Join Date: Aug 2004
As Robo410 stated, there is a huge difference between adding a small amount of liquid to a pan, and immersing a very hot vessel into cold water. First, let's examine the reason that "thermal Shock destroys a pan, be it cast-iron, ceramic, glass, etc.
First, metal pans, with the exception of cast iron, can warp when subjected to rapid temperature changes. This is because they are subjected to the pressures of expansion and contraction. And actually, if the pans are of uniform thickness, they are less susceptable to warping if they are plunged ino water. This is because the entire metal will expand or contract at a uniform rate, allowing the pan to retain its shape. However, I have had pans bottoms warp because the applied heat cause rapiid expansion of the bottom sruface before the sides could expand in cercumference. This usually is not detrimental, and when the heat was removed, the pan bottom straightend back to its original shape. This happened because I did a foolish thing. I placed the sauce pan onto the gas flame with nothing in it to absorb the heat.
Glass, ceramic, cast-iron, and ceramic coated cast iron crack because these items are poor conductors of heat. The outermost surface rises or lowers in temperature much faster than do the inner and inside laryes of the material. This causes the outer molecular layer to change size before the inner layers have a chance to respond equally. Tremendous forces are exerted that would twist the material if it were elastic. But as thse materials are un-elastic, or brittle, they fail casostrophically, or shatter.
For further explanation, think of the trigger element in your electric toaster. It's calle a bi-metallic strip. It is made from two pieces of metal, cut into identicle strips, but from different metals, with different expansion characteristics. These materials are conductors and are place so that one end is connected to the ower source, while the other touches the power returen, of ground side of the circuit. As power flows into the heating coils, some of the radient heat causes the bi-metallic strip to heat up. As it does so, the two joined pieces of metal expand at different rates. As they are welded together into a single strip, this causes the strip to warp until the tip touching ground moves away and breaks the circuit. The result, no more current flow and the toaster shuts off. The stripp cools and returns to its original shape, again touching the ground side of the relay.
Now imagine that that rapidly expanding metal strip were molecularly joined to a piece of glass, and as it were heated, tried to force the glass to bend. Eventually, either the metal would break its bond with the glass, or the glass would break. This is what happens as the surface material shrinks or expands with relation to the inner structure of the material, be it glass, ceramic, cast-iron, or combination of materials.
So, if you are going to add liquid to hot cooking vessels, add it slowly so that it doesn't cool the pan too rapidly on too large an area, or add liquid that is close to the temperature of the pan. And remember, the greater the temperature difference, the more force that is exerted on the material.
In that same vein, if you are ever working with strong chemicals such as acid, with water, there is a chemical reaction that takes place. this causes heat. Some drain cleaners are hydrocloric acid based.
Acid does not absorb and dissipate heat redily and will react violently when water is added to it. Water, on the other hand, absorbs heat readily and boils off to maintain a safe temperature.
Thus, always pour acid into water, not the other way around. To pour water into acid can cause min-explosions that can throw the caustic acids into the air resulting in skin exposure (think chemical burns), or damage to other surfaces.
In all things, think about whay materials react the way they do, and how they react. Then, act accordingly.
Seeeeeya; Goodweed of the North
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