Types of cordierite

[ivowiblo]

Hi!
I recently changed my cordierite stone for a new one the same thickness but redish in color.
The old one was broken in two and also has a rough surface due the many many pizzas I made (probably the metal peel has something to do with ti).

I'm finding that the new stone burns a little bit more than the old one, but in a more unven way. With a high temperature the old one will produce many charred spots, some burnt. the new one will maybe produce the same spots as if it was colder but those spots will burn. It's like the space between the spots gets elevated maybe a 1-2 mm.

Also, when I do a cheeseless pizza (like a marinara) it the dough blows as there is no heavy topping to push it down. It's not that the dough inflates like a pita. the pizza floor goes up and the pizza ends up cooked but completely pale. if I put cheese but left a spot without it, that spot will also blow.

Finally, I found that the temperature readings across the stone is much uneven that on the old one.

I'm using a modified electric countertop oven but it should behave more or less like an ooni.

So, besides it looks like it is the stone, I'd like to understand what could be going on with this particular one so the new one ends up being more like the first one (besides "not buying a red one")

Do you guys have any idea?

Thanks!

[TXCraig1]

Can you post a link to the new stone?

[ivowiblo]

hanks for your answer

I don't even know where I bought it. I'm from Argentina and I don't believe there's any technical information on them. But I have a picture of them

[Timpanogos Slim]

From wikipedia:

Cordierite (mineralogy) or iolite (gemology) is a magnesium iron aluminium cyclosilicate. Iron is almost always present and a solid solution exists between Mg-rich cordierite and Fe-rich sekaninaite with a series formula: (Mg,Fe)2Al3(Si5AlO18) to (Fe,Mg)2Al3(Si5AlO18).[3] A high-temperature polymorph exists, indialite, which is isostructural with beryl and has a random distribution of Al in the (Si,Al)6O18 rings.[4]

Cordierite baking stones would seem to be fired ceramics that are composed largely or entirely of cordierite and probably minerals found near it. They would tend to vary by the grain size and density i think? Modern catalytic converters are made from synthetic cordierites with an aligned crystal structure so that they have nearly no thermal expansion.

The reddish color might be sekaninaite?

I can say that the cordierite stone my parents bought in the 80's which is still in use today has a color near as dark as yours and visually appears to be coarser grained than the stones i have bought from Unicook or which came with pizza ovens i own, which are pretty pale yellow.

Cordierite is used for most baking stones because it works well enough and is relatively cheap.

The more expensive pizza stone materials - Fibrament-D from AWMCO and possibly other brands of cementitious baking stones outside of the USA have lower thermal conductivity resulting in a more gradual transfer of heat, and "Biscotti" ceramic stones from Italy have a yet lower thermal conductivity and seem to be preferred for very high temperatures.

I know a ceramics nerd but he isn't online right now. I'll ask what he may know about cordierite ceramics.

[ivowiblo]

Wow, thank you so much.

it makes sense that the redish tone is something related to iron and I would imagine that iron transfer heat more quickly, so maybe that's it.

I'll keep investigating following this lead. Thank you so much

[Timpanogos Slim]

I did get in touch with my friend - he mostly knows about cordierites that form in a ceramic body *during high temperature firing, and that they are desirable because they reduce susceptibility to thermal shock.

[ivowiblo]

Thanks