Why Pizza Steels Beat Pizza Stones (Yes, They Do)

Why Pizza Steels Beat Pizza Stones (Yes, They Do)

August 15, 2019 95 By William Morgan


A good pizza steel results in a crispier,
browner crust and superior flavor when compared
against a good pizza stone.
However, the difference is not as big as I
would have expected, and the steel still requires
a really substantial pre-heat time in order
to be at its best — about an hour, same
as I would do with a stone.
Those are the big-picture conclusions of my
head-to-head tests. I’m going to show you
my methodology and my results. But first,
let’s get clear on the underlying science.
Field trip to the big city of Atlanta and
the Georgia Institute of Technology, where
Dr. Shannon Yee does research on heat transfer.
He deals with important things, like renewable
energy technologies. We’re gonna ask him about
pizza, because: priorities.
“So, the thermal conductivity for steels,
for example, is on the order of about 14 watts
per meter kelvin. For ceramics, it’s about
four watts per meter kelvin. So, the thermal
conductivity for metal pans is about four
times higher than that for ceramics.”
This is something of which most of us developed
an intuitive understanding when we were little
kids. Think about a playground. There are
surfaces of all kinds in here: plastic, rubber,
ceramic, metal. They’re all baking in the
same sun, and depending on their color and
such, they’re all in generally the same neighborhood,
temperature-wise. But some of these surfaces
are way more hot to the touch.
In the States, you pretty much only see plastic
slides anymore, because they’re cooler to
the touch. This restored vintage metal slide
is at a watering hole here in Macon called
The Society Garden, and it works because it’s
well-shaded.
But when I was a little kid, all of us had
the experience of roasting our little thighs
on a really, really hot aluminum or steel
slide underneath the blazing hot summer sun.
That’s not because the metal slide is hotter
than the ceramic sidewalk. Their temperatures
are probably about the same. It’s because
the metal is more thermally conductive. It
transfers heat faster to things that touch
it.
BUT WHY?
“There are two dominant carriers of heat.
One, we call phonons — these are the coherent
atomic vibrations that are present in all
solids.”
Basically, when something gets hot, the particles
that it’s made out of get all shaky. And then
when that thing presses up against something
that’s not as hot, the shaky particles inside
the hot thing start to shake up against the
particles in the cooler thing, and pretty
soon all the particles are shaking at approximately
the same rate. That is phononic heat conduction.
Then, there’s electronic heat conduction — electrons
hopping from one atom to the next.
“Electrons can carry heat, right? And so,
in the case for your metal plate, you have
both phonons and electrons, because the metal
is electrically conducting. In the case for
your ceramic, that’s not electrically conducting,
right? It only has the phononic contribution.
So there’s two modes at which you can transfer
heat — through the electronic thermal conductivity
and the phononic thermal conductivity — and
the metal has both. The ceramic only has one.”
OK, so let’s go to the oven and see what this
science of this looks like in practice, but
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Now, let’s go bake some pizzas.
I want to disclose that the Baking Steel company
did send this to me for free to review. However,
they did not give me any money, and I am here
to give you an impartial assessment.
This is their basic model, it retails for
80 or 90 bucks, and weighs about 15 pounds.
Real heavy.
This stone was made by Old Stone Oven, it
weighs about 10 pounds and costs about half
as much as the steel. It has been my friend
through many adventures.
I tested the stone on Saturday and the steel
on Sunday, that way they could be on the same
rack position for every single test, and the
oven would be starting dead cold on each testing
day.
I preheated each respective surface on my
oven’s highest temperature, 550 F convection
roast. For my first test, I baked a pizza
after just a half hour of pre-heating. Here’s
the crust from the stone. Not bad, but not
great. I was expecting the steel to perform
better at 30 minutes, but look: it’s really
no better at all.
This may be in part because that particular
steel is 50 percent heavier than that particular
stone, so even though steel conducts heat
better, the extra mass just needs extra time
to heat up. At 30 minutes, that test is a
wash.
Indeed the Baking Steel directions do advise
pre-heating for 45 minutes to an hour. So
let’s try this test again after 60 minutes
of pre-heating.
There’s the stone pizza after an hour of pre-heating
— nice brown cornice and the bottom crust
is even dark brown. Really nice.
Now, here’s the steel pizza after 60 minutes
of pre-heating. Look at those extra brown,
almost black spots. We’re verging on burned
there, and I think that’s good.
The appearance of little black burned spots
on pizza is known as “leoparding” or “leopard
spotting,” and it’s widely viewed as a desirable
trait. It’s arguably a defining feature of
Neapolitan-style pizza. I’ve never achieved
true leoparding on a home oven, but we’re
getting close there.
To be clear, this is not just about cosmetics;
this is about taste. The steel at 60 minutes
produces a noticeably crispier texture and
a superior flavor. Extreme temperatures cause
chemical changes — not only in the crust,
but I think in the sauce and cheese layer
as well — changes that make pizza taste
like more than just bread and sauce and cheese
and top of each other, which how how these
pizzas tasted after 30 minutes of preheating.
In comparison, after 60 minutes, that is starting
to taste like pizza — greater than the sum
of its parts.
I want to note that after 60 minutes or preheating,
my stone here did a really good job compared
to the steel, especially if you value evenness.
Look at that totally even coat of brown. One
explanation for this might be that I’ve been
using this thing for well over a decade. It
is very well-seasoned, or has a really good
cure on it. What that means is that the oil
of thousands of pizzas has gotten super, super-hot
on this surface and it has polymerized. Dr.
Yee told me that polymerized fat layer isn’t
especially good at conducting heat per se,
but it is a a really excellent thermal interface.
What that means is that it’s really good at
kind of reaching up into the irregular bottom
of the pizza and filling up all the little
cracks and conducting heat to them.
My new steel might get better in that regard
too as it develops its own cure over time
and use.
For my third test, I wanted to see what would
happen if I turned around and baked another
pizza right after I baked that first one after
a 60-minute pre-heat. I’m not gonna blow all
this time and electricity on one pizza. I
have to be able to bake two in a row.
Yes, this one is gonna be a white pizza, and
yes, that recipe is forthcoming.
Here’s the one from the stone, and you can
see how much heat the stone lost baking the
previous pizza. That is not as good.
Here’s the equivalent pizza on the steel,
and yikes that stuck pretty bad to the peel.
Oh well, I guess it’s going to be amoeba-shaped.
There’s the crust, and look, that is not as
good as the previous pizza from the steel,
but it beats the one from the stone, for sure.
I’m sold. I did not observe the really dramatic
difference that other reviewers have noted,
but definitely, if you can get a big, heavy
one — more heavy means more mass, more heat
— a pizza steel does absolutely beat a pizza
stone for most purposes.
I’m still gonna keep my old stone buddy around,
though. For certain things like thicker breads
or thicker-style pizzas, you might want something
that conducts heat a little bit more slowly.
Otherwise, the bottom will be burned before
the rest of it is baked through.
But for New York-, California- or Neapolitan-style
pizza being baked in a home oven, the choice
is clear. Steel beats stone.