# Why does plastic feel less cold/hot than glass or metal ? **URL:** \ **Category:** Factual Questions\ **Created:** [June 7, 2016, 9:14am UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720 "2016-06-07T09:14:01Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Les\_Espaces\_Du\_Sommeil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/les_espaces_du_sommeil/32/308_2.png) [@Les\_Espaces\_Du\_Sommeil](https://boards.straightdope.com/u/Les_Espaces_Du_Sommeil)\ **Post date:** [June 7, 2016, 9:14am UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/1 "2016-06-07T09:14:01Z")
This morning, while preparing beakfast, I picked a plastic box from the fridge and noticed that it felt… not cold to the touch. My first thought was that I may have left the fridge door ajar during the night but then I remembered that I’d had problem opening it because I had my hands already full. So, the door had been shut properly. I touched various things in the fridge (glass, metal) and they all felt cold but not the plastic ones. They felt somewhat lukewarm. This reminded me of something that I’ve noticed when I do the dishes: the glasses are almost too hot to handle and perfectly dry when I take them out of the dishwasher. Ditto for forks and knives. However I can grab the plastic bowls and cups comfortably and they are still dripping wet. Is it due to the physical properties of plastics ? ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 7, 2016, 9:20am UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/2 "2016-06-07T09:20:28Z")
Yes, specifically to their heat conductivity. Wood will also not feel as warm or cold as metal or glass, for the same reason: low heat conductivity. Both plastics and wood are insulators: they transmit heat badly. Objects with low heat conductivity are worse at absorbing or providing heat to your own hand than those with high values; what you’re noticing is not a difference in temperature but in energy flow. ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [June 7, 2016, 9:50am UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/3 "2016-06-07T09:50:09Z")
Also, a property related to conductivity, called thermal inertia is involved here. ---
**Author:** ![joema](https://avatars.discourse-cdn.com/v4/letter/j/a9adbd/32.png) [@joema](https://boards.straightdope.com/u/joema)\ **Post date:** [June 7, 2016, 11:29am UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/4 "2016-06-07T11:29:37Z")
> [@Nava](#): > > Yes, specifically to their heat conductivity. > > Wood will also not feel as warm or cold as metal or glass, for the same reason: low heat conductivity…what you’re noticing is not a difference in temperature but in energy flow. Likewise objects made from Titanium such as watch cases feel “warmer” because the heat conductivity is much lower than aluminum, steel or copper. Thermal conductivity (W/m-k) Copper: 386 Aluminum: 204 Titanium: 19-23 Hardwoods (oak, maple): 0.16 Space shuttle thermal tile: 0.05 > **[Metals, Metallic Elements and Alloys - Thermal Conductivities](https://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html)** > > Thermal conductivities of common metals, metallic elements aand alloys. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 7, 2016, 11:48am UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/5 "2016-06-07T11:48:24Z")
> [@ZurBob](#): > > Also, a property related to conductivity, called thermal inertia is involved here. This sums it up nicely. See [thermal inertia,](https://en.wikipedia.org/wiki/Volumetric_heat_capacity#Thermal_inertia) the equation for which includes the density, specific heat, and thermal conductivity of a material. Compared to plastics, metals have high densities and high thermal conductivities, so they tend to have much higher thermal inertias: for a given temperature, a piece of steel can dump more heat into your hand more quickly with less decrease in its own temperature than a piece of polyethylene at the same starting temperature (that “less decrease in its own temperature” is what the term “thermal inertia” is describing). Your hand really does get hotter holding the steel than it does holding the plastic. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [June 7, 2016, 12:37pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/6 "2016-06-07T12:37:48Z")
This is why plastic beer bottles are better than glass or aluminum for keeping your beer cold. Sent from my iPad using Tapatalk ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 7, 2016, 12:58pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/7 "2016-06-07T12:58:34Z")
> [@joema](#): > > Likewise objects made from Titanium such as watch cases feel “warmer” because the heat conductivity is much lower than aluminum, steel or copper. > > Thermal conductivity (W/m-k) > Copper: 386 > Aluminum: 204 > Titanium: 19-23 > Hardwoods (oak, maple): 0.16 > Space shuttle thermal tile: 0.05 > > [Metals, Metallic Elements and Alloys - Thermal Conductivities](http://www.engineeringtoolbox.com/thermal-conductivity-metals-d_858.html) > [@Machine\_Elf](#): > > This sums it up nicely. See [thermal inertia,](https://en.wikipedia.org/wiki/Volumetric_heat_capacity#Thermal_inertia) the equation for which includes the density, specific heat, and thermal conductivity of a material. Compared to plastics, metals have high densities and high thermal conductivities, so they tend to have much higher thermal inertias: for a given temperature, a piece of steel can dump more heat into your hand more quickly with less decrease in its own temperature than a piece of polyethylene at the same starting temperature (that “less decrease in its own temperature” is what the term “thermal inertia” is describing). Your hand really does get hotter holding the steel than it does holding the plastic. As both of these posts admirably show, now add cast iron (those kick ass behemoth pans), which hold heat, hold heat hotter, it just occurrs to me, than anything you normally find as kitchen equipment (I’m not sure which of the “iron” indexes in the cite of **joema**. High thermal conductivity and low inertia is why copper pans are the bomb–“oh shit the flame is too high…” and lower it: on a copper pan, instant relief; on cast-iron, the pan will stay blasting away for an eternity. ---
