I don't have an IR thermometer, nor do I plan to carry out the experiment you suggest. However I have placed silicone rubber pads on the cooktop under a pan being heated. This was a suggestion of kaseki on this forum. High temperature silicone rubber will withstnd temps up to about 500F. With the pan on the largest hob (max power of 3.3 kW NOT on boost), and the power level set to about 7 or 8 (max = 10), I got the temperature high enough within 1-2 minutes for the rubber to show signs of breakdown (dark brown marks, slight change in viscosity). I would guess that was close to 500F. I've also done this with one of the smaller hobs, power around 2 kW, with slightly longer time to get to the breakdown temperature, perhaps 3-4 minutes.

I have also put a pan with corn oil on my large hob, set to somewhere around 8-9, again not on boost. It reached the smoke point of about 450F in around one minute. I was afraid the oil would ignite.

I have absolutely no doubt the cooktop can put out enough power to reach 500+F. I have never tried to heat an empty pan using boost, but the large hob will bring 8 qts of water to full rolling boil in under 5 minutes at max power of 4.6 kW. I got this cooktop precisely because of its power.

Cheryl

This post was edited by jadeite on Fri, Dec 7, 12 at 1:29

I've ignited a paper towel under a cast iron dutch oven. Is that hot enough to sear a steak?

That wasn't a high power cooktop though. It was a vintage Kenmore induction unit (made in Japan).

It can get hot enough in under a minute to be able to destroy the seasoning on a cast iron pan. This isn't a "turn it on and walk away while it's heating" type of cooking. You don't need to pre-heat for minutes. Just seconds. You may need to adjust your cooking pre-op to deal with the power of induction. It ain't gas. If you did what you are proposing, walk away with an empty skillet on the hob, you'd come back to a cracked cooktop. There wouldn't be anything in the skillet to absorb the heat generated like a pot of water has. You'd get to the danger zone quickly.

Look at it this way, PeterH2.

Just about any site on the net, mentions figures of about 38-40% of the energy from a gas burner actually goes into the pot or pan. Induction is usually quoted at about 84%.

Lets just go with 40% & 80%. So with induction you are going to at least double the energy that will be inflicted upon the pot or pan.

With my induction unit, most mormal cooking is done with the controls set from 2.5 to 4 (out of a 1- 11 range), 11 being boost (Elux actually calls it a "P" on the display.

The only time we turn it past 4 is to quickly boil water and then even on 8, it does not take long to boil the water and its usually boiling briskly before I'm ready, but then again I'm old!

As Cheryl mentions,
One has to rethink the timing processes,
(Paraphrasing) when using induction.
(An example), wife "Almost" burned the butter she was using to brown a porkchop, She had turned the cooktop up a bit, She Yawned and almost burnt the butter, things happen in seconds, instead of minutes with Induction.

Anyway, a long way of saying, "YEP!!!" "You can have your charred steak with induction"---Just be careful or you "May" get it "Flambed" Too!!!!

Gary

Of course you can heat an empty pan on an induction cooktop! You want to be careful about applying high power to a cold cast iron pan so it won't crack but the cooktop won't care.

I've added seasoning to cast iron on induction cooktops (hence the paper towel incident--don't do that) which requires a long, high temperature, empty pot cook. (Yes, real seasoning, the kind that takes EZ-off or a self-clean oven cycle to remove.)

fori - to ignite paper spontaneously requires temps of 451F, so that's the temperature your cooktop reached. I've also done this by putting paper towels under a pan. Lots of people say you can minimize spatter clean up by doing this. I don't know what they're doing, but once I got my pan hot enough to start stir frying, the paper was on fire! It made quite a mess, with little droplets of oil spatter combined with the charred remains of the paper.

I went on to try putting a sheet of silicone rubber (a large silpat) under the pan with similar results. I pulled everything off before the silicone started to smoke. That was it for the quick clean up approach. We just wipe up spatter with towels now, it's safer and almost as quick.

One point that no-one has mentioned yet, is that AFTER you've seared or stir-fried, and you turn the cooktop OFF, it cools down almost immediately. The only heat is from the cooking pan. There is no residual heat from the surround. I really like this aspect of induction as (1) I don't burn myself on hot metal grates (have many scars from the past); (2) I don't have to haul the hot pan away from the hob to avoid overcooking. I stir fry and sear a lot, so anything that gives me greater control with more safety is a big plus.

