Pizza Making Forum

Pizza Making => General Pizza Making => Topic started by: TXCraig1 on May 10, 2015, 09:16:08 PM

Title: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 10, 2015, 09:16:08 PM
Episode 1 - Do pizza stones absorb moisture from a pizza while it bakes?

Like the claim that NYC water makes better pizza, say something enough and people will believe it. Say it a few more times, and they will refuse to listen to anything to the contrary. To this end, there is no shortage of people who believe pizza stones absorb moisture from the pizza as it bakes. It's hardly surprising, a quick Google search turns up dozens, if not hundreds of websites that all say something to the effect: "Pizza stones are made of porous materials to absorb moisture easily." (http://www.foodservicewarehouse.com/education/how-to-use-a-pizza-stone/c31723.aspx#sthash.w7cgmKKE.dpuf) Even Wikipedia, the poster child for 'you can't put it on the internet if it isn't true' gets in on the action. Seven websites promoting the myth are listed here: http://www.pizzamaking.com/forum/index.php?topic=28243.msg379789#msg379789.

Manufacturer,s such Breville for example, use the myth to try to sell product: "The pizza stone's porous surface absorbs moisture from the pizza dough, resulting in a crisp brown pizza crust." (http://www.brevilleusa.com/13-pizza-stone.html). This site that purports to be a pizza stone buying guide and namer of the best pizza stone for 2015 talks about a pizza stone absorbing moisture four times: http://thoroughlyreviewed.com/home-kitchen/pizza-stone-review/

Of everything I read this afternoon however, I found this bit on Serious Eats to be the most interesting:
Quote
"The point of using stone or ceramic instead of metal is that the stone absorbs moisture from the dough, resulting in a crisper crust. So, glazing sounds like a bad idea, right? According to packaging description, the glaze is "micro-crazed" which sounds a lot like my mental health some days, but it actually means that the glaze has teeny cracks, so the stone can still absorb moisture." http://slice.seriouseats.com/archives/2011/04/pizza-protips-baking-surfaces-part-6-emile-henry-pizza-stone-review.html

Perhaps at the time, it said this on the Emile Henry Website, but it doesn't today, "The glaze is micro-crazed contributing to crispy well-baked crusts, just like a pizza oven." I don't see anything about absorbing moisture. It would seem that the Serious Eats author is so programmed to believe the myth that she automatically assumed this is what the manufacturer was talking about (maybe they were) and then proceeds to imagine and explain how it works!

So what is the truth? Does a pizza stone absorb moisture as the pizza bakes?

Common sense seems to suggest NO. At one atmosphere, the density of steam is about 0.6kg/m^3 or 0.006g/cm^3. Say you have a typical decent stone (0.5" x 16" x 14"), that would be 1,835cm^3. The mass of steam/water at normal operating temps that could occupy that volume if there was NO stone is 1.1g. Now consider that probably 99+% of the volume is stone and assume there is 1% open space, if it was fully saturated, the stone could hold 0.11g water. That's the MAXIMUM possible; I'd guess that the water absorbed from a pizza by the stone is meaningfully less than 0.01g.

Simple physics also seem to suggest NO. The Ideal Gas law Tells us that PV=nRT (the letters represent Pressure, Volume, amount (in moles), ideal gas constant, and Temperature of the gas, respectively). In simple terms, as temperature increases, if there is nothing to contain the gas, pressure will remain more or less constant and volume will increase - or vice versa at a constant volume. Let's say some steam or water vapor enters the stone from the pizza; unless the stone is cooler than the pizza, the temperature of the steam/water vapor will increase. Since there is nothing containing the steam on the top side of the stone, the volume of steam will increase and pressure will remain more or less constant. The net effect is that most water that enters the stone will be forced OUT.

I also did a couple experiments to test if the theory is supported by real world observations. My pizza stone is to heavy for my scale to weight with 0.1g precision, so I took a solid brick with a pore structure that looked similar to, if not a bit more open than my pizza stone, and broke it in half. I weighed both halves and then put one half in the oven at 475F for an hour and submerged the other in a sink full of water. The piece in the sink gained about 5.7g while the piece in the oven LOST 41.1g. There was some moisture in the brick, and it was forced out as the temperature increased exactly as the theory predicted. If moisture in the stone is being forced out, what are the chances it is going to absorb moisture from a pizza? At this point, I was pretty sure thee myth was dead, but I pushed on.

In the next test, I placed 5ml (5g) water on the stone, closed the oven door, waited 30 seconds, then weighed the stone. It gained 0.1g that dissapeared within the next 30 seconds. I then put another 5ml water on the stone and placed two corn tortillas right on top of the water to try to trap some in the stone. Again I waited 30 seconds and weighed the stone. Like the first test, it gained 0.1g that dissipated in the following 30 seconds.

Lastly, I made a simple 65% dough from flour and water only and baked a small pizza analogue (80g, 5", TF=0.14) for 7 minutes. The stone actually lost 1.4g in the process. Not only did it not absorb any moisture, it forced more previously trapped moisture out just as I would expect from the theory. For the final test, I put 5ml water on the stone and baked another pizza on top of it for 8 minutes. The stone gained 0.1g, however the pizza stuck badly to the wet stone, and some, if not all, the additional weight was crust stuck to the brick.

Bottom line, there is nothing - not common sense, not theory, and not experimental results - supporting this myth being true.

This myth is

Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 10, 2015, 09:22:17 PM
I put the wet half of the brick in the oven when I was done, and within the first 10 minutes, it had not only lost the 6.4g it gained after a total 2 hours of soaking but also another 4.9g that was in the brick before soaking.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 10, 2015, 09:25:06 PM
The data:

Title: MythBusters - Pizzamaking Edition
Post by: David Esq. on May 10, 2015, 09:46:17 PM
Oh, but what if the stone is drawing out the moisture of the wet dough only to have it vaporize once it does so? No need for the water to actually occupy the stone for long.

I thought I recalled that most mass is made up of empty space. So maybe that stone is 99% empty space and only 1% stone.

Props to you for running the experiments. The only thing I am truly critical of is the suggestion that atmospheres and common sense being uttered in the same sentence.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 10, 2015, 10:15:48 PM
Oh, but what if the stone is drawing out the moisture of the wet dough only to have it vaporize once it does so? No need for the water to actually occupy the stone for long.
I saw some websites that seemed to suggest that though I'm not sure most of them perceived a difference when writing. At least one cited "capillary action," however that is a phenomenon involving liquids - not gas. By what mechanism would the water be drawn out, in quantities larger than trivial, that would be any different than baking on a cast iron pan or steel? The moisture in question is a gas - not a liquid - and an expanding gas at that. Moisture is trying to exit the stone, not enter it.

