Unwarping a pot/saucepan with a thermal shock

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jistoy

Assistant Cook
Joined
Aug 31, 2021
Messages
2
Location
Finland
I have teflon saucepans which are in very good shape except they warp often (maybe once a week). With exact hammer hits (with medium power) and with the help of a ruler, I can straighten the bottom very accurately. But that's an annoying process involving lots of noise. So I'm wondering if there's a better way.

What happens is the bottom of the pan bulges out (downwards). I am not sure what causes that. Perhaps only cooking normally causes it. I do try to wait for some time before moving the pan into the sink which has some water droplets in the bottom, and in which some water could pour inside the pan even when it's not yet fully cooled down.

According to one source the warping is due to the pan consisting of different layers of different metals, plus coatings. So sudden cooldown would shrink certain metal quickly while the other metals would still stay expanded and hot and that would cause warping. However, I do not know exactly how this works and what metals are in the pan in which order. Also I don't know whether pans can have the metals in the opposite order, causing inverted warping. Also I don't know if the stretching happens by stretching the whole diameter or if the vertical component stretches as well.

Thinking about this, I'll just propose a theory for you to debunk (please correct my mistakes). Simplifying, I'll hypothesize that the pan consists of just one thick metal. Heating it up on the stove will cause even stretching, and essentially the diameter of the whole bottom will increase evenly. Now, pouring cold water on top will cause a thermal shock, and since hot metal reacts quickly to cold water, the top side of the bottom will react much quicker than the bottom side. So the upper side diameter shrinks while bottom side diameter cools down slower. This warps the whole bottom downwards. (Just a hypothesis.)

If this theory happens to be correct, then perhaps it's not possible to straighten the pan out of that situation with just stove heating plus water. Because as it's already substantially warped, adding cold water on the hot pan's flipside (bottom of the bottom) is not any more enough for unwarping (maybe with multiple treatments it could possibly work).

But, what if I simply end some of my cooking sessions by pouring cold water on the bottom of the bottom of a hot pan. Perhaps that would cause warping upwards, which is a wanted result since at least then the pan won't swing on the stove (in which situation an induction stove also has less effective contact on the pan).

Sorry for the long rambling, but what do you think? (I don't want to ruin my pans because they're expensive and good..)
 

msmofet

Chef Extraordinaire
Joined
Apr 5, 2009
Messages
13,059
Welcome to DC.


Sorry, I can't help with your problem. I do have cookie sheets and roasting pans that sometimes warp when in the oven, but they straighten out after they cool.
 

dragnlaw

Site Team
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Feb 16, 2013
Messages
7,542
Location
Waterdown, Ontario
Welcome to DC jistoy!

Wow! So you are saying ALL your pans are warping? and that they are high end, good quality? VERY bizarre I must say.

My first question is - Why are you pouring cold water into a hot pan?
2nd question - are you heating these pans dry/empty?
3rd - are you using extremely high heat all the time?
4th - are you using the correct size pan for the foods in it?

I know nothing of metals, their properties and actions. We have one or two members who will be able (I'm pretty sure) to answer your technical questions.

and Welcome again!
 

Andy M.

Certified Pretend Chef
Joined
Sep 1, 2004
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49,602
Location
Massachusetts
Improper use can cause warping.

However, if that's not the case, they could just be crappy pans. If they're aluminum or Teflon and aluminum, shop for a thicker pan.
 

Chief Longwind Of The North

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Aug 26, 2004
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USA,Michigan
It really depends on the pan material, the thickness of the pan, and how it is being used.

As you surmised metal, when heated expands, and contracts when cooled, as do all substances wit the exception of water. Pans made of aluminum, and copper are great conductors of heat, and transfer heat quickly enough that they resist warping, especially thicker, well made pots and pans. That said, if the pan bottom is very hot, and the sides are cooler, the expanding bottom will not be able to expand evenly due to the non-expanding sides. This can cause warping. SS pans are relatively poor conductors of heat, and so develop hot spots. Often times, the SS is bonded to aluminum, or copper to facilitate even heating, resisting the formation of hot spots. But again, the sides are usually cooler than is the cooking surface. Excessive heat can cause the pan to warp. Cast iron, is the poorest heat conductor of the metal pots and pans. Thermal shock can cause catastrophic failure, causing CI to shatter, like glass.

When a very cold liquid, or frozen veggies are add to a very hot pan, it will cause a rapid contraction of the metal, with the surrounding metal cooling more slowly. This can cause warpage. Once metal is warped, it is difficult to straighten back into shape. Use your pans correctly, and avoid warping issues in the first place.

Seeeeya; Chief Longwind of the North
 

jistoy

Assistant Cook
Joined
Aug 31, 2021
Messages
2
Location
Finland
Thanks for the answers! My answers:

Why are you pouring cold water into a hot pan?
= The warping has happened multiple times and I would say there have been times when I didn't do a single "mistake" between unwarping and warping again. Not even throwing frozen veggies in, which is a pretty convenient thing to do. So I'm not usually pouring cold water into a hot pan. Sometimes that might happen, to some extent (if I have to wash the pan for repeated use and don't want to wait 30 minutes for cooldown, but wait for minute only instead).

are you heating these pans dry/empty?
= No

are you using extremely high heat all the time?
= No

are you using the correct size pan for the foods in it?
= Yes

Thus it must sound like the pans are garbage then.. However, they are definitely at least in the mid price range if not more expensive. Aluminum body, some very durable teflon coat (already about 10 years old but the coating actually seems almost like new).

When pans warp, do they always warp downwards? Have you seen a pan warping upwards?

I guess my main question is has anyone ever succeeded at unwarping a pan with just heat plus cold water?
 

dragnlaw

Site Team
Staff member
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Messages
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Location
Waterdown, Ontario
lol.... still can't answer your question on warping, sorry.

It does sound as if you know a wee tad. Wish I could help more.

Other than low and slow.
 

jennyema

Chef Extraordinaire
Joined
Mar 1, 2002
Messages
10,467
Location
Boston and Cape Cod
Most teflon pans are thin and warp easily.

Look for a brand thats thicker on the bottom.

Problem is, the coating wears off. Thats why lots of us use stainless or cast iron and buy cheap nonstick pans and toss them when they warp or the coating wears down
 
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