**Author:** ![Les\_Espaces\_Du\_Sommeil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/les_espaces_du_sommeil/32/308_2.png) [@Les\_Espaces\_Du\_Sommeil](https://boards.straightdope.com/u/Les_Espaces_Du_Sommeil)\ **Post date:** [June 7, 2016, 1:10pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/8 "2016-06-07T13:10:57Z")
Thanks for your answers. So, in layman’s terms, plastic objects are just as cold/hot as the other items in the fridge/dishwasher, just not as good as the metal/glass ones at transmitting it? ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 7, 2016, 1:14pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/9 "2016-06-07T13:14:06Z")
Yes. ---
**Author:** ![Les\_Espaces\_Du\_Sommeil](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/les_espaces_du_sommeil/32/308_2.png) [@Les\_Espaces\_Du\_Sommeil](https://boards.straightdope.com/u/Les_Espaces_Du_Sommeil)\ **Post date:** [June 7, 2016, 1:27pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/10 "2016-06-07T13:27:50Z")
It makes sense. Still, it’s funny how this phenomenon tricks our senses. I would have sworn that the various objects I touched this morning had very different temperatures. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 7, 2016, 1:33pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/11 "2016-06-07T13:33:45Z")
Well, the actual message from the senses is “thing A makes me cold/hot more/quicker than thing B”; it’s the interpretation that jumps from there to “thing A is colder/hotter than thing B”. So long as we end up avoiding or protecting ourselves from whichever things make us cold/hot too fast, the message has worked. When I take a tray from the oven using oven gloves, the side of the gloves touching the tray gets as hot as the tray itself pretty fast - but my hands don’t. The message works. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 7, 2016, 1:52pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/12 "2016-06-07T13:52:13Z")
> [@Les\_Espaces\_Du\_Sommeil](#): > > It makes sense. > > Still, it’s funny how this phenomenon tricks our senses. I would have sworn that the various objects I touched this morning had very different temperatures. Your fingers have two things limiting their temperature rise: 1. They have their own thermal inertia. A small fleck of very hot metal (e.g. a hot chip from a high-speed drill) will feel hot for a split-second before it cools down, and your finger will never get terribly hot because it’s got plenty of mass throughout which to spread that heat. 2. your fingers have their own internal cooling system pulling heat away from the skin. It gets moved down into the deeper tissue by direct thermal conductivity, and by the blood convecting heat away as it flows to/from your skin. When you touch something hot for an extended period, your finger will eventually reach an equilibrium temperature where the cooling rate (from your blood/tissue conductivity) matches the heat input rate from the warm object. That equilibrium temp will be higher for contact with an object of high thermal inertia, which is why metal feels hotter than plastic (i.e. your finger really does get hotter), despite the metal and plastic being at the same temp. If you attach a small thermometer with very low thermal intertia to the surface of a plastic block and another to the surface of a steel block, with both blocks having just come out of the dishwasher, you’ll find that both blocks of material really are at the same temperature, despite what your subjective sense of touch might tell you. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [June 7, 2016, 1:53pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/13 "2016-06-07T13:53:05Z")
> [@Les\_Espaces\_Du\_Sommeil](#): > > It makes sense. > > Still, it’s funny how this phenomenon tricks our senses. I would have sworn that the various objects I touched this morning had very different temperatures. There’s a really nice experiment one can do with this. You have two blocks of identical size in the freezer, take them out and touch them? Block A feels coldest, B barely feels cold to the touch. Okay, which will melt ice faster? You place an ice cube on each of them and it melts seriously fast on the “cold” block to “everyone’s” surprise. Why, because one is made of aluminium and conducts heat to the ice cube a lot faster than the one made of hard foam plastic which is a great insulator. Available, among lots of other places, so just for illustration, here: [Ice Melting Blocks - Thermal Conductivity - Arbor Scientific](http://www.arborsci.com/ice-melting-blocks-thermal-conductivity) ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [June 7, 2016, 1:53pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/14 "2016-06-07T13:53:37Z")
> [@Leo\_Bloom](#): > > High thermal conductivity and low inertia is why copper pans are the bomb–“oh shit the flame is too high…” and lower it: on a copper pan, instant relief; on cast-iron, the pan will stay blasting away for an eternity. I think cast-iron pans are also typically thicker than copper/aluminum pans, i.e. there’s more stored heat just by virtue of there being more stored mass. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [June 7, 2016, 2:22pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/15 "2016-06-07T14:22:12Z")