Quote
I thought I recalled that most mass is made up of empty space. So maybe that stone is 99% empty space and only 1% stone.
Maybe at the subatomic level or something like that, but water can't flow into that space. In the sense that "empty space" matters here, it's pretty much stone. Besides, it didn't absorb a whole lot of water as you can see in the table above.

Quote
The only thing I am truly critical of is the suggestion that atmospheres and common sense being uttered in the same sentence.
I don't understand this comment?
Title: Re: MythBusters - Pizzamaking Edition
Post by: rparker on May 10, 2015, 11:01:00 PM
Interesting, Craig.

I wonder if there is a humidity level in the heat radiating from various cooking materials that is different enough from one another to matter?  Something, somewhere gave someone the idea that water was being drawn out.

One day not too long ago, I was doing a bake on my stock BS stone. For whatever reason, I lifted the pie and saw an area perhaps an inch by 2 inches steam for a second or two. The steam at that point was coming from the stone surface. The stone surface even had what looked like a shade darker in that one spot. then as fast as I saw it, it was gone along with the steam. Never seen this before or since. It was not a long time into a bake. Maybe 30-60 seconds.

I'm not going to suggest the stone attracted water. All's I'm saying is that moisture hit the stone and the stone did not want to keep it. My half-witted theory is that the crust would have let the steam from the surface pass the first chance it got. You've seen plenty of pics of my pies. They are rather moist from watery sauce, excessive pepperoni and boiling cheese grease. Not surprising at all moisture got to that spot.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 10, 2015, 11:59:25 PM
Something, somewhere gave someone the idea that water was being drawn out.

Yup, and it's the same story for about a million other things that turned out to be false. There is no doubt that the stone is porous and absorptive. You put some water, or pretty much any liquid on it for that matter, and it will soak in - so it must absorb moisture from the dough, right?  Wrong. We're not talking about a liquid. We are talking about a gas - an expanding gas. 

My guess about your mystery pie is that it had a small hole in it.
Title: Re: MythBusters - Pizzamaking Edition
Post by: David Esq. on May 11, 2015, 04:40:12 AM
If you add water to a hot skillet it dances around a bit before vaporizing.

I wonder, if you do this to a hot stone, will some of the water be absorbed temporarily before it vaporizes?

If you throw a wet blanket on a hot stone (like a pizza dough)  will it for sure go from damp to steam without transitioning any moisture to the stone before being expelled out as steam? Maybe the brief initial period of time when  there is less moisture in contact with the dough means something.

Note: I assume that the success of baking steel pretty much demonstrates that porousness of the material is not a positive characteristic. That is what I would characterize as a common sense conclusion. What you had indicated was more of a scientific approach requiring knowledge that isn't at all common. 
Title: Re: MythBusters - Pizzamaking Edition
Post by: RobDude on May 11, 2015, 07:14:19 AM
I'm at a very novice level of pizza making - just following recipes formulated by others without really understanding much.  I also believed the 'drawing moisture' out of the crust (because I'd read it online).

My probably silly question, if you don't mind my asking, is - what's the benefit of a pizza stone?  I have one, and I've seen a few recipes that say to cook on a stone.  If I preheat a regular/cheap aluminium pan in the oven at 500F, what will the difference be to a stone preheated to 500F? 
Title: Re: MythBusters - Pizzamaking Edition
Post by: Crispy Please on May 11, 2015, 07:28:54 AM
I'll add a little anecdotal observation to the excellent science provided by TXCraig1.

Most forum members who bake pies in their home ovens report much better results with a baking steel than with a baking stone.

How much moisture do you think steel absorbs? :o

-Crispy
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 09:22:45 AM
If you add water to a hot skillet it dances around a bit before vaporizing.

I wonder, if you do this to a hot stone, will some of the water be absorbed temporarily before it vaporizes?

If you throw a wet blanket on a hot stone (like a pizza dough)  will it for sure go from damp to steam without transitioning any moisture to the stone before being expelled out as steam? Maybe the brief initial period of time when  there is less moisture in contact with the dough means something.

No need to wonder, I saw it yesterday. If you put enough water directly on a stone, some gets temporarily absorbed. Initially, water dances on the stone just like on a skillet. Once you have added enough to drop the temp of the very outermost layer below 100C, you see some absorb before it quickly hits higher temps below and also the heat below moves to replace heat at the surface turning the water to steam and forcing it back out.

The difference however is that a wet blanket is not an analogue for pizza dough. This can be demonstrated by a very simple experiment: squeeze a wet blanket and water will come out. I don't care how hard you squeeze pizza dough, you are not going to get a single drop of liquid water to come out.

There is no doubt that a porous surface can draw moisture out of dough given suitable time; we see it happen in wood dough boxes. However this is demonstrated over the course of hours at room temperature - not minutes at hundreds of degrees. I suspect stone would draw moisture out of dough in the same way, but given the slow water transfer rate and rapid heat transfer rate, it would seem that what tiny amount of water there is at the contact surface would turn to steam before it could be absorbed.

Quote
Note: I assume that the success of baking steel pretty much demonstrates that porousness of the material is not a positive characteristic. That is what I would characterize as a common sense conclusion. What you had indicated was more of a scientific approach requiring knowledge that isn't at all common.

Maybe; however I'm not sure you can necessarily draw that conclusion. From what I've seen, it would appear that the success of steel as a baking surface at moderate temperatures is largely a result of higher thermal conductivity (the difference in thermal conductivity is the same reason stone is vastly superior at higher temperatures). As far as I know, nobody has tested a porous surface with similar thermal characteristics. While it may not be positive, I don't have any reason to think it's a negative. My gut feeling is that it doesn't matter much one way or the other. One tiny, untested bit of evidence supporting this, despite the glaze of the Emile Henry pizza stone being "micro-crazed" whatever that means, I suspect if you put some water on it, it would act like its non-porous, and from the SeriousEats link above, it appears it performs similarly to unglazed stones. 
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tscarborough on May 11, 2015, 09:27:46 AM
That is actually a concrete paver, not a brick.  It has an absorption rate of around 5% so at a weight of 6#, it could under test conditions absorb about 8.4g of water.

None of that has anything to do with your test, it is just provided as background.  I have never heard the stone absorbing water theory, but it makes no sense on the face of it.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 09:41:45 AM
My probably silly question, if you don't mind my asking, is - what's the benefit of a pizza stone?  I have one, and I've seen a few recipes that say to cook on a stone.  If I preheat a regular/cheap aluminium pan in the oven at 500F, what will the difference be to a stone preheated to 500F?

