.  That's why my broiler is not that great but the oven can reach over 600°F when baking.  Modern electric ovens should be able to surpass what my oven can turn out, but the pizzas are going to finish fast on the SiC surface in any case.

The bake times I have reported thus far (90 s, 120 s, and a burnt 113 s) pretty much tell the story about how much faster SiC conducts heat than a typical baking stone.  The pizza that burnt in 113 seconds (picture attached) was part of an experiment to increase the baking surface temperature to above 700°F just to add a little extra energy to play with.  This is also pretty easy to accomplish in most ovens by leaving the oven door open so that the thermostat doesn't turn the broiler off.  It's completely unnecessary, but I did it to drive the point home about super fast baking in a basic home oven.  Based on my calculations, I should have pulled the pizza out in 82 seconds for a perfect bake.

Generically, SiC (nitride bonded in this case) has a thermal conductivity approximately 30 times greater than that of a typical baking stone.  Of course that doesn't mean baking is 30 times faster, as the pizza will have something to say about how fast it will receive the transferring energy.  It does mean baking can be made as fast as you want, and faster.  It also means preheat times are faster.  It only takes about 15 minutes to reach 550°F in my oven, and a few minutes more with the oven door open gets it to over 700°F.  The physical properties, price, and location of purchase for my SiC shelf are:

Dimensions: 16" x 16" x 0.625"
Weight: 6.464 kg
Price: $127.25
http://www.seattlepotterysupply.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=31257&Category_Code=HASCS

In addition to the picture of the burnt pizza, which I don't intend to duplicate, I will post more pictures as I continue to use the SiC shelf.  Also included in this post is a picture of the actual SiC shelf I'm using.  The thermal properties of SiC notwithstanding, it is a beautiful material.

- red.november

[Essen1]

RN,

I'm wondering how it would perform in the LBE? It might be too much heat for the pizza to handle.

The link you posted, that's the same company I called to inquire about the ceramic coating.

[November]

I'm wondering how it would perform in the LBE? It might be too much heat for the pizza to handle.

It would make a great top stone, but you would have to find a lower sweet spot with regard to heat to use it as a bottom stone.  Your grill's output is adjustable, so I don't see why you couldn't pull it off.  So your preheat time might be 5 minutes instead of 15 minutes.  I don't think that would be anything to complain about.

- red.november

[Essen1]

RN,

I was thinking the same thing about using it as a top stone. I'd have to find someone who could cut it into a round shape.

It would probably take me a few pies to determine the sweet spot, but since I'll be able to raise and lower the stone at will, that shouldn't be hard to find out. And shorter heating times means even more savings on fuel. Any idea how the SiC stone and the ceramic insulation would work together? I could imagine that the combo would turn the LBE into a blast furnace, heat-wise. 

What about the SiC as a bottom stone?

[Essen1]

Never mind. You answered the last question already. 

[November]

I could imagine that the combo would turn the LBE into a blast furnace, heat-wise. 

Actually what you just described is essentially a kiln: ceramic insulation and SiC shelves.  Like you said, if that's the route you decide to take, you will have to be more conservative with the heat.  I'm sure that won't be a problem.

- red.november

[Pete-zza]

November,

Is the SiC baking surface porous and therefore able to absorb moisture from the dough to increase the crispiness of the finished crust? And will you have to modify your existing dough formulations to work with the new baking surface?

Peter

[November]

Is the SiC baking surface porous and therefore able to absorb moisture from the dough to increase the crispiness of the finished crust? And will you have to modify your existing dough formulations to work with the new baking surface?

I think the picture shows that it's porous.  It's actually the most porous stone I've ever handled, much more so than cordierite.

I don't think you have to modify existing dough formulas to work with SiC.  In the first batch where I baked the pizzas in 90 and 120 seconds, the only modification I made was to lower the amount of malted milk powder and raw agave nectar; but even after modification it was within the range most people use those type of ingredients.  The pizza that burned had only flour, water, salt, and ADY, so the possibilities are just as endless.

- red.november

[Essen1]

Peter,

I could imagine that one would have to adjust at least the hydration level. But come to think of it, maybe not, since the baking time would be significantly shorter.

Just thinking out loud.

