Why do my frying pans warp?

[MarKoz]

Why do my frying pans warp? I preheat my frying pans with a Cooper grill surface thermometer placed directly on the cooking surface. When the pan gets to 400 degrees I put the meat in to sear it. I have a glass top electric range and use good quality cookware (Vollrath Tribute). When I preheat the pans the heat control is turned to 6/10. What can I do to get a good sear on an electric range without warping my pans? I have considered preheating the pan to a lower temperature then putting in the meat and jacking up the temperature but electric stoves just don't respond that quickly. Any ideas?

[jljohn]

I know there is a lot of the "that shouldn't happen" sentiment here, but I have never, and I really mean never, used a tri-ply (or more-ply) pan that didn't warp with use. You have multiple materials with differing coefficients of linear expansion being heated from one side and cooled from one side (like when ingredients are added to the pan) and over time it will cause warping. The advice never to place a hot pan in cold water is good, but it won't prevent the eventual warping. I, for one, believe it to be inevitable. Your best bet is to get single material (or simply coated single material) pans if warping is a major concern.

[Chemicalkinetics]

<You have multiple materials with differing coefficients of linear expansion being heated from one side and cooled from one side (like when ingredients are added to the pan) and over time it will cause warping.>

That is not why they warp. Pure aluminum pans actually are very easy to warp, more so than cladded cookware.

[MarKoz]

Thank-you to everyone for the helpful replies. Lots of good points made and the metallurgy lesson is fascinating. From the aggregate responses it sounds like an unfortunate combination of using a glass top stove and "clad" cookware. These pans did not warp very much and would be perfectly usable on a gas range. Although the warp is subtle they spin like tops if you don't hold the handles while you stir.

To the people who are wondering if i subjected the pans to a temperature shock I can safely say that is not the case.

I have noticed that my pans with a heavy slab of aluminium welded to the bottom have not warped over time. Guess I will stick with those from now on.

[Chemicalkinetics]

<These pans did not warp very much and would be perfectly usable on a gas range>

Just want to reiterate this point again, they will also work fine on electric coil stove.

< if i subjected the pans to a temperature shock I can safely say that is not the case.>

We all do. It is just to different degree.

<a heavy slab of aluminium welded to the bottom have>

Yes, disc bottom clad tends to be much thicker and much better at resisting warping.

[grampart]

I never knew how many warped pots and pans we had until we got our first (and last) glass top range.

[Chemicalkinetics]

Agree. Many pots and pans have small degree of warping. It is usually not a problem for gas stoves or electric coil stoves, but it is a big deal for flat glass top. In fact, most cookware in professional kitchens are warped.

[MarKoz]

A glass top stove is not my first choice but gas isn't an option for me.

[3MTA3]

I'LL say it again: "first AND last glass top stove"
That said, induction cook tops are also flat. Even a slightly uneven vessel will have hot/cold spots

[mikie]

Two of my girls have had or have glass top stoves and like you, it's the last one. All of their pans have terribly warped bottoms and spin at will. I have always attributed this to the slow thermal response and the hurry to get the pan hot, so they turn it up too high before the food goes in. This may or may not be the case, but I know they are always in a hurry. I cook more slowly and enjoy the time, even with gas, I don't go to full heat initally, rather ramp it up until I'm ready to put the oil in and then ramp it up just a bit more until the oil shimmers, then the food goes in.

[MarKoz]

As I mentioned in the original post, the burner was set to 6/10 to preheat the pan.

[mikie]

Pardon me, I didn't mean to imply you overheated the pans, only that my daughters overheated their pans and I attributed that to the glass top stoves, since that's when it happened and I figured it was because they were, as usual, in a hurry and not patient enough to use low to medium heat.

We have some old pans at our house that warped the opposite way. When you put oil in it all runs to the edge and leaves the middle dry. These wouldn't spin on a glass top, but they still don't cook well.

[MarKoz]

You, and everyone else here, are so polite! Love the site. Thanks for all your comments.

[Chemicalkinetics]

Warping does occur when the cookware goes through a quick heating and cooling cycle. Some materials are more prone than others. I would strongly suggest you to look into using cast iron cookware or very thick based cookware.

[GH1618]

There is a significant difference in coefficient of thermal expansion between Al and SS, and even between different types of SS. The higher the temperature of a multi-ply pan, the greater the stress due to this characteristic:

http://www.engineeringtoolbox.com/lin...

[kaleokahu]

Hi, MarKoz:

Hmmm... Are you using the pan on the full-sized hob(s)? When in the process are you adding your fat?

Unless you're subjecting the pan to a big thermal shock going back down, your pan should not warp at +/- 400F, or even 425 (the accuracy margin of your Cooper). Defective pan or bad design, I think.

As others have intimated, cast iron is unlikely to warp.

"[E]lectric stoves just don't respond that quickly." They're not the greatest, but in the UP direction, they're not bad.

You might try preheating your pan in the oven (along with turning on your hob), and then flop when you move it to the hob. Sort of the reverse of finishing in the oven. But you can still do that, too.

Aloha,
Kaleo

[petek]

<You might try preheating your pan in the oven (along with turning on your hob), and then flop when you move it to the hob. Sort of the reverse of finishing in the oven. But you can still do that, too.>

This is exactly what I do with my carbon steel pans,works great..

[fourunder]

If you wash or dip your hot pans in cold water....they will warp....

[MarKoz]

My pans have always cooled before I wash them.

[fourunder]

Are you putting cold liquid into a very hot pan?

[MarKoz]

Nope

[BIGGUNDOCTOR]

Hot pan, and cold meat. I have straightened stainless food conveyors by applying heat to one side, and cooling it with a wet rag-pulls it right over. Stainless is very squirrely when heat is applied. It moves a lot when I weld it, especially thinner sections.

When metal is heated it expands, when it is cooled it contracts, and if it is cooled unevenly the internal strain in the metal warps the shape.

[MarKoz]

The day my big pan warped I had 3 steaks in it that had sat out of the fridge 1 hour before being placed in a 275 degree oven for 30 minutes before searing in the pan.

Sounds like regular cooking puts a great deal of stress on metal. Another plus for gas heat where slight warps don't affect the performance (or so I'm told - I've never had the pleasure of cooking with gas).

[mikie]

Well, even on a gasrange you need a flat bottom to keep the oil evenly distributed over the bottom of the pan.

[GH1618]

High heat puts increased stress on the pan, not so much "regular" cooking.

Is the warp permanent, or does it return to original shape when cooled?

[mikie]

I can tell you my daughters warped pans are permanently warped. The bottoms look more like woks, well that's an exaggeration, but you get the point.

[MrsJonesey]

No expert here but I don't think they should be warping. Have you contacted Vollrath? I have a glass cooktop also. My carbon steel warped immediately. I called the company (don't recall the manufacturer) and they sent me a brand new one immediately.

[GH1618]

Is this tri-ply SS/Al/SS? It's not surprising to me that any similarly constructed pan would warp being heated from one side to high temperature. I think a carbon steel or all-aluminum pan is better suited to searing.

[MarKoz]

It is tri-ply "clad" style. I recently bought an uber-heavy Vollrath Intrigue brazier that has a 1/4" thick aluminium slab welded to the bottom and it seems to heat evenly and hasn't warped (yet). I always thought tri-ply was the holy grail. Perhaps not.

[chowser]

Try cast iron.

[wyogal]

What do you do when you are done cooking? Do you notice it warping when it is getting hot, or is it happening during a too quick cool down?

[MarKoz]

Happens during the heating phase. My 12" Tribute pan warped almost right away. The 14" is heavier gauge metal and lasted a couple of years before warping.