As compared to a thin aluminum pan, the main difference is the amount of heat that can be stored. Think of a pizza stone like a heat battery. It functions very much like an electricity battery.  You load it up with heat over a long period of time - we call this pre-heating and it's analagous to charging a typical battery. In both cases, we are loading energy into something.  Once the battery is charged, we can use it to do work. In our case, the work is baking pizza. A stone is much more conductive than air. When baking on a pan, you have a tiny bit of stored energy, but once it has transferred to the pizza, that energy can only be replaced as fast as it can be transferred in from the sorrounding hot air and thermal IR coming from the oven walls. With a stone you have a lot more energy that can be transferred quickly to the pizza. A stone can deliver energy to the pizza faster than the dough can transfer the delivered energy throughout the pizza therefore the temperature quickly increases at the interface creating a nice crispy browned crust.

One of the reasons that steel works well is that it transfers heat >10x faster than a typical stone. This allows you to use intense heat from a broiler to quickly bake the top as the steel quickly bakes the bottom. The benefits of quicker bake times is a much larger discussion.

There are three main factors that matter with respect to the baking surface:

1) Thermal conductivity - how fast can the material discharge (and absorb) heat.
2) Specific heat capacity - per unit of mass, how much heat can the material hold. It can vary a lot. 1kg of brick can hold ~2X as much heat as 1kg of steel. However, steel is denser, so 1kg of steel is smaller than 1kg brick
3) Mass - more mass = more potential stored heat. This is why people often seek out thicker stones or steel. There are deminishing return however. More mass also takes longer to heat and weighs more. At some point, the downside outweighs the added heat storage capacity.

Title: Re: MythBusters - Pizzamaking Edition
Post by: PrimeRib on May 11, 2015, 10:27:54 AM
Thanks for testing. I appreciate the science of cooking. I wonder if anyone has tried a Blackstone pizza with no stone, just the metal tray. I know just the stone has been tried. 
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 11:15:09 AM
I wonder if anyone has tried a Blackstone pizza with no stone, just the metal tray. I know just the stone has been tried.

I doubt it has been tried. If I look in my crystal ball, I see black on the bottom and white on top.

Conductivity can't be considered in isolation. Temperature, location of the heat source, heat balaance, conductivity, mass, insulation, etc. all work in concert.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Bobino414 on May 11, 2015, 01:44:06 PM

Probably not absorption but..........

To start off I agree there is no absorption of water into the stone.  But there must be an explanation for why the bottom of the pie(using HG flour) bakes so much better on a stone (think even toasted and darkish) compared to metal (blond to light brown). 

A few years ago I did an experiment in my deck oven.  The top shelf had a Cordierite stone while the bottom deck had a Cordierite stone with an aluminum baking sheet on top.  The oven was heated  to 600+ degrees and a pie was launched on each deck.  When the pies were pulled about 4 minutes later the pie in direct contact with the stone was properly baked while the pie on the aluminum surface showed the expected blond crust which I thought was due to trapped steam. 

So my best explanation is that the porous stone allowed the steam to escape laterally so there was no dough tenting thus an even bottom bake.

I guess people that put forward the thought that the stone absorbs moisture are using "stone absorption" as a convenience term but isn't the effect the same?
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 02:47:17 PM
Bob,

A couple thoughts on those observations;

- with respect to putting a metal pan on top of a stone, you create an air gap in the process which could have a significant effect on heat transfer. Unless you have a way to laminate the two, I'm not sure you can infer much from the test. If it were the case that baking on metal was a problem, why has steel plate been so successful? I still think it's largely a function of heat transfer not surface texture.

-there may be something to the idea that the texture on the stone provides a path for the steam to escape though I've seen plenty of bubbles form under the dough on a stone.
Title: Re: MythBusters - Pizzamaking Edition
Post by: mitchjg on May 11, 2015, 06:53:20 PM
Craig:

I have a suggestion for a future episode of MythBusters.  "You cannot maintain a sourdough starter different than that produced in your area"

Here is an example of a random web hit:

"Some places, San Fransisco for instance, are well known for their local starters. You can buy San Fransisco sourdough starter online, but your bread will only taste like San Fransisco Sourdough for a few days or a couple of weeks. If you keep that starter alive, it won't take long before it takes on local yeast and bacteria and creates bread that tastes like the sourdough made by everyone else in the neighborhood."






Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 07:12:50 PM
NY water might be easier.  :o
Title: Re: MythBusters - Pizzamaking Edition
Post by: mitchjg on May 11, 2015, 07:18:10 PM
NY water might be easier.  :o

I was hoping you would have a quick and easy experimental design in your back pocket that would make it easy.  Sigh...
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 07:52:07 PM
We might be able to think of something.
Title: Re: MythBusters - Pizzamaking Edition
Post by: PrimeRib on May 11, 2015, 09:54:57 PM


I have a suggestion for a future episode of MythBusters.  "You cannot maintain a sourdough starter different than that produced in your area"

I wonder why no one has attempted this to date? There are clearly two different camps of opinion here, and it would be interesting to see this issue decided one way versus the other.

Title: Re: MythBusters - Pizzamaking Edition
Post by: mitchjg on May 11, 2015, 10:12:11 PM
I wonder why no one has attempted this to date? There are clearly two different camps of opinion here, and it would be interesting to see this issue decided one way versus the other.

Seems like it is probably very difficult.

I am not sure if anyone on the forum has the laboratory apparatus that would enable prevalence and identification of different yeasts and bacteria, etc.  Perhaps there are proxies for enabling the declaring of "different" such as fermentation rate or PH under identical conditions.  I know I do not know enough about the food science to know.

My impression is one camp of opinion is based on "I read it somewhere on the web, so it must be true."  My impression of the other camp is "it tastes different, smells different,  and it behaves different in fermentation/rise, so it is different."  I am in the latter camp based on experience and the reasoning I have thought through (accurate or inaccurate as it may be).  Both bases can be fraught with error but I personally have big trouble with blogs feeding blogs, etc. as a basis for much.

Maybe blind taste testing and baking testing would do the trick.  2 cultures, supposedly different.  Randomize the baking with each and randomize the tasting with each.  Statistical measures would then help determine if there are differences that are significant or not - i.e. if it bakes different and it tastes different, it is different.



Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 11, 2015, 10:22:04 PM
It's in interesting topic. We have had members convinced beyond and doubt on both sides. Few other things here are as polarizing.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 11, 2015, 10:41:11 PM
My thoughts. 2 doughs done side by side at the same time. 1on a porous stone material like cordierite and one on a very non- porous like a thick piece of tempered glass. But then you'd have to account for balancing the different conductivities, heat holding capacity, etc. I lean towards the stone making a dryer, crisper crust. But on the other hand baking steel is pretty non-porous and has gained quite a bit of popularity lately. Kind of on the fence leaning towards the stone, but it could be the Pavlov thing that we're forming ideas on what we've trained ourselves to think also. Just thinking out loud....... I will say my crusts are dryer and texturally crisper using the thicker cordierite stone in my BS vs the thinner, smoother stock stone, more even browning too

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: Bobino414 on May 13, 2015, 02:28:31 PM
Bob,

A couple thoughts on those observations;

- with respect to putting a metal pan on top of a stone, you create an air gap in the process which could have a significant effect on heat transfer. Unless you have a way to laminate the two, I'm not sure you can infer much from the test. If it were the case that baking on metal was a problem, why has steel plate been so successful? I still think it's largely a function of heat transfer not surface texture.

-there may be something to the idea that the texture on the stone provides a path for the steam to escape though I've seen plenty of bubbles form under the dough on a stone.

Craig,

I don't think air gap is a big issue here.  Although the metal sheet was not 100% in contact with the stone it still sat on the stone and the metal is highly conductive.  Also the metal sheet did bend upward slightly due to the oven heat toward the broiler element so it was approximately 2.5" from the broiler(about 1400*).   So to sum up I think two sources of heat on a highly conductive metal probably eliminates the air gap issue.

I have never baked on thick steel only so I cannot comment.

"I still think it's largely a function of heat transfer not surface texture."  I agree but it is only part of the story.

My thoughts. 2 doughs done side by side at the same time. 1on a porous stone material like cordierite and one on a very non- porous like a thick piece of tempered glass. But then you'd have to account for balancing the different conductivities, heat holding capacity, etc. I lean towards the stone making a dryer, crisper crust. But on the other hand baking steel is pretty non-porous and has gained quite a bit of popularity lately. Kind of on the fence leaning towards the stone, but it could be the Pavlov thing that we're forming ideas on what we've trained ourselves to think also. Just thinking out loud....... I will say my crusts are dryer and texturally crisper using the thicker cordierite stone in my BS vs the thinner, smoother stock stone, more even browning too

jon

John

Give yourself more credit as Pavlov is not in the room; you reported what you observed.

Bob

Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 13, 2015, 02:55:24 PM
John

Give yourself more credit as Pavlov is not in the room; you reported what you observed.

Bob

Ha, we're all just a bunch of dogs of different breeds anyway. I claim mutt, always been the fondest of mutts anyway :-D
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 13, 2015, 02:56:47 PM
I don't think air gap is a big issue here.  Although the metal sheet was not 100% in contact with the stone it still sat on the stone and the metal is highly conductive.  Also the metal sheet did bend upward slightly due to the oven heat toward the broiler element so it was approximately 2.5" from the broiler(about 1400*).   So to sum up I think two sources of heat on a highly conductive metal probably eliminates the air gap issue.

You may be right, but my gut feeling is that it is a bigger factor than you might think. The conductivity of the metal is largely a non-factor with respect to the heat passing through it from the stone. It doesn't matter how conductive the metal is, with respect to heat coming from the stone, it can only transfer it to the pizza as fast as the stone can transfer the heat to the metal, and it does have to pass through some amount of air what I think has to reduce the overall conductivity of the system. Maybe it's a trivial amount, I really don't know. It would be interesting to test but would probably require sacrificing a pizza stone.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tscarborough on May 13, 2015, 03:07:44 PM
It is not trivial.  Air is a great insulator.
Title: Re: MythBusters - Pizzamaking Edition
Post by: petef on May 13, 2015, 03:49:42 PM
My thoughts. 2 doughs done side by side at the same time. 1on a porous stone material like cordierite and one on a very non- porous like a thick piece of tempered glass.

I think you are on the right track but the 2 "stones" have to be identical material. One with a waterproof coating.

My suggestion is to get 2 unglazed quarry tiles from Home Depot. Then waterproof one tile with a high temperature paint such as Rustolium makes (800 deg F max). Then simultaneously bake 2 mini pizzas to see the result. Just don't eat eat them due to the toxicity of the paint. :)

---pete---



 
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 13, 2015, 04:15:11 PM
I think you are on the right track but the 2 "stones" have to be identical material. One with a waterproof coating.

My suggestion is to get 2 unglazed quarry tiles from Home Depot. Then waterproof one tile with a high temperature paint such as Rustolium makes (800 deg F max). Then simultaneously bake 2 mini pizzas to see the result. Just don't eat eat them due to the toxicity of the paint. :)

---pete---

Better yet, a cordierite stone (because it's so porous), tape it off and seal 1/2 of it. Cure it and slap a dough on it right in the middle and do an upskirt to see the results. Or 2 smaller doughs, observe and weigh
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 13, 2015, 04:20:40 PM
I think we are pretty much all in agreement that no water is absorbed by the stone. I believe the question at this point is: does the porosity or texture of a stone somehow improve the final product as compared to a  non-porous material with similar thermodynamic properties.

I really don't believe the Emile Henry micro-crazing story. Comparing a EH stone to an unglazed corderite stone might shed some light on things.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 13, 2015, 05:19:28 PM
In the approximately 72 hours since I put the bricks (or pavers as the case may be) outside after the test, they have reabsorbed from the atmosphere, 9.2g and 9.5g of the 40.0g and 41.1g water they released when I heated them.
Title: Re: MythBusters - Pizzamaking Edition
Post by: mitchjg on May 13, 2015, 05:26:00 PM
I think we are pretty much all in agreement that no water is absorbed by the stone. I believe the question at this point is: does the porosity or texture of a stone somehow improve the final product as compared to a  non-porous material with similar thermodynamic properties.

I really don't believe the Emile Henry micro-crazing story. Comparing a EH stone to an unglazed corderite stone might shed some light on things.

Maybe cover 1/2 a stone with a layer of carefully and beautifully laid out aluminum foil?  The materials will no longer be identical, but "whatever." 

Yes, the micro-crazing story is macro-crazy. 
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 13, 2015, 05:43:48 PM
I think that's worth a try. Cover half a pizza stone with thin aluminium foil and bake a pie with the edge right down the middle.

Any takers?
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 13, 2015, 07:03:36 PM
I was thinking of making a white mushroom pie later this week or weekend using some homemade cultured cream. Maybe I'll start a dough tonite. Forgot how much I like that cultured cream drizzled thru the top of the shreeded cheese and let it all goo together :drool: If I do I'll give it a try and make an extra dough for science :-D

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: MartyE on May 13, 2015, 10:31:32 PM
Maybe cover 1/2 a stone with a layer of carefully and beautifully laid out aluminum foil?