[November]

Peter,

Is the SiC baking surface porous and therefore able to absorb moisture from the dough to increase the crispiness of the finished crust?

It isn't obvious from the photo in the link bellow, but when I turned the pizza up to take a picture of the bottom, the crust snapped in half as a result of its crispiness.

http://www.pizzamaking.com/forum/index.php/topic,2083.msg60468.html#msg60468

Attached is a picture with more detail of the bottom of an unassuming pizza baked in the same way as the batch linked above, but with the same simple ingredients as the 113-second carbon discus.  It finished in under 2 minutes.

- red.november

[Pete-zza]

Based on my calculations, I should have pulled the pizza out in 82 seconds for a perfect bake.

November,

Out of curiosity, can you tell me how you calculated 82 seconds as the right time to yank the pizza from the oven?

Also, do you think that you will migrate to the new SiC baking surface for most of your pizza making and, if not, why not?

Peter

[November]

Peter,

Out of curiosity, can you tell me how you calculated 82 seconds as the right time to yank the pizza from the oven?

Also, do you think that you will migrate to the new SiC baking surface for most of your pizza making and, if not, why not?

The batch that included that pizza also included two pizzas that came out of the oven in just under 2 minutes that baked just fine, which is why I waited until just under 2 minutes for the third pizza.  As I explained before though, the third pizza was baked for the superheated trial.  I measured the heat transfer rate of the two states (controlled and superheated) and multiplied the quotient by 113.

I will use the SiC surface for all my "stone" baking since it is a very efficient method of baking a pizza.  The amount of energy I consume baking two pizzas using my perforated pan and a 20-minute preheat is 5712 kJ.  The amount of energy I consume using SiC and a 15-minute preheat is 3420 kJ.  It's evident that energy is being conserved when I can stick my hand in the oven bellow the stone at full blast and keep it there without getting burned.

As for taking the place of my perforated pans, I don't think that will happen to any great extent.  Often times I need to make quite a few pizzas right when guests arrive, and pans make that very convenient by allowing me to have the dough shaped and stacked in advance.  I also happen to like the texture of pizzas baked a little slower.  It's the kind I grew up on, and the kind most of the friends I have appreciate.  I don't usually get a lot of use out of a stone when I have friends over.

- red.november

[Engineered Ceramics]

Any interest in trying out a Fused Silica baking surface?

Not quite as conductive as SiC, but also less expensive. 

We have a 15" x 15" x 3/4" tile that typically sells for around $50 + shipping.

It weights about 12 lbs.

It is also nearly impervious to thermal shock.

[November]

Any interest in trying out a Fused Silica baking surface?

Not quite as conductive as SiC, but also less expensive. 

Bill,

I'm not sure why anyone would want a material that's about half as conductive as a typical pizza stone.  "Not quite as conductive" is an understatement to say the least.

- red.november

[November]

Here are some pictures of tonight's pizzas baked on SiC.  I pulled all three pizzas out at 105 seconds.  The one picture of the bottom is typical of all three pizzas.

- red.november

[November]

... more pictures ...

[scott r]

this is amazing!  Do you have to use the broiler to get the top to cook as fast as the bottom?

[November]

Do you have to use the broiler to get the top to cook as fast as the bottom?

I don't know if you're asking in general, or specific to my oven, but in my oven probably not.  I'm using the broiler in my oven because it's more efficient.  There's no point in heating the air bellow the stone.  It all comes down to the amount of radiant energy reaching the pizza from the top.  Some ovens can probably achieve this using the bake setting, others might have to rely on the broil setting.

Are you asking because you don't have a broiler?

- red.november

[Essen1]

RN,

I found them a little cheaper at the company I ordered the ceramic fiber blankets from. But I don't think they are as thick as yours. They also offer them in "round" or for round kilns, but unfortunately not in the size I'd need.

http://www.axner.com/axner/equipment/nitride-bonded-shelves.php

[November]

I found them a little cheaper at the company I ordered the ceramic fiber blankets from.

Mike,

When considering the cost per basic unit of measure before shipping, they are not any cheaper.  Axner offers their SiC shelves at $0.528 per cubic inch, and Seattle Pottery offers their SiC shelves at $0.498 per cubic inch.

- red.november