Cheryl

PeterH2:

As you have an IR thermometer and a CI pan to hand, how about taking them to that place where you saw the induction cooktop demo and getting them to run that test for you? If the store will cooperate, that will not only tell you if you can set the CI pan to 550F but also will disclose if you get the same buzzing with a CI pan that you heard with the SS pan in the previous demo.

As for using silicon mats or paper under a pan, that's for things like deep fat frying and candy-making where your cooking temps should be well below 450F. It is particularly useful for avoiding hot sugary drips which, cool cooktop or no, can stick like crazy to the surface and can result in pitting if not cleaned relatively promptly. I think I recall a couple of threads that discuss this subject within the last few months. I believe that there was another, similar one over at chowhound, too for anybody interested in further reading on the topic.

This post was edited by JWVideo on Fri, Dec 7, 12 at 12:35

I don't have an IR thermometer, but I've certainly ruined cheap Teflon pans through overheating and I carmelize sugar from time to time (mid 300s F). I'm not skilled enough to cook without charring at the top power levels. I usually sear at 7 out of 9. The boost function is for boiling water for me.

"I've ignited a paper towel under a cast iron dutch oven."

Only about 451 F.

Obviously, if the temperature that a pan is to be operated at is higher than the auto-ignition temperature of paper, then paper is a poor choice for keeping the pan off of the ceram. Similarly, silicone rubber (or Viton rubber) should not be used above its stable high temperature limit.

The question of just what to use is an interesting one. Ideally, the pan spacer should not ignite, not react with or otherwise damage the ceram, and have low thermal conductivity. At the moment, the only non-exotic materials that come to mine are glass, redwood, and ipe.

The possible interaction of glass and ceram is an unknown to me. Thin disks of fused silica might work, but approach the exotic category, and probably would conduct too much heat.

Redwood only chars in a fire, so it should resist the hot pan for some time. A thin piece would be required to keep from spacing the pan too high above the induction field coils.

Ipe is reportedly not burnable, but I have no direct experience. It probably chars.

Ceramic mat material, such as is used for protecting objects near propane torches, might be ok. The earlier solution, asbestos matting, might be difficult to obtain.

It would be a science experiment for any of these, but judging from the comments above, you all are up for it.

kas

All true science fiction buffs know that Fahrenheit 451 is the ignition point for paper (eponymous novel by Ray Bradbury).

I never doubted that induction is technically capable of putting enough energy into a pan to get it hotter than I need; the question was how aggressive the automatic safety cut-off devices are. IOW, would a cooktop simply shut off before hitting 550F? I had received the impression that it would, but on another thread JWVideo said his(?) CookTek unit can run a pan plenty hot, so I was looking for some actual numbers.

> If you did what you are proposing, walk away with an empty skillet on the hob

I never 'proposed' any such thing. That said, it's clear from comments here that induction requires more care than I had realized, when 'pushing the limits'.

Here is a link that might be useful: Fahrenheit 451

It requires more care because it is extremely fast.

> It requires more care because it is extremely fast.

No, it's because it's delicate compared to a pro-style gas range - if I had asked owners of pro-style gas ranges to heat an empty pan, no-one would have been worrying about destroying the range. Not because the gas range heats slower, but because the gas range is a fairly crude assembly of cast iron and steel that can withstand more abuse.

To give another example, I was reading the instructions for a couple of induction cooktops and I see dire warnings about rough pans, salt, and even sugar being able to scratch the surface.

I don't view these as significant flaws, just things to be mindful of. We lived for years with an electric smoothtop without hurting it, and we don't "baby" appliances. I seriously doubt we would damage an induction cooktop in real life.

Ok, so I was at Home Depot this afternoon and there was a marked down Ryobi IR thermometer.

I got a CI pan to 550 in under a minute with no problem other than the smoke coming from the seasoning. The cooktop didn't shut down, the top didn't crack, etc. i will have to reseason the pan.... The thermometer only goes up to 600 F, so I can't tell you the maximum temperature that the cooktop will hit. Of course, for the cool down, I left the pan sitting on the burner.