Tampa tested this a while back.
http://www.pizzamaking.com/forum/index.php?topic=10987.msg99391#msg99391 (http://www.pizzamaking.com/forum/index.php?topic=10987.msg99391#msg99391)
Title: Re: MythBusters - Pizzamaking Edition
Post by: Crispy Please on May 14, 2015, 07:29:14 AM
This topic has generated a startling amount of interest. I lack the requisite education as to the physics, but the testing part is easy. But not cheap.

Get an Emile Henry glazed stone.
Cut it in half.
Flip one half over.
Push the two halves together.
Bake a single dough, half over each side.
Measure.
Repeat.
Repeat..... :(

-Crispy
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 14, 2015, 08:17:39 AM
Tampa tested this a while back.
http://www.pizzamaking.com/forum/index.php?topic=10987.msg99391#msg99391 (http://www.pizzamaking.com/forum/index.php?topic=10987.msg99391#msg99391)

That would seem to explain Bob's observations.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 18, 2015, 09:40:03 PM
So went ahead and did the test using foil on 1side of the peel. Made this crust brushed with some herbed garlic butter, wonderful eating for a science project btw, lightly docked with the docking roller. Rolled out pretty evenly to 14"with pastry roller. Dough was 300 grams. I had Rosie try it first, looking, feeling and then taking a bite of each slice. We both agreed, no contest, foiled side lost. Both delicious, but for texture, crunch factor unfoiled was a significant winner

jon

Title: Re: MythBusters - Pizzamaking Edition
Post by: Bobino414 on May 18, 2015, 10:03:05 PM

Well John, I'm a believer.   :)
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 18, 2015, 10:37:37 PM
I have to agree with comments in Tampa's thread cited above that this test is fundamentally flawed due to the stark difference in emissivity between stone and shiny foil.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 18, 2015, 10:51:19 PM
I have to agree with comments in Tampa's thread cited above that this test is fundamentally flawed due to the stark difference in emissivity between stone and shiny foil.

Maybe coating 1/2 the stone with a high heat glazing coating like for pottery use? If one did this and only did it on one side of the stone the other side could still be used conventionally. The only thing is, you would lose the ability to flip the stone once in awhile. Just another idea......

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 19, 2015, 12:07:51 PM
IMO these results support the hypothesis that stones absorb moisture.  The stone absorbed 0.1 g while in the oven, that evaporated in 30 s.  You've been thinking of this as a problem of total stock, when instead you should be thinking as a flux (g H2O/cm2/s).  For example, if the stone is fluxing 0.1 g H2O/cm2/30s, that could be a substantial amount of water in some cases.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 19, 2015, 01:07:26 PM
IMO these results support the hypothesis that stones absorb moisture.  The stone absorbed 0.1 g while in the oven, that evaporated in 30 s.  You've been thinking of this as a problem of total stock, when instead you should be thinking as a flux (g H2O/cm2/s).  For example, if the stone is fluxing 0.1 g H2O/cm2/30s, that could be a substantial amount of water in some cases.

I don't think that conclusion follows. First of all, no liquid water is coming out of a pizza.   This was an intentionally extreme example. I dropped 5ml of room temp water in a spot about the size of a half dollar. The next set of experiments is far more relevant particularly when taken together with the first. When a pizza was baked on the stone, the weight of the stone went down 1.4g loosing 14X more moisture in the stone than the stone gained when 5ml water was placed directly on it. Next, when 5ml of water was placed on the stone and a pizza baked on top of the water, the stone gained the same 0.1g as when the the water alone was placed on the stone - ergo, it would seem that significant amount of moisture is not being absorbed by the stone from the pizza.
Title: MythBusters - Pizzamaking Edition
Post by: David Esq. on May 21, 2015, 04:11:28 AM
Craig, "it would seem" that there is another test to be conducted. Make 2 pounds of dough. Evenly divided it. Shape and place 1/2 on the cold stone and 1/2 on a solid non porous surface. Keep the dough side by side and wait. Then weigh the dough.

Maybe the results show the stoned dough weighs less in which case "it would seem" that the porousness of the stone impacted the dough.

But weigh the stone before and after to check.

Maybe the results show no difference in weight which would seem to mean water removal was not facilitated by the porousness. On the other hand we are not talking about a lot of water here. It would seem that the water on the surface is what we are talking about and, that the surface water may actually weigh too little to measure with a home scale.
Title: Re: MythBusters - Pizzamaking Edition
Post by: David Esq. on May 21, 2015, 04:12:33 AM
By the way, in the name of mad science, you are going to get an award here  for thoroughly investigating.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Crispy Please on May 21, 2015, 04:56:18 AM
Porosity aside, can someone explain how liquid water, which vaporizes at ~212F, can be absorbed by any unconfined mass that is heated to and kept at 500F-1000F?

-Crispy
Title: Re: MythBusters - Pizzamaking Edition
Post by: norma427 on May 21, 2015, 07:32:26 AM
Craig,

I really don't understand, but think when I bake on a stone that is well seasoned (in my deck oven) the pizza seem to bake better than when baking on parts of the stone that are not well seasoned. 

Norma
Title: Re: MythBusters - Pizzamaking Edition
Post by: David Esq. on May 21, 2015, 07:44:38 AM
Those may be assumptions that do not occur throughout the entirety of the bake. Immediately after launch the surface of the stone comes in contact with moisture and is covered by an insulating blanket of dough that continues to cool off that surface. The water absorbed, if any, might later be expelled. Again, we may only be talking about a percentage of water on the bottom surface of the dough, so the quantity need not be great. Moreover, water does not instantly vaporize at 212 else a pot of boiling water would last no longer than a moment.

So, between the slow conversion from water to steam and the potential temporary cooling of the stone surface when covered by the damp blanket (or moisture ladened dough) it seems possible to have moisture transferred to a porous stone that is initially quite hot.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 21, 2015, 02:37:14 PM
Craig, "it would seem" that there is another test to be conducted. Make 2 pounds of dough. Evenly divided it. Shape and place 1/2 on the cold stone and 1/2 on a solid non porous surface. Keep the dough side by side and wait. Then weigh the dough.

Maybe the results show the stoned dough weighs less in which case "it would seem" that the porousness of the stone impacted the dough.

But weigh the stone before and after to check.

Maybe the results show no difference in weight which would seem to mean water removal was not facilitated by the porousness. On the other hand we are not talking about a lot of water here. It would seem that the water on the surface is what we are talking about and, that the surface water may actually weigh too little to measure with a home scale.

We know from people using wood dough trays that enough moisture is absorbed by the wood that the bottom of the dough ball dries slightly. I would not be surprised if cold, porous stone had a similar effect, but not in 10 or even 20 minutes if trying to simulate a bake time. I also don't think you can compare results of tests below and above the boiling point of water.

