MythBusters - Pizzamaking Edition

[CDNpielover]

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.

[TXCraig1]

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.

[TXCraig1]

Uh... Ok, whatever you say dood.

Thank you. Glad you came to your senses.

[CDNpielover]

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.

[TXCraig1]

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. 

[Jackitup]

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

[TXCraig1]

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.

[Jackitup]

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

[TXCraig1]

It sounds reasonable. I'm not sure it's worth spending money on though.

[Jackitup]

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

[Tampa]

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

[Jackitup]

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


jon

[Tampa]

Good stuff for all of us
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