My cooktop is the cheaper, lower power Kenmore Elite. It was installed 7 years and 2 days ago. I do nothing to protect it from scratches and although the stainless steel frame looks a little battered, the glass is pristine. Occasionally I need to use a little Weiman's Cooktop Cleaner to clean a little haze off the heating elements, but otherwise, it's just multi-surface cleaner and a wipe.

The Dupont website says that Teflon begins to break down at 660 F. Been there, done that.

I think it comes down to the induction cooktop provides more energy to cook with. They will do exactly what you want with searing.

This post was edited by stahlee on Sat, Dec 8, 12 at 0:35

I had neglected teflon, but it is not too exotic to consider (being available from plastics suppliers). One-sixteenth inch pads of teflon should work for spacing out a 550F pan. This would require some care to not let the pan get into the 600F range though.

I just checked my cooktop's instruction manual and it doesn't seem to provide any listing of what temperature is sufficient to shut down a hob.

kas

For the benefit of future readers, I edited my list of negatives on the other thread to indicate the findings of folks here.

Peter, I also edited my last message here because I wasn't happy with what I wrote. Just in case people had read what I typed up.

You are aware that induction furnaces are used to melt stainless steel to about 2000*F?

I had two 12" frying pans going on this past Saturday nite for latkes. Not terribly hot. But to prevent all splatters, I first put newspapers down covering the cooktop, It was annoying to me to not be able to see the circle within which the pans were to be used. ( It would not make a big difference, as I often cook eggs in a little pan without looking at all. I just put the egg pan in the close general direction of the hob. And I cannot define 'close general direction'!)

But when two guests wanted to fry the latkes, I pulled the newspaper off, as it was annoying. I suppose I could have used small square silicone potholders, but I was anxious to have dinner come together smoothly, and I didn't think of the silicone, and I didn't really like giving up my frypan duties, control actually.

This is all to say that I don't think I'd like placing anything on the cooktop other than a cooking vessel. I was warned about salt and sugar scratching and I am pretty careful. I'm anal enough to dislike when dh salts his food and salt scatters on the table. Does he do it on purpose to show me what a 'devil may care' fellow he's become?

Silicone or whatever pads will allow a good view of the hob marking circles. Once the pan is aligned on a circle, a suitable paper with a pan-sized hole in it can be placed over the pan and used to collect splatter. Or just wipe it up afterwards. The hob circle will be cooler with the pads spacing the pan off of it.

kas

Here's a video of a beautifully seared steak cooked on induction.

Here is a link that might be useful: Wagyu Steak

Just to reiterahte for anyone thinking about induction - although many people protect their cooktops with Silpats, etc., there is no need to do this. These cooktops are very tough and hard to scratch. I have never used any sort of protection and have had no scratching after 7 years.

jxbrown - kaseki's suggestion to use silicone pads isn't so much to protect the surface, it's to stop the cooktop from overheating. But so far I have yet to have the cooktop shut down, so perhaps it isn't necessary. As you point out, even at 600F it was still putting out heat.

Cheryl

I had several reasons. Reduced potential for scratching was one (jiggling cast iron might scratch the surface -- smooth stainless steel might not), cooler hob surface to avoid spill hardening was another (wipe ups can be immediate), and stability for the occasional not-perfectly-flat pan was a third. The latter factor is best served by using three small pads, as three points define a plane.

kas

I realize that there are many reasons to use silicon padding, but I just wanted to reassure people that the cooktop will function perfectly and will be quite durable without doing anything special. I use elderly cast iron all the time without a problem. Additionally, you most certainly can use high heat without a problem. I would be inclined to chuck any pan that didn't sit flat, myself. However, if the cooktop is your baby and you want to pamper it, go for it!

I have only had my cooktop shut down once because of heat. I put an empty pan on it to heat, wandered off and forgot the pan. I have never had the sucker shut down while cooking other than when I slopped water on the controls. You learn to cook with a nearby towel. Fortunately there's no chance of lighting the towel on fire.

"You are aware that induction furnaces are used to melt stainless steel to about 2000*F?"

With a lot more power than a kitchen hob.

At some point the iron will not be magnetic enough to heat further (AKA Curie temperature, around 1400 F for iron, but lower for many other steels (500C to 600C, or 932F to 1112F).

How the hob will react to this would be interesting.
The metal becomes essentially non-magnetic.