If there is another test, it would seem that the proposal to cut an Emile Henry stone in half and remarry the two with one side upside down is the most likely candidate.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 21, 2015, 02:38:00 PM
Craig,

I really don't understand, but think when I bake on a stone that is well seasoned (in my deck oven) the pizza seem to bake better than when baking on parts of the stone that are not well seasoned. 

Norma

By seasoned, do you mean darker in color?
Title: Re: MythBusters - Pizzamaking Edition
Post by: norma427 on May 21, 2015, 05:48:24 PM
By seasoned, do you mean darker in color?

Craig,

Yes, I mean seasoned by darker in color and more worn.

Norma
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 21, 2015, 05:56:02 PM
Craig,

Yes, I mean seasoned by darker in color and more worn.

Norma

That would make sense in light of November's comments in Tampa's thread cited above. The darker surface is likely more emissive and therefore delivering more IR energy to the bottom of the pie than would a lighter colored surface.
Title: Re: MythBusters - Pizzamaking Edition
Post by: norma427 on May 21, 2015, 06:18:15 PM
That would make sense in light of November's comments in Tampa's thread cited above. The darker surface is likely more emissive and therefore delivering more IR energy to the bottom of the pie than would a lighter colored surface.

Craig,

I see now that makes sense in light of November's comments in Tampa's thread. 

I think my regular home corderite stone is also baking better since it is more seasoned since is has somewhat of a darker surface in some places.  It must be getting more emissive since I spilled so many things on it from making pizzas.

Norma
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 26, 2015, 06:40:55 PM
Another nail it the coffin for this myth: http://www.pizzamaking.com/forum/index.php?topic=37744.0
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 26, 2015, 10:17:12 PM
Porosity aside, can someone explain how liquid water, which vaporizes at ~212F, can be absorbed by any unconfined mass that is heated to and kept at 500F-1000F?

-Crispy

It doesn't absorb into the mass, it diffuses into the air within the pores, just like it diffuses into the hot air in the oven.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 26, 2015, 10:55:39 PM
It doesn't absorb into the mass, it diffuses into the air within the pores, just like it diffuses into the hot air in the oven.

From the start of this thread I've felt absorbed is maybe a poor choice of wording. Allowing the bottom to breathe would maybe be closer to the mark with a more porous surface vs a sealed surface. I agree, a stone that's 600-800 is not going to absorb anything but a more porous surface will breathe better and give a more consistantly browned bottom. A sealed one or rather less porous surface will make steam pockets raising small areas of the crust that won't brown as well, paler, and other areas that brown fine or maybe too much. I hope this makes sense. That's the way I think of it anyway, crust can stay in more surface contact with the stone without being steam lifted up in spots. Agree, disagree????

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 27, 2015, 12:44:52 PM
It doesn't absorb into the mass, it diffuses into the air within the pores, just like it diffuses into the hot air in the oven.

Obviously it's the pores (the space not the air) where the water could go. However, steam expands as it heats forcing water out of the stone. Of course there will be some amount of water (in the form of steam) in the pores, but do the math, the mass of water that could possibly be absorbed into the stone is less than trivial.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 27, 2015, 12:56:31 PM
From the start of this thread I've felt absorbed is maybe a poor choice of wording. Allowing the bottom to breathe would maybe be closer to the mark with a more porous surface vs a sealed surface. I agree, a stone that's 600-800 is not going to absorb anything but a more porous surface will breathe better and give a more consistantly browned bottom. A sealed one or rather less porous surface will make steam pockets raising small areas of the crust that won't brown as well, paler, and other areas that brown fine or maybe too much. I hope this makes sense. That's the way I think of it anyway, crust can stay in more surface contact with the stone without being steam lifted up in spots. Agree, disagree????

jon

The problem with that theory is that the amount of water (in the form of steam) needed to fill the pores is a tiny fraction of a gram. Once the pores are filled, it will act the same as a solid surface. Try to blow into the stone, it's not like blowing into a fabric. It doesn't breathe like you are thinking. Also, if the stone is hotter than the pizza bottom, the pressure in the pores in the stone will be higher than the pressure of the steam coming out of the pizza above the stone and thus it will not enter the stone.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 27, 2015, 01:25:11 PM
Just for S & G I just went out in the garage and slowly poured about 1/2 cup of water onto the cordierite stone on my BS, water never reached the sides, literally sucked it up like a sponge leaving the surface barely moist. Blowing into this surface anyway I think would be like fabric albiet very hard fabric. I was even suprised at how much liquid it aborbed, VERY porous. Now this is not screaming hot but would demonstrate the difference from a sealed stone vs a very porous one.

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: mitchjg on May 27, 2015, 01:38:20 PM
Just for S & G I just went out in the garage and slowly poured about 1/2 cup of water onto the cordierite stone on my BS, water never reached the sides, literally sucked it up like a sponge leaving the surface barely moist. Blowing into this surface anyway I think would be like fabric albiet very hard fabric. I was even suprised at how much liquid it aborbed, VERY porous. Now this is not screaming hot but would demonstrate the difference from a sealed stone vs a very porous one.

jon

Now try it screaming hot..............but I hope you do not mind a cracked stone........it is a sacrifice for the sake of science and knowledge. 
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 27, 2015, 01:50:13 PM
Now try it screaming hot..............but I hope you do not mind a cracked stone........it is a sacrifice for the sake of science and knowledge.

I'll wait till I need a new one :-D
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 27, 2015, 04:16:03 PM
Now try it screaming hot..............but I hope you do not mind a cracked stone........it is a sacrifice for the sake of science and knowledge.

Exactly. Pouring water on a cold stone is meaningless in terms of this discussion. Not just because it would turn to steam on a hot stone, but more importantly, no liquid water comes out of a pizza dough.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 27, 2015, 05:20:45 PM
Exactly. Pouring water on a cold stone is meaningless in terms of this discussion. Not just because it would turn to steam on a hot stone, but more importantly, no liquid water comes out of a pizza dough.

I agree with you. I only did it to see how porous the stone is and it's actually much more so than I thought. Also agree, regardless of the stone composition, an extremely hot stone will not absorb water, but I think there is something to be said for the stones porous nature to diffuse steam/vapor/gas vs a sealed stone. It may not be significant enough to call a night and day difference but it's enough to affect a difference in the finished bottom browning and texture of certain baked goods like breads and pizzas and such. Is it better or worse......I think is a personal preference on ones tastes and what you're looking for aesthetically

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: jkb on May 27, 2015, 08:36:12 PM
At the risk of having my physics degree revoked, I don't give a damn about this.  All that matters is that the pizza tastes good.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 27, 2015, 08:45:55 PM
 :-D ^^^ tru dat. Still fun, and makes us all think about how and what we do a little differently!

