Meekah was kind enough to donate her 8" All-Clad G5 (“G” for graphite, “5” for the SS-A-G-A-SS layup) for testing. What I hope will follow in this thread is a piecemeal evaluation of the pan’s strengths and weaknesses, features and foibles.
In this Episode 1, I ran some tests intended to assess All-Clad’s brags about how tremendously responsive G5 is. In my parsings of that particular brag, I conclude A-C bases it on the intrinsic, astonishingly high thermal conductivity of the very thin center layer of graphite in the pan’s core (probaby around 1,800W/mK). I also wanted to test and quantify the effect of “carryover heat” from various hobs on downward responsiveness.
Specifically, in this first responsiveness test, I wanted to see how fast G5 cools on its own, and then compare that with the times when the pan is left on deactivated hobs after the heat is cut. Yesterday I did that first run (just taken of the heat to air cool), plus on induction and gas hobs. In Episode 2, I’ll do the same for open resistive coil and radiant.
I set the pan containing 500ml of water on the hobs to attain a constant 180F, on the verge of simmer, on induction, and then gas, hobs. The glass and grate were as hot as they were going to get. Then I killed the power/gas without moving the pan, and timed how long it took for that 500ml to shed 80F in open air.
The G5 was first removed from the hob and placed on a wire cooling rack. The time to drop to 100F was then measured to be 23:33.
On induction, the pan’s water dropped back to 100F in 28:29.
On gas, it dipped to 100F in 26:14.
One conclusion here is that even this (allegedly) “lightning fast” G5 pan isn’t very downwardly responsive with ½ liter of water or moist food in it, no matter what you cook on.
This is true even if you remove the pan altogether. I think swaddling anything in SS is going to dramatically slow downward response.
Another conclusion is that there is enough heat stored in flat glass in full contact with the pan (along with its insulation value) to slow the cooling considerably. On my vented induction hob, the G5 held the heat by about 5 minutes longer than air cooling.
A third conclusion is that my gas grate didn’t hold as much heat, or slow the G5’s cooling, by as much as I expected it would. I attribute this to a couple factors. First, this particular grate is stainless steel, and so would not conduct heat back to the pan as fast as would have cast iron. Second, it’s round in cross section, meaning there is only a minuscule area of actual contact between it and the pan bottom (probably less than with the close-mesh cooling rack). Third and conversely, there was ample air circulation. Whatever heat the grate added slowed cooling by less than 3 minutes compared with no added heat at all. When I get time, I’ll repeat the test using a hob with a cast iron grate, but that grate is also open-center with minimal surface contact with pans, especially one this small. Obviously, grates that are massive and/or make a lot of surface contact would likely conduct enough more heat to lengthen cooling times.
I also think that if the pan was preheated very fast using maximum heat, the glass and the grates (maybe not the coils) would not have stored as much heat. For example, remember the parlor trick the appliance stores used when induction appliances first came to market? They’d take a skillet, sawn in half, and fast-fry an egg in it, while an ice cube sat unmelted on the glass a few inches away. It’s not that the glass doesn’t get hot, it’s that the glass hadn’t had time to be heated by the pan. In this test, the glass over the induction hob attained 167F, and after 5 minutes without power, was still at 118F.
Coil and radiant data to follow…
