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Even heat challenge -- copper diffuser plate?


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Even heat challenge -- copper diffuser plate?

athanasius | Dec 19, 2010 09:46 PM

I've been reading many of the recent threads about experiments comparing cookware of various materials with great interest. (As some may remember, I posted my own initial results a couple months back with an IR thermometer:

With all of these tests by so many people, we have empirical evidence that slow response materials like cast iron and stainless steel have hot spots that can produce significantly uneven heating and scorching under many common cooking conditions. But obviously people who love certain kinds of materials (particularly cast iron), still like them and want to use them for all sorts of reasons. I too would like to have a way to use my cast iron pans more often.

Here's what I'm wondering: what about those copper stovetop diffuser plates? Most I could find are 1/8" thick copper plates -- at least as thick as the 2.5-3.0 mm copper we see recommended for good copper cookware. Thus, they should be able to distribute heat across the surface of the plate as well as copper cookware.

Here are a couple links:

Obviously, one could get a piece of copper plate cut to spec from a sheet metal source as well.

Does anyone have experience using a copper plate to mediate between an uneven burner and an uneven pan? How does it work for you?

Just in theory -- assuming we have a pan with a flat bottom that mostly makes contact with the copper surface of a diffuser plate, could we transform a cast iron (or stainless) pan into a relatively even heating surface? Obviously, we'll lose some responsiveness, since the heat has to diffuse through a lot of metal -- but cast iron isn't good at responsiveness anyway, so would this be any worse? And we'll lose some efficiency -- extra heat is needed to raise the temperature of the copper, and it will radiate off exposed surface around the pan. But stovetop cooking energy use is usually pretty insignificant within household energy use (and it's already pretty bad in terms of heat energy efficiency).

We would effectively choose to even out the heat source before it reaches the pan, rather than even out the response of the pan. I know a number of people have suggested ways of making a more even heat source -- is this a reasonable one?

Even for fairly large copper plates, they cost less than $100 each. Even the smallest cheapest decent quality copper pan costs more than that. So, could a couple of these diffuser plates be a reasonable affordable alternative for someone who wants even heat but prefers to use cast iron or some other material for whatever reason? Obviously, this wouldn't be effective for pans without flat bottoms or for the occasional application that requires the sides of a pan to be as evenly heated as the bottom (where aluminum or copper pans are the only reasonable choices).

If these diffusers don't work well, why not? And if they do, why don't they come up as a good solution to some of the issues voiced in recent threads?

(Edit -- also, if these work, for those on a budget, an aluminum plate should be much cheaper, lighter, and also quite responsive. I don't see aluminum coming up in quick internet searches for home cooking, though I see some mentions for commercial applications, but one could easily get one custom cut from a metal shop. And since it wouldn't come in contact with food, it shouldn't be a concern for those who avoid aluminum cookware.)

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