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 28, 2015, 09:07:04 AM
but it's enough to affect a difference in the finished bottom browning and texture of certain baked goods like breads and pizzas and such.

On what are you basing that conclusion? I haven't seen a test that demonstrates that. If anything John's test of parchment suggests just the opposite.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tampa on May 28, 2015, 05:15:45 PM
On what are you basing that conclusion? I haven't seen a test that demonstrates that. If anything John's test of parchment suggests just the opposite.
If I understand the result from John's parchment test, it is that the bottom of the pie appears relatively crispy.  Parchment, like aluminum foil, is presumed to be non-porous so the steam didn't have a chance to get absorbed by the stone (if such absorption does indeed occur).

From Wikipedia: Modern parchment paper is made by running sheets of paper pulp through a bath of sulfuric acid (a method similar to how tracing paper is made) or sometimes zinc chloride. This process partially dissolves or gelatinizes the paper.

I'm not so sure that parchment results support the foil hypothesis since many things are different between the two mediums (eg: metal/non-metal, emissivities, stickyness to the dough, conductivity, etc.).  Parchment browns at baking temperatures and foil doesn't.  Are the porosities of aluminum foil and gelatinized paper the same at say 600F with the steam as the fluid?  I dunno

I'm still wondering about this myth.  It seems a complicated boundry layer problem.  New ideas welcome.

Dave

Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 28, 2015, 05:18:31 PM
Someone needs to sacrifice their Emile Henry stone...
Title: Re: MythBusters - Pizzamaking Edition
Post by: Crispy Please on May 28, 2015, 05:32:47 PM
Someone needs to sacrifice their Emile Henry stone...

Thanks for referring to this Craig. Different materials will produce different results (leoparding, browning, crisping, etc.) for many reasons which have been more than amply covered in this thread. But seriously, stone, ceramic, glazed, vitrified, and or steel plate simply cannot absorb H2O when heated to 600 degrees because, if for no other reason, the water evaporates on contact.

May I have another slice now?

-Crispy
Title: Re: MythBusters - Pizzamaking Edition
Post by: Bobino414 on May 28, 2015, 07:50:04 PM

Until the Emile Henry stone shows up, maybe we can move on to the next myth? :)
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 28, 2015, 10:44:27 PM
On what are you basing that conclusion? I haven't seen a test that demonstrates that. If anything John's test of parchment suggests just the opposite.

No tests, just my experiences over time and baking on any number of stones and ovens. Mine is not near as extensive as many here but just looking at the plethora of stones, surfaces, ovens, temps, thickness factors.....all for each persons desired results per their needs and desired results. Can a hot stone aborb moisture, probably not. But I think it's obvious that many factors affect the end result in bottoms of crusts and near the top would be porosity and it's nature to diffuse or lack of porosity. I can tell the difference even from my Fibrament vs the cordierite. They are close but their is a difference. And lastly as I mentioned before, all about preference and where/how each stone is used. Is there a test to prove one over the other......I think it's the old Miller commercial......"Tastes Great.....Less Filling" :-D

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tannerwooden on May 29, 2015, 12:15:28 AM
Thanks Craig for bringing this up. I've always accepted the myth without thinking. I will eagerly await the next episode of Pizza Myth busters. In fact, I would love to see it get its own tab on the forum. I think there's a TON of fodder for future episodes (Blind taste test: Are San Marzanos really the best?, How helpful is Autolyzing?)

I'm wondering though, what if you MADE the stone porous enough for steam to escape? What if you drilled holes in it? Would the steam travel down? We know from  bubbles that it's down there. You would certainly lose heat retaining mass, but would there be a compensating benefit? Would there be a sweet spot? 1/2" steel would be a  great one to try this out on, as there is already SO much mass to begin with.

On testing the sourdough myth: Does anyone know if you can see the difference between different strains of yeast with a reasonably priced microscope? This would make some aspects of testing the myth easier.

I read an article in Popular Science a few years ago. Someone in Germany had the idea of genetically modifying plaque forming bacteria so it generates alcohol (miniscule amounts) instead of plaque. They did it and decided to test it on themselves (beginning of a zombie movie). It didn't work. The modified strain was immediately killed by stronger bacteria in the guy's mouth.

He proceeded to get hundreds of samples of saliva. He used the samples to have petri dish cage matches (Two Bugs Enter. One Bug Leaves!").

Long story short, the author of the article claimed the guy hasn't brushed his teeth or gotten a cavity in months. Could you do the same sort of experiment with starters?
Title: MythBusters - Pizzamaking Edition
Post by: David Esq. on May 30, 2015, 06:36:19 AM
Everybody says water becomes steam on contact with a 600 degree surface. But that is absolutely not what happens when the dough hits the stone.

First, as Craig points out, water does not come out of the dough in a liquid state.

Therefore, a cold dough hits a hot surface. And the temperatures begin to equalize.  While that process begins, the stone cools and the dough warms.

Eventually water leaves the dough at the top, for certain, in vapor form.

What is the temperature of the stone surface throughout the bake? 

At what temperature does water drawn out from dough "instantly" turn to steam on contact? What happens to that steam when it is under 1 PDO (pizza dough pressure)?  Does it condense into water and does water under 1PDO turn to stream at 212 or a higher temp?
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 30, 2015, 11:18:13 AM
The problem with that theory is that the amount of water (in the form of steam) needed to fill the pores is a tiny fraction of a gram. Once the pores are filled, it will act the same as a solid surface. Try to blow into the stone, it's not like blowing into a fabric. It doesn't breathe like you are thinking. Also, if the stone is hotter than the pizza bottom, the pressure in the pores in the stone will be higher than the pressure of the steam coming out of the pizza above the stone and thus it will not enter the stone.

the pores don't "fill", they provide pathways across which water vapor can move.  Just like soil, concrete, wood, etc., the stone has a conductivity that could be measured.  your data show this.  A porous stone is going to permit way more water loss than a slab of steel.
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 30, 2015, 11:19:59 AM
Just for S & G I just went out in the garage and slowly poured about 1/2 cup of water onto the cordierite stone on my BS, water never reached the sides, literally sucked it up like a sponge leaving the surface barely moist. Blowing into this surface anyway I think would be like fabric albiet very hard fabric. I was even suprised at how much liquid it aborbed, VERY porous. Now this is not screaming hot but would demonstrate the difference from a sealed stone vs a very porous one.

jon

exactly  :chef:
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tscarborough on May 30, 2015, 12:13:42 PM
At 600 degrees the absorption rate of corderite or (almost anything) is effectively and absolutely 0.0.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 30, 2015, 03:36:52 PM
the pores don't "fill", they provide pathways across which water vapor can move.  Just like soil, concrete, wood, etc., the stone has a conductivity that could be measured.  your data show this.  A porous stone is going to permit way more water loss than a slab of steel.

