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I asked some time ago questions regarding a pizza oven I planned to buy and bought eventually.

As the oven is pretty small it's difficult to maneuver inside it pizzas that are more than bite-sized. My idea was to use some sturdy stainless steel plate that should withstand the 500 degree Celsius inside the oven, which I will manually rotate with the pizza on it.

I bought some custom-made 316 stainless steel plate, but it suffers from the issue I suspected might happen. The heat transfer from it to the pizza doesn't occur very effectively even though it has a much higher thermal conductivity than cordierite, possibly because its emissivity is significantly lower (at least when polished and clean) and thus any area in the dough which doesn't contact the plate perfectly gets very little crusting.

Another thing not helping is that my dough is quite sticky and requires plenty of flour in order to leave the peel, so that also adds a layer of barrier which probably reduces crusting. I tried with (coarse) semolina too and the results were worse.

So I want to improve the emissivity of the plate. My question is whether seasoning the plate with oil could achieve that, and whether seasoning in such high temperatures is problematic?

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    There's another possibility: how heavy is that round steel plate? You need some mass to make something work as a baking steel.
    – FuzzyChef
    Apr 13, 2022 at 0:12
  • Also, did you confirm that the pizza oven worked well with the original corderite stone before you replaced it?
    – FuzzyChef
    Apr 13, 2022 at 0:13
  • @FuzzyChef It's quite thin at 2mm thickness as every additional millimeter made it excessively more expensive to fabricate, and it weighs a little less than 1.5kg. Density-wise it's about as a 8mm thick stone, which isn't much but should be enough to get at least one pizza right after warming up. Regarding the oven, I just burned the pizzas every time before getting a rotatable base so I'm not sure how well was the underside crusting, but it logically was better.
    – TLSO
    Apr 13, 2022 at 2:41
  • see answer below, then. that's your actual problem.
    – FuzzyChef
    Apr 13, 2022 at 21:33

3 Answers 3

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I doubt if seasoning will have a major effect on the emissivity of the stainless steel, and you may actually encounter more problems with the polymerized oil flaking off at such a high temperature you are using, which is much greater than a regular domestic oven.

You didn't explicitly state if the cordierite is an integral part of your pizza oven, assuming it is, you have to consider two variables apart from the temperature inside the oven, the heat transfer between the cordierite and the stainless steel, and that between the stainless steel and the pizza itself.

To improve the former at such high temperatures, in engineering environments normally a layer of thermal compound would be used. However, at such temperatures regular thermal paste compounds would break down. In theory, this approach would improve matters somewhat, but probably not to the degree you are looking for. I suspect getting a certified food safe product would be challenging, and also finding something non-destructive that works well with cordierite and steel. There are epoxies that will cope with these types of environments (e.g. T-99), but this would be a permanent process as the steel would be effectively glued to the base of the pizza oven in perpetuity, something you probably don't want for practical reasons.

As to the latter problem, the addition of sugar and oil to your pizza dough is probably the most viable suggestion.

In the first instance, I would try heating the stainless steel for a much longer period before use. You may be able to utilise the environmental temperature to your advantage here, but without knowing exactly how your oven is heated,YMMV.

Practically though, if you just want to improve the emissivity I would abandon the steel and use cast iron. Steel has a very low emissivity rating of 0.07. If you want to increase that factor, using a cast iron dish or skillet would raise that almost by a factor of 10 to 0.64.

https://www.seriouseats.com/the-truth-about-cast-iron

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    It seems from reading around that the burned seasoning is already not that healthy in the first place, so in an oven that burns at 500 Celsius it might be worse. But it does seem the burned matter has a much higher emissivity. Regarding iron, I read it reaches this emissivity after oxidizing, polished clean it is at first similar to the stainless steel. So the issue is that iron would probably rust terribly in these temperatures, but as oxidized stainless steel is said to rate at emissivity similar to the cast iron – perhaps the oxidation it also goes through would improve this in time.
    – TLSO
    Apr 11, 2022 at 0:56
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What temperature is your oven? I get browning with plain steel cookie sheet at 500 F. Usually I use the gas grill which is a little hotter but I don't remember measurement. I assume you do not set your oven at 930 F- 500 C.I have baked apples at temps like 700 F in industrial furnaces , they cook pretty fast .

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  • It's a pizza gas oven that has burners only above the floor, so the heat from below the pizza needs to build up and hopefully be released efficiently enough onto the lower crust. The oven can reach about 500 Celsius.
    – TLSO
    Apr 11, 2022 at 0:52
  • I suggest an infra red temperature sensor to check temperature. I worked professionally with temperature for 40 years, there are always unexpected results When heat-treating some critical components , a thermocouple is welded directly to the part. You want a solid part temperature , not a gas temperature. Apr 11, 2022 at 23:59
  • The measurement was with an infrared sensor. But of course when measuring the stainless steel plate it showed with the IR sensor much lower temperatures, as it doesn't radiate as much as it conducts.
    – TLSO
    Apr 12, 2022 at 10:40
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Seasoning will make no difference at all in browning. Commercially-made Baking Steels are coated with a very high-temperature seasoning to prevent rust, and not because it improves emissivity. If anything, seasoning would decrease emissivity and conductivity to the pizza, but probably by too small of an increment to measure.

No, there are two possible likely reasons for browning being poor on your new steel plate:

  1. You're not letting it preheat enough. My Ooni needs to preheat for 20-35minutes for the baking surface to reach 425C. If I put a pizza in before it reaches this temperature, it's pale on the bottom when done on the top.
  2. The steel plate you're using doesn't mass enough, and it's probably also attached to something that lets it conduct away heat.

Pizza ovens are floored with something heavy, whether corderite, tile, refractory concrete, or heavy steel plate. This is because the mass of the flooring needs to absorb and radiate heat back, and thermal capacity is determined by mass more than any other factor. This is why commercial Baking Steels weigh between 7kg and 18kg; you need that mass to absorb and hold heat.

So if your custom round steel is light, it's not going to retain heat, especially after you put wet pizza dough on it. You might also have it bolted to something, like a turning shaft, that connects to the outside of the oven or even sticks out of the oven entirely. This connected piece of metal would then act as a radiator fin, cooling the steel.

The fix for this is to use a heavier/thicker piece of steel. Secondarily, to use a high-temperature insulator between it any any other conductive metals it directly attaches to.

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  • I'm not sure what exactly is commercial baking steel coated with, but per the internet the emissivity coefficient of polished carbon steel is 0.07 while something like carbon for example or well rusted steel is about 0.8. The conductivity would be less, but as I said it might be that for effectively crusting the pizza it needs to be mediated as radiation. Regarding my oven situation, the steel plate is actually not connected to anything and is just sitting on the cordierite that came with the oven.
    – TLSO
    Apr 14, 2022 at 7:34
  • Then how are you rotating it?
    – FuzzyChef
    Apr 14, 2022 at 18:03
  • I'm just grabbing it with a plier, pulling then pushing from each side.
    – TLSO
    Apr 14, 2022 at 19:16
  • Oh! So this is just on top of the built-in corderite? In that case, the problem is that not enough heat is getting through to it, given the bottom heat of the oven. I'd suggest giving up on the steel disk and getting a turning peel instead.
    – FuzzyChef
    Apr 14, 2022 at 23:39
  • Well, as heat transfer to and from stainless steel needs close contact, the cordierite probably doesn't transfer heat much into the steel. But I still think the issue isn't that there isn't enough heat stored in the plate, but that the mode of heat transfer doesn't work well enough for pizza. But as it's starting to oxidize, I'll need to see whether that would improve something eventually.
    – TLSO
    Apr 15, 2022 at 0:21

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