Not quite paper-thin foil, but may be I should un-retire my aluminum kettle.
Your criticism is baseless. âRolling boilâ is subjective. What is rolling boil to one person is not a rolling boil to another person. The definition is not even the same for the same person on a different day. As for CenturyLifeâs temperature usage, it is fine. Look at his plot. The two end points are the same for the two pots measured by the two temperature probes. This means there is no significant difference between the two probes. The two probes agree at room temperature, and the two probes agree at boiling temperature.
Error bars for what? As it is, the two plots are already overlying each other â indicate there is no difference. Error bars are only important when there appears to be a difference, and yet you are not sure if the difference is within margin of error or not. For him to put error bars add absolutely no value. Without error bar, the two plots are overlapping. With error bars, the two plots are only MORE overlapping. It does not change the conclusion.
If error bars are needed (which it not needed in this case), then he can just use the precision value from the manufacturer.
And you know how to do it the right way?
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PhilD,
He supposed that the 200 degrees end point was the same every time. Itâs not.
He needs to establish how much error there is in reaching that endpoint by correlating multiple measures before beginning his study to establish reliability.
But itâs pseudo science anyway. Just using a very subjective criterion for boiling and an inch of water, I was able to find out the same thing without doing an âexperiment.â
Ray
Yes, Chem,
I know how to do it the right way.
Ray
I know what you mean, sck,
Iâve got this 60âs era SS whistling teapot . . . . .
Ray
Youâre missing the point. My conclusion was that there is no significant difference in boiling speeds at 2L. Even at 3.5L or 4 quarts the difference is quite small. Adding error bars would only strengthen that conclusion.
Water boiling temperature is well known; mainly you just need to adjust for altitude. I used a thermometer (accurate to 0.1 degrees F) calibrated against ice water and Anova Precision sous vide devices which are themselves rated to be accurate to 0.01 degrees F. I also did multiple runs per pot/boil combinationâthese tests are repeatable. And youâre misinterpreting the endpoints (for easier readability, I cut off a curve once the pot reached boiling temperature because adding a flat line at ~212F doesnât add more information and just adds clutter) even though I have been transparent in my methodology but itâs true that I could be even more transparent, so here goes:
Due to water convection currents (leading to unevenness within the water) and the coarseness of the time intervals, the curve might not look as smooth as one would like, but thatâs what experimental data looks like. Real life is messy, not a perfectly smooth curve. Furthermore, do you think I donât know about convection currents? I only considered it a solid boil if it could hold that temperature for several seconds (I think it was 15 or 30 seconds; I donât have my notes with me right now). That kind of consistency shows that itâs not a temperature spike that goes back down.
Iâll take my methodology (themometer measurement) any day of the week over your proposed methodology, which is to stare at a boiling pot of water until you subjectively think itâs boiling.
Franz,
You didnât even need to do a study to reach those conclusions. Seitan and I both came to the same conclusions before you posted on this thread. Seitan did a pretty good informal studyâpictures and everything.
Whatâs to be gained by debating experimental design?
We all agree on what matters in the kitchen, so letâs leave it at that.
Ray
No. The actual heating surface in an induced pan is quite thin, and rarely is this surface in direct contact with the food. If it were, you would have terrible scorching and hotspotting.
In your kettle, the heat is generated in an inner wire, which is also not in direct contact with the water. That wire is surrounded by ceramic insulation. Then thereâs an outer layer of metalâthatâs whatâs in contact with the water.
Moreover, in many modern kettles, this 3-layer element is further removed from the water-- a cap sits atop the element. This is intended to prevent limescale accumulation
Franz, youâre wasting your time defending the unassailableâŚ
Maybe because you were the one who bought up the fact that his experimental design is fault: temperature not being a good parameter and he doesnât have measurement errorsâŚetc? It is amazing that now he is not allowed to defend his design, but it was for you to attack it.