It doesn't work like that. Whatever minuscule amount of moisture that gets into the pores will expand as it heats preventing additional moisture from entering.

The water is coming out of the pizza one way or the other. A slab of steel isn't going to hold the water in any more than a stone is going to suck it out.
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 30, 2015, 03:42:18 PM
At 600 degrees the absorption rate of corderite or (almost anything) is effectively and absolutely 0.0.

The water doesn't absorb into the corderite, it evaporates into the hot, dry air in the pores.  It's the same exact process that happens on the top of the pizza.  If you think the pores are too small to transport significant amounts of water, do some reading on plant stomata.
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 30, 2015, 03:44:48 PM
It doesn't work like that. Whatever minuscule amount of moisture that gets into the pores will expand as it heats preventing additional moisture from entering

Uh... Ok, whatever you say dood.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 30, 2015, 03:55:33 PM
You don't know what you're talking about dude.

You keep telling yourself that if it makes you feel better.

If the stone is fully saturated with heat, pore pressure is going to be lowest at the surface under the dough where the stone is the coolest and there is nothing above to contain the expanding gas. Any water that enters the stone will begin to heat and expand. The only direction it will go is back up because it would require higher pressure than can be generated in order to move in any other direction.

This has nothing in common with plant stomata unless you have found some plant living on Venus.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 30, 2015, 04:03:23 PM
Uh... Ok, whatever you say dood.

Thank you. Glad you came to your senses.
Title: Re: MythBusters - Pizzamaking Edition
Post by: CDNpielover on May 30, 2015, 08:22:31 PM
This has nothing in common with plant stomata unless you have found some plant living on Venus.

yes it does - my point is that large amounts of water can evaporate through tiny pores.
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 30, 2015, 08:43:58 PM
yes it does - my point is that large amounts of water can evaporate through tiny pores.

We are not talking about liquid water or water vapor. We are talking about steam - and most particularly, steam of increasing temperature which will either increase in volume or pressure depending on whether it is contained or not. The top of the stone is open and cooler than the middle (the pie cools it after launch). The farther you go towards the middle, the hotter it gets and the more contained it gets. This is why the initial water (steam) will move away from the center right back to the top of the stone where it came from where it's cooler and the pressure is lower as opposed to the center where it's hotter and the pressure is higher - pushing any other water (steam) coming out of the pizza away from the stone just as a steel plate would. That amount of water that ever enters a pore in the stone is trivial at best. 
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 30, 2015, 09:29:09 PM
How would this work as a test? I have an extra 3/4" cordierite stone and would be willing to sacrifice part of it as follows. I'll get some pottery glazing compound that can tollerate high heat and glaze 1/2 of it, basically clear coat it thus retaining its original color. Now this will not prove or disprove any aborptive abilities of the stone but will show it's ability to diffuse moisture away from the crust. If there's no change from one side of the crust to the other or if there is a significant change it should be apparent. Now I'll qualify my thinking as I did earlier, I don't think a hot porous stone can aborb any water. Now it can absorb oils as most anyones stone will show by it's stains. But I do think a porous stone or surface can and does affect the crust by it's ability to allow some amount of diffusion letting the crust release moisture in it's vaporous/gasseous state in more directions than up, letting it go down and more laterally. So back to my question, will a clear coat glazing 1/2 the stone be an acceptable test?

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 30, 2015, 09:34:41 PM
Plenty of steam comes out of the bottom of the pie no matter what surface you bake it on. You couldn't stop steam from coming out the bottom if you wanted to.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 30, 2015, 09:44:52 PM
But would that be a test worthy method. I think the more porous side allows more surface area of the dough to stay in contact with the stone thus more even browning vs the non-porous side with be floated more and more inconsistant browning. Not arguing just looking for your thoughts, might be an interesting test. Absorption thingy aside.

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: TXCraig1 on May 30, 2015, 10:52:29 PM
It sounds reasonable. I'm not sure it's worth spending money on though.
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 30, 2015, 11:14:48 PM
The only money would be the few bucks for the glazing compound and I'm thinking I could cure it in the BS, so the added cost of the gas used. I'll look into it in the next couple weeks. As far as which is better or worse IF there is a noted difference, again is a matter of taste/preference.

jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tampa on May 31, 2015, 12:20:53 AM
The only money would be the few bucks for the glazing compound and I'm thinking I could cure it in the BS, so the added cost of the gas used. I'll look into it in the next couple weeks. As far as which is better or worse IF there is a noted difference, again is a matter of taste/preference.
jon

Jon,

Thanks for offering to do the test.  I love the idea.  CDN and Craig both seem supportive.

Using a flat black glaze on 1/2 of the stone should take emissivity comparable between the two surfaces (a lot better than aluminum foil) and leave the untreated side porous.

To help defray expenses and your kind effort, I'll offer $20 if the results are substantially identical between the two bake surfaces.  (I'm still betting that the reason the foil side is blonde has to do with porosity.)

Dave
Title: Re: MythBusters - Pizzamaking Edition
Post by: Jackitup on May 31, 2015, 04:18:41 AM
Dave, thank you for your offer but I think the cost will be very small. The extra stone I have sits atop on the BS and acts as a heat sink, so really putting nothing out other than the glazinng compound and a little gas. All good, I'm as curious as anyone to see how it plays out!! Good stuff for all of us :P


jon
Title: Re: MythBusters - Pizzamaking Edition
Post by: Tampa on May 31, 2015, 12:35:09 PM
Good stuff for all of us :P
jon
Good stuff indeed!

I keep thinking about how to create a perfectly definitive test and can't offer much improvement.  For those that have seen MythBusters, there are always viewers critical of the methods used to debunk myths.  If you have suggestions/improvements, please share before the glaze is applied.

For me, the emissivity difference between aluminum foil and glazed tile is something like 5% and near 90%.  A used and charred cordierite pizza stone is near 90% - so we are good right?  IMO, probably good enough.  I might help if the stone was soiled again after the glaze firing to increase the emissivity from 70-something to 90%.  (Assuming firing will likely clean the stone like new).  That's my take, but improvements welcome.  Otherwise, as long as the glaze side is non-porous and similarly smooth, I think we have a very good test.

Perhaps we refer to the fans of steam as Steamers, and the foil emissivity fans as Foiled Agains?  Foiled Agains should enjoy knowing that the emissivity of paper up to 700F is comparable to stone, at 93% - helping support Craig's parchment paper observation.  :-\ (Here is the emissivity reference: http://www.omega.com/literature/transactions/volume1/emissivityb.html).

Dave