Recreating Pepe's over a 10 year period

[scott123]

John, there's absolutely nothing in a kiln shelf that isn't inert/non-toxic. It's a ceramic- just like a dish or a mug. The shelf he's selling contains exactly the same components as the shelf you're baking with, just in varying quantities. He's telling you that they aren't food safe, not because they aren't food safe, but because because they aren't specifically made to be used with food, and, since he doesn't know if they're food safe, he's covering his legal butt.

Including the baking community, literally thousands of people using kiln shelves for baking. There's no lead in them, no mercury, no heavy metals, nothing toxic.

Write him back and ask him why they aren't food safe.  A thousand bucks says that he will have no reason other than "they're not made for eating."

Edit: Why would someone use a kiln shelf made from toxic materials to fire dishes and cups that people are going to eat off of?

[CDNpielover]

scott, i don't know what you mean by steam going up and not into a stone - but evaporation from the bottom of the dough is driven by a vapor pressure deficit.  if there is a porous stone with hot, dry air in the pores, you will have water moving down a water potenital gradient and thus from the dough into that air.  it has little to do with density, or gravity.  

I understand you are a massive proponent of the steel plate, but i'm not convinced by your argument that stones do not permit more water loss than a steel plate would.  IMO, the steel plate is reducing your evaporative surface area by about 1/2 (neglecting the "sides" of the dough).

[buceriasdon]

CDN, I'm not quite sure where or how the myth of water absorption at baking temps begain but that's what it is......a myth. Heat a stone or a cast iron skillet to 600 degrees, sprinkle some water drops on the surface, the water on both will turn to vapor in an instant. Vapor equals steam which is a gas and cannot be seen. It's impossible at those temps for absorption to be a factor. I know how people say " But my pizza stone absorbs water when I pour water over it Don!"  True, but that is at room temp.
Don

[John in Florida]

Scott, no argument, just passing along info.

[CDNpielover]

CDN, I'm not quite sure where or how the myth of water absorption at baking temps begain but that's what it is......a myth. Heat a stone or a cast iron skillet to 600 degrees, sprinkle some water drops on the surface, the water on both will turn to vapor in an instant. Vapor equals steam which is a gas and cannot be seen. It's impossible at those temps for absorption to be a factor. I know how people say " But my pizza stone absorbs water when I pour water over it Don!"  True, but that is at room temp.
Don

I see what you're saying, but I am not convinced.  Water vapor moves in response to vapor pressure/water potential, and will move down a water potential gradient in any directon.  When wet dough is on a hot stone, water can evaporate and flow through the air-filled voids, but this is not possible on a steel plate.  it seems to me that a steel plate reduces the evaporative surface area of the dough   

[buceriasdon]

 CDN, The Leidenfrost Effect clearly states that water particles can not penetrate a super hot surface they are next to but will be held in suspension by water vapor until totally vaporized, plus the Leindenfrost Effect occurs at temperatures well below what we are talking about here. How can water molecules penetrate a surface when they are being turned into water vapor, perhaps not at a constant rate because of temp variations of the surface and dough varibles, but converted none the less? Thanks for the exchange.
Don

[CDNpielover]

I am not familiar with that, I will have to take a look and think about it.     again, my initial impression is that the LE seems to apply to non-porous surfaces. 

[scott123]

Scott, no argument, just passing along info.

John, I hope I didn't come off as shooting the messenger. Obviously, my anger is directed towards this individual, not you.

[John in Florida]

Oh no, no worries Scott, likewise I have encountered this sort of food/no food thing in the past and was just data gathering from this outfit. Many years ago I did a lot of "warm" glass work in kilns, around 1200 degrees, and thought about using the kilns for pizza making. Never did because they were top loading, not so good, and I was in fact using chemicals that would not do well in food.

Through all this you have made me think of trying the broiler in my oven in lieu of the bake mode. This oven says you can broil all day at 550 with the door closed. So what I'm thinking is let it soak with the door closed heating the stone, then shovel in the pie where the stone works on the bottom and the broil element does the top. Can't hurt to try...

[scott123]

scott, i don't know what you mean by steam going up and not into a stone - but evaporation from the bottom of the dough is driven by a vapor pressure deficit.  if there is a porous stone with hot, dry air in the pores, you will have water moving down a water potenital gradient and thus from the dough into that air.  it has little to do with density, or gravity.  

I understand you are a massive proponent of the steel plate, but i'm not convinced by your argument that stones do not permit more water loss than a steel plate would.  IMO, the steel plate is reducing your evaporative surface area by about 1/2 (neglecting the "sides" of the dough).

Alright, here's what I know:

1. Non porous stones produce identical results to porous ones.

2. With the exception of Fibrament, almost all stones that we might consider porous really aren't that porous at all.

My thoughts on LE are only my best way of justifying #1. I'll concede that LE may or may not be in play here.  I don't know.  I do know and have witnessed non porous stones producing just as dry and crispy undercrusts as porous ones.

I guess, if a home baker was striving for an unparallelled level of crispness while maintaining a maximum amount of residual water in the crumb, then, perhaps, Fibrament, at higher temps, might be the stone for them.  But this is crispier than just about any pizzeria, as most pizzeria stones are non porous.

