pizza stone and the oven
when i bought my pizza stone ( at sur la table) i think i remember the sales person telling me that if i keep my stone in the oven it can regulate the oven temprature and also make the temprature even in the oven. can anyone confirm this or did i just dream this? i called sur la table this morning and the person had no idea what i was talking about.
I read this somewhere too - have no idea if it's true or not. I keep my stone in the oven all the time mostly because there is no reason not too. (It's been in there for over 6 years and it's still going strong.) But I can't say I ever noticed any difference in my oven's performance.
Wow, lots of thermodynamics questions on CH.
So once again, I dont know anything about cooking, but I know a little bit about
There are two issues here:
1. heat capacity
2. surface area
Having an object with high heat capacity in your oven will probably stabilize the
temperature in the same way that having a a full refridgerator or a full ice chest/cooler
will stabilize the temp inside and make it less prone to temp swings when you open
the door etc. I think using the word "regulate" here is misleading. Or another analogy
is one reason to use a lot of water when cooking say pasta is you dont want the
temp of the boiling water to go down a lot when you add the cold/room temp pasta.
That would make the cooking time less predictable. A pizza stone will stay a more uniform
temperature than a 1mm thick metal pizza pan placed on a rack after you put the pizza on it.
Note: this temperature stabilizing aspect would apply as wel; if you just put a
"preheated" canonball at the botton of your oven too. it's like putting a cold gallon
of milk in the fridge. It's te heat capacity (and shape ... see surface area discussion
below], not anything magical about the pizza stone.
A full discussion of surface area is beyond the scope of this post [and franky a little
beynd my ability to speculate beause although understand how to model the heat
aspect, i dont know enough about cooking to figure out the nuances of convection vs.
conduction, when it comes to oven cooking], but having a heated pizza stone in your
oven effectively changes the surface area-volume ratio. note that a wide and deep
"brick shaped" pizza oven has different surface-volume ratio than a cube-shaped oven.
and of course a smaller oven has a higher surface:vol ratio than a larger one ... adding a
pizza stone effective increases the surface area, so it is probably simpler to have a hotter/
more uniform temperature [i am assuming you dont have an oven with forced convection].
Good scientific analysis. I just listened to Shirley Corriher who recommended the pizza stone for keeping a more uniform temperature and that that would be more important than switching the cookie sheets in the middle of baking which would affect the oven temperature too much. So, I keep my pizza stone in the oven and don't switch the cookie sheets. It's worked.
That was really interesting, psb, and piqued my curiosity...because the same chef friend who told me my cast iron griddle would make a viable range-top diffuser also suggested I try using it (or a cast iron skillet, for that matter) as a "pizza stone".
I tried it, and, lo and behold...success. Which I think would tend to validate your points re the surface area *and* the cannonball. So now I use it anytime I want to turbocharge the oven. No scientist here, myself, but I think it might also help with heat retention, if I'm cooking something I need to open the door frequently to baste, poke, etc.
This is starting to make me thinks of a product idea:
say you have the caricature "bachelor's fridge" with a six pack of
beer, a jar of mustard and nothing else. And say our Bachelor is
also a Green who cares about wasting energy. I could sell you a giant
balloon you could inflate which would take up say the top 80% of the fridge,
making the fridge much faster to re-cool after you open the door and thus
more energy efficient ... *it in effect makes the fridge smaller* ...just like the
"canonball theory" makes an oven smaller. Or, I suppose you can just
recommend our Bachelor keep 5 cases of beer in there instead of a sixpak.
Anyway, re: cast iron as a diffuser ...
Again I dont know anything about cooking, but how well something works as a
diffuser will depend on 1. the inherent conductive properties of the material
2. the shape of the object. In the cast iron case, iron isnt the most conductive
of materials, but the much cheaper price
(compared to copper, let alone diamond -- I assume it is not common knowledge
that diamond is about the best heat conductor out there. You think your Mauviel is
expensive, wait for the DeBeers line of Forever Cookware. See e.g. http://en.wikipedia.org/wiki/Material_properties_of_diamond#Thermal_properties
makes it viable to have it be much thicker. So the geometry offsets the lower conductivity.
I glanced at my copy of MCGEE ... obviously that book -- and the process of
cooking --- is more chemestry than physics, but there is an ok discussion about
some of this stuff on pp780-791. Again, apropos to what goes on in the kitchen, the discussion is mostly set in the context of heating rather than freezing/cooling. But he
uses somegood examples like "why is it faster to boil a potato than to bake it", and
some theoretical stuff like a discussion of the the parition of energy -> raising the
boiling temp of water with salt, and pratical things like how does a pressure cooker
I keep mine in the oven.
It's fairly large, thick and square. Made of some sort of reasonably dense ceramic material. (This one, I think: http://www.amazon.com/Old-Stone-Oven-...)
I suppose being slow to heat, and slow to cool off, it probably does help maintain more even temperatures in the oven, but I've done no investigation to confirm this.
I have an electric oven of the common sort, not very expensive. Here's what I have found:
(1) It takes a little longer to preheat the oven. Say, 15 minutes instead of 10.
(2) Things bake more evenly. With the exposed heating element at the bottom of the oven, breads, cakes, cookies and that sort of thing had a tendency to get too brown or scorch on the bottom, unless watched very carefully. That no longer happens. I think this might be because the stone intercepts the direct infrared radiation ("heat rays") from the exposed element, which would overheat the bottom surface of my bakeware, and instead converts it to hot air. Or maybe it's just me that's full of hot air...
(3) Things take a little longer to bake, say, maybe 33 minutes instead of 30.
(4) Things like cupcakes and muffins that should have nicely rounded tops come out a bit flatter, because they aren't baking as quickly. Turning up the heat by 25 degrees or so resolves this, if it's an issue. See Shirley Corriher's "Cookwise: The Secrets of Cooking Revealed " for an explanation of both these phenomena.
(5) Any fat or fatty substance that gets on the stone soaks in and smokes. Forever. So I have learned to keep a sheet of foil over it when I'm not baking directly on the stone.
(6) Other than those specific points, it doesn't seem to make much difference.
On the whole, I like it quite a bit. I think my mid-price electric oven does a noticeably better job with the stone than without. In a higher quality oven that heats more evenly to begin with, or in a gas oven where the heating "element" isn't exposed, the stone might not make so much difference. I don't imagine it would make any difference at all in a convection oven.
Wow. thanks guys! i'll be keeping that guy in the oven. i did notice it takes longer to heat. i have a brand new bottom of the line gas oven (thanks landlord!) which i'm sure is convection. i got my own thermometer in there now. i'mm concerned since i'm a big baker. i'm also getting big from having too much time and making too many treats! with the upcoming holidays i'm going to be making a stab at some desserts on the first try. my last oven which i believe was from the 70's ruined cakes b/c it couldn't keep a stable temp. i'm just being overly conscious.
I think you are ok, but I don have one concern, based on experience I've had.
If your stone is large, relative to the size of the oven, I think the temperature tends to stratify a bit, with the heat from below being trapped under the stone (the baking element), and the oven gets a bit uneven. If the stone is smaller, this seems like less of an issue, and if you are on convect, the fan moving the air around seems to solve for this too.
Anyone else have this experience?