> Here's a video of a beautifully seared steak cooked on induction.

He's using a non-stick pan, so I hope he kept the temperature well below 500F, which precludes a good sear. and, indeed, the steak does not appear to have a good sear on it.

Westsider40, I'm in total agreement. It's a good show to be able to put newspaper or silicone over the cooktop while doing something messy, but it's darned annoying. I go commando on mine, and put up with having to wipe it down with a soapy rag and polish off with a microfiber. It's worth the 2 minutes or so it might take me. :-)

Cj

I think he said he was using semame oil, which reportedly has a smoke point of 450F. As I didn't see any smoke, he probably kept the temperature a bit below that. He also mopped it up with a paper towell, it looked like, so clearly the temperature was below 451F. :)

kas

I have a question about the grease splatters- I get terrible grease splatters all over my cooktop but I always figured it was because I have NO venting. I don't get grease anywhere else so I figured the grease on my cooktop would be in my vent hood if I had one. Are you guys getting grease splatters even with good venting? I was looking forward to good venting in my next kitchen for this very reason...

I have a 7-year-old Kenmore Elite induction and the surface has held up great. I just have a few chips on the edges, actually.

brickeyee opined:

>At some point the iron will not be magnetic enough to heat
>further (AKA Curie temperature, around 1400 F for iron, but
>lower for many other steels (500C to 600C, or 932F to 1112F).

Someone (All Clad? Demeyere?) makes a pan with an intentional Curie temperature to avoid pan damage -- quite an elegant feature, but maybe not worth the tariff.

> He's using a non-stick pan, so I hope he kept the temperature well below 500F, which precludes a good sear. and, indeed, the steak does not appear to have a good sear on it.

Or he's using a Scanpan whish is (expensive!) non-stick which will tolerate high heat and you can't see the smoke from the oil. ;)

This post was edited by jxbrown on Wed, Dec 12, 12 at 12:42

"How the hob will react to this would be interesting.
The metal becomes essentially non-magnetic. "

Hobs have magnetic sensors to ensure that most of the power input into the hob coils is transfered to a pan that is at least partially made with a sufficiently high mu metal with adequate but lower conductivity than copper or aluminum. Certain stainless steels meet this requirement and can be easily sensed with a magnetic sensor.

Induction per se, however, only requires that a conductor intercept a changing magnetic field. For example, one can use induction to float aluminum above an induction field coil. (The aluminum gets very hot.) The currents induced into the aluminum generate their own field that reacts against the "hob" field like two north poles of two magnets push against each other. Copper can be floated this way also, and it gets even hotter. BTDT

In cases where the heat degrades the magnetizability of the steel, it won't matter to an induction furnace. On the other hand, if the heat degrades the mu of the iron, then depending on configuration, fewer field lines will pass through the iron and the power transfer will be less. This could overheat the induction coils, although I would not be surprised if they are water cooled in industrial applications.

In summary, iron is more efficient to inductively heat than aluminum or copper because the iron conductivity is lower than the conductivity of the copper used to make the hob coils. Inductively heating aluminum pans might be feasible if gold wire were affordable, or super-conductive wire were used with attendant cryocooling. (This would give new meaning to "high-end.")

kas

Couple of things, Peter.

For me, the point of cooking, searing the steak in this case, is the result and not the journey. Flames don't matter.

1. The chef in the Elux video said that he'd cook the steak on 7, 8 or 9. That's high

2. He seared the steak BUT there was no drama.
3. There was smoke,-see the video beginning at 4:00
4. Most or all of my induction ready cookware state that cooking should be done at low to medium.
5. To sear or brown meat, preheat the pan on medium for 1 minute.

That's it. No flames, no drama, no swirling.

Did you notice how perfectly even the crust was on the steak in the elux video? My gas range, in my vacation house, does not cook that evenly.

I also think that it was interesting that elux chef used a drop of oil v. Kenji of Serious Eats putting lots of oil in the frypan. I certainly respect Kenji.

Induction cooking is different and some folks just like to cook in the same fashion as their ancestors, parents, grandma, etc. It's what they're used to-it gives them comfort. Others will tackle something new if they believe there are benefits.

Cast iron can be used on higher heat. One of the beauties of induction is it's ability to change temps instantly, much like gas. But cast iron retains heat and does not change temp as quickly as other materials.