[scott123]

Through all this you have made me think of trying the broiler in my oven in lieu of the bake mode. This oven says you can broil all day at 550 with the door closed. So what I'm thinking is let it soak with the door closed heating the stone, then shovel in the pie where the stone works on the bottom and the broil element does the top. Can't hurt to try...

John, I'm not a big fan of broiler pre-heats or bake pre-heats with last minute broiler 'bumps'.  Because your broiler is so close to the thermostat, it's driving up the temp of the thermostat quickly and shutting off. It's not a soaking heat from a bake pre-heat, but more of an intermittent blast that might drive up the top of the stone a bit, but doesn't really penetrate.

Fast baked pizza is not about the temp that's on the top of the stone, but the temp of the core.  A 1/2" stone that's 600 degrees throughout will bake a pizza far faster than the same stone with 1/16" of it at 800 while the rest of it is 500.

That being said, even if you could get the heat to penetrate, the broiler answers to the same traffic warden thermostat that the baking element answers to.  Peak oven temp is peak oven temp.  That thermostat is going to cut out at, in your case, 600ish, regardless of whether the broiler is on or the bake element is on.  All you're doing with a broiler pre-heat is extending your pre-heat time because of the relatively ineffectiveness of IR radiation compared to convection.

Now, I don't think the numbers are high, but there are some oven owners with broilers that don't shut off.  I don't comprehend how a broiler that doesn't shut off could possibly be safe, but, since I don't hear about houses burning down from this sort of thing, I can only assume that, for these handful of people, these perpetual broilers don't carry any risk.

These kinds of ovens are definitely not the norm, though, and I think it's more of an older oven phenomenon than a newer one. I don't think you're one of these lucky(?) owners, but you might as well crank your oven to the highest broiler setting and see if it stays on.  If it does, then there's no need for a new stone.

[buceriasdon]

 OK, Let me explain it another way. Kinetic Molecular Theory states that when a gas or liquid is heated the molecules and atoms move at an accelerated rate and that they move away from the source of the heat not towards. As the excited particles move away or repelled they displace slower moving molecules towards the heat source as they have more stored energy, and the process then repeats itself. In other words convection occurs not absorption.
Don

[CDNpielover]

thanks for your thoughts guys.  i'm still not convinced porous stones don't remove more water than non-porous, but Scott's remark about most stones are not actually porous does help refute the water loss myth.   

[buceriasdon]

Scott mentions Fibra Ment :Read point number 14 on the Breadtopia site. Imagine that, someone actually agrees with me.

http://www.breadtopia.com/baking-pizza-stones/
or maybe they are all wet also
Don

thanks for your thoughts guys.  i'm still not convinced porous stones don't remove more water than non-porous, but Scott's remark about most stones are not actually porous does help refute the water loss myth.  

[CDNpielover]

^^thanks for this link.  that page says "It’s hard to imagine a stone heated up to 600°F can absorb moisture. Moisture evaporates very quickly at those temperatures."

Essentially, they are arguing that a hot stone cannot remove water because the water is vapor, however they are neglecting the fact that transport of water vapor can occur through the gas in the pores of the stone.  These pores can actually enhance the evaporation that they refer to in their quote. 

[buceriasdon]

How can H2O be turned into vapor and be absorbed in the pores of the stone when I have shown that can't happen?¿ The temperatures that any porus surface would absorb water in dough at would be incapable of baking a pizza. Read:  http://en.wikipedia.org/wiki/Leidenfrost_effect
This happens way below the temps we are discussing. I don't see any absorption there. Read :   http://www.ehow.com/facts_7200681_heat-one-place-another-convection_.html  
Again how is absorption possible when clearly molecules move away from the hot surface?
Don

^^thanks for this link.  that page says "It’s hard to imagine a stone heated up to 600°F can absorb moisture. Moisture evaporates very quickly at those temperatures."

Essentially, they are arguing that a hot stone cannot remove water because the water is vapor, however they are neglecting the fact that transport of water vapor can occur through the gas in the pores of the stone.  These pores can actually enhance the evaporation that they refer to in their quote.  

[CDNpielover]

but i'm not saying the water is "absorbed" into the stone - i'm saying it may evaporate into the air contained within the stone - and perhaps be able to diffuse that way through the pore channels of the stone.    

I am not sure that the LE really applies to a pizza cooking in an over.  first, the LE effect applies to a single water droplet on a non-porous surface, which isn't the case at all for a pizza dough (which is again a porous structure holding water).  but if we put a pool of water on a porous stone, even then I think the LE describes a different phenomenon - or at least, a different case of the same phenomenon - as I think water vapor would also be able to diffuse into the air contained within the stone.  water likes to move into hot, dry air!  

anyhow - my intention here isn't to argue, i just have a curious mind.  I'm not saying i have proof that water moves through a porous stone, just that I'm not totally convinced that it doesn't.   

[polishpizza]

This is an awesome post and I just wanted to thank all the contributed.  Right now I have little to give back but I'll try to make it up.  I donated money to the site for starters.