Chem,
It is unfortunate that you (or Franz) take my comments as personal attacksâand Iâm pleased that we have all come to an agreement on alternate pieces of cookware and time to boil water.
Franz has a practical attitude toward cookware and does us all a service with his website, and contributions to our blog. Nevertheless, his specialty is clearly not experimental design, and there are many alternative ways to approach measurement in cooking tasks that could lead us to different conclusions.
Whether or not you think that is true, itâs clear to me that this is not an appropriate forum for discussions of scientific research design.
Ray
It is even less fortunate that you think he shouldnât respond to your criticism. First, it is an attack for sure (personal or not). As such, he has the right to respond. Period.
For you to criticize his experiment, and when he tried to explain his rationale, you went on the âYour experiment is still wrong, but please donât explain itâ is simply very poor form.
Again, you are doing this here. It is ok for you to criticize his scientific research design, but it is not ok for him to explain. If this is not the right forum for such discussion, then why did you bring it up. Perhaps you should apologize for bringing it up in the first place . Instead, you kept on slipping out these one last attack lines:
âhis specialty is clearly not experimental designâ or " itâs pseudo science anyway. Just using a very subjective criterion for boiling and an inch of water, I was able to find out the same thing without doing an âexperiment.â
Then say that this is not the correct forum to discuss experiment. Who was the person bringing up experiment design in the first place? You.
You are not a physical scientist or engineer, so you should not lecture people what is a good experimental design. For one, your criticism of his lack of âerror barâ made no sense at all. You should read a little bit more about statistic and null hypothesis
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Iâm sorry but I canât resist.
It looks like we have a flame war hereâŚ
about flame.
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Sorry you feel that way, Chem.
Letâs move on.
Ray
Wait for it:⌠âIâm just a home cook, having fun. Wheee!â
That surprises me I though induction heated up all the ferrous material in the pan. which in a SS pan is the whole base and is in contact with food. Hence the need for good quality bases to avoid hot spots and distortion. I tried some simple SS mixing bowls when making a hollandaise sauce and they definitely arenât as even.
Understood that the kettle element has a number of layers but the element is immersed in the water unlike a coil heater (similar construction) sitting under a pan than needs to heat the pan first.
No. The thickness of the layer that actually heats in an induction field depends on the skin depth of the particular material. It is no coincidence that induction-compatible pans usually have only a very thin, outer ferromagnetic layer. The evenness you experienced in contrast to the mixing bowls has more to do with the conduction of heat past the skin than it does the field.
As I said, many modern kettles do not immerse the coils at all. Some do. But those that do still depend on conduction to heat the water. Immersion makes for very good thermal contact, and the enclosed nature of the kettle speeds the boil along. But if you thermally glued a similarly-constructed/insulated kettle to your coil hob, youâd see very close to the same result.
Aloha,
Kaleo
Thanks - that makes sense or else you would need to calibrate your hob for the size of your bottom. I suppose in theory it would make them even faster if you could set the target to a wider bottom.
I do have another set of really cheap steel pans that donât work at all - very thin bases - i assume they are not thick enough to engage the induction. That said my cheap and cheery non-stick wok is quite thin and light and it works fine. Odd.
Youâre welcome. Does your cheap steel set attract a magnet?
Thanks very much for your reply Franz.
I hadnât checked this topic for a few days and didnât realize this discussion had come to a rolling boil :-).
Given the common understanding that copper is more than twice as conductive as aluminum, the null hypothesis for a boiling water test would be that a copper disc or clad vessel would bring water to a boil faster. Thatâs why the results showing this not to be the case seems counter intuitive. It sounds like the reason for this has something to do with the effects of water convection dwarfing the effects of pan material, but I confess I donât quite understand what exactly this means and how it plays out in a causal chain.
As for water quantity, I found that a simple reduction by half an inch of water volume produced a reduction in boiling time by two minutes. That seems significant to me.
Finally, I agree, that watching water to determine a boiling point just seems arbitrary and unreliable.