I understand your curiosity about induction.

ScanPan's induction pan has a silver handle, and the handle in the E'lux video was black. So I don't think its ScanPan. Maybe the swiss diamond?

I realize this is a old thread, but I've done some recent experimenting with me GE Cafe induction cooktop (2016 model).

Firsr, virtually all induction cooktops have a thermal cut off. this is often called "empty pan detection". using a laser thermometer capable of reading temps north of 1300 f, I determined the cut off for my cooktop is 750 f.

I was able to circumvent this cut off using a simple ceramic tile. placed under the cast iron skillet, it acts as an insulator. my skillet reached a temp of 900 f before I got scared and stopped - but it was still climbing at a rate of about 1 degree per second.

the ceramic tile hit a temp of 470 f. I suspect reducing the surface area of the ceramic touching the skillet will help keep it even cooler. I'm making a ceramic "ring" our of decorative penny sized ceramic tiles.

lastly, the cooktop surface hit a Max temp of 360... and that was just from the air beneath the skillet being heated radiantly.

a skillet this hot will sear a steak in 5 seconds... but burn it in 10, so yeah... heh.

Seems like you are on your way to developing an induction salamander.

Also, to correct a potentially misleading comment of mine back in the day that may be found above, the sophisticated way of confirming that an induction suitable pan is above the coils is to use the coils themselves as a sensor by detecting the "ring-down" rate of pulses put into the coil. This avoids including a single purpose magnetic sensor for each hob, and is not degraded by temperature as a Hall-effect or similar such sensor would be.

This is probably a dumb question.....will a slightly warped carbon steel pan work on induction? We are building a house and my cooktop will be induction. I bought the carbon steel pan a couple of years ago knowing I could use it with induction. What I didn't realize is that it is not unusual for carbon steel to warp. In our rental house we have an electric cooktop (yuck) and it doesn't work so great on it, lol.

Seems like the magnetic field would diminish over distance but maybe not enough that my slightly warped pan won't work?

I think a warped pan will indeed give you trouble. You need a flat bottom making contact with the hob.

Contact with the glass has nothing to do with induction. Which involves generating a magnetic field using the coils below the glass. So your pan will work fine. Contact with the glass is more important with a regular electric glass top but still not essential because that top gets to 750* plus and can still heat a pan.

I agree with dan1888 that a slightly warped carbon steel skillet will mostly work in the sense that perfect contact is not required for induction. The distances are not great enough to keep a warped pan from working.

But the pan will be sitting on a ceramic smoothtop surface. Depending on how the pan warped, an uneven base might make make the pan prone to spinning, sliding around etc. That difficulty can be fixed with silicon or paper spacers (as described previously by Kaseki and others above) or even with a dish towel under the pan. Of course, those strategies do limit how hot you make the pan. Very high heats (say 500°F) may scorch or ignite or melt a spacer.

However, depending on how warped the pan base and how "perfect" you need things to turn out, you might find the warp causes uneven pooling of oil and fats, pancake batters. omelettes. and etc. This will be true on any cooking surface as well as with oven use.

Thank you for your replies. Looking forward to induction!

Yes, the warping does cause pooling so I have to move the food around, etc. I love the way the pan cooks but very disappointed that it warped.

Do you know how easily that warp can be fixed? You can find DIY instructions by typing "how to flatten a warped carbon steel pan" in your search engine of choice. If DIY hammering isn't your thing, check with metal fabrication shops (such as one that makes wrought iron railings), Also look for blacksmiths, farriers, auto-body shops, or machine shops. FWIW, the metal fabrication shop in my rural town charges $10 to $20 depending on the thickness of the CS pan.

If the pan is not terribly warped, how about placing it on a silicon mat?

I've seen the DIY videos and may give it a try once we get moved into our new house and have access to our "stuff" again. Thanks for the idea about fabrication shops.

Rita, maybe I can do a silicone donut mat around the high center! That would work for sauteing. One reason I got the pan was to be able to crank up the heat for a good sear so the mat may melt. But for other uses, that just may work!

If you're going to get it THAT hot, remember that silicon can melt near 500*. And that silicon slag is hard to remove.

Thanks, yep, no high heat for silicone mats!