> [@Les\_Espaces\_Du\_Sommeil](#): > > Thanks for your answers. > > So, in layman’s terms, plastic objects are just as cold/hot as the other items in the fridge/dishwasher, just not as good as the metal/glass ones at transmitting it? Think of it this way: metal feels cold because it sucks the heat out if your body. ---
**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\ **Post date:** [June 7, 2016, 2:55pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/16 "2016-06-07T14:55:14Z")
> [@Machine\_Elf](#): > > That equilibrium temp will be higher for contact with an object of high thermal inertia, which is why metal feels hotter than plastic (i.e. your finger really does get hotter), despite the metal and plastic being at the same temp. While the metal and plastic are _initially_ the same temperature, once they are touched they no longer remain so. The finger almost instantaneously cools down the _contact surface_ of plastic that it touches, and since the plastic is poor conductor, the internal heat of the plastic cannot travel quick enough to balance out the heat being removed by the finger at the surface, so the contact surface of the plastic remains cool to the touch (despite the internal temp of the plastic remaining hot). If the contact surface of the plastic and the metal were _artificially maintained_ at the same temperature, they would both feel hot. ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [June 7, 2016, 3:14pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/17 "2016-06-07T15:14:09Z")
> [@Les\_Espaces\_Du\_Sommeil](#): > > Still, it’s funny how this phenomenon tricks our senses. [Grammar award hijack] Hooray for properly using the singular “phenomenon” instead of the more common but often misused plural “phenomena”! 🙂 [/hijack] ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 7, 2016, 4:30pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/18 "2016-06-07T16:30:26Z")
> [@Machine\_Elf](#): > > … > If you attach a small thermometer with very low thermal intertia to the surface of a plastic block and another to the surface of a steel block, with both blocks having just come out of the dishwasher, you’ll find that both blocks of material really are at the same temperature, despite what your subjective sense of touch might tell you. Well, this is also equivalent to the old standby of a volume’s “total” heat versus measurement of its temperature, which is by definition a measure of some level of molecular energy at some level of near-instantaneous time (hedges so chemical physics and quantum guys can lob their grenades): a drop of hot bathwater, at some temperature, on your skin, vs a whole-body dunk in the whole tub of water at the same temperature. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 7, 2016, 4:59pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/19 "2016-06-07T16:59:59Z")
> [@Alessan](#): > > Think of it this way: metal feels cold because it sucks the heat out if your body. This. And hot metal feels hot because it moves heat into your body. By the way, it’s not just the property of the material, but also the size (weight or mass). A spark from a grinder is very hot, and has very high thermal inertia, but very little mass. So it doesn’t have much heat to transfer to your body, and doesn’t feel hot when it lands on your arm. Similarly, if you remove an aluminum foil and an aluminum pot from a freezer, the pot will feel colder, because it can remove much more heat from your hand than an aluminum foil. (The aluminum foil starts removing heat, but very quickly warms up to body temperature, and at that point it can’t remove any more heat from you.) ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [June 7, 2016, 5:08pm UTC](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720/20 "2016-06-07T17:08:46Z")
It’s further complicated by the way that we sense temperature: > [@](#): > > These nerve endings are not the same as those that receive touch and pressure impressions, because the appreciation of differences of temperature is not very delicately developed in the parts where the tactile sensations are most acute. Thus, the cheeks and the eyelids are especially sensitive to changes of temperature, a fact known by people who want a ready gauge of the heat of a body, e. g., a barber approaches the curling tongs to his cheek to measure its temperature before applying it to the hair of his client. > > The middle of the chest is very sensitive to heat, while it is dull in feeling tactile impressions. The hand is far from being the best gauge of temperature, for heat appreciation is not developed in a due proportion to the keenness of its tactile sensibility. The larger the surface exposed to changes of temperature the more accurate the judgment at which we can arrive - the slightest changes being at once recognized when the entire surface of the body is exposed to them. > > The foregoing facts are well known to persons in the habit of testing the temperature of a warm bath without the aid of a thermometer; they do not use the limited surface of a sensitive tactile finger tip, but plunge the entire arm into the water. The elbow, indeed, is the common test used by nurses in ascertaining that the water in which they are about to wash an infant is not too warm for that purpose. > > Read more: [Temperature Sense](http://chestofbooks.com/health/physiology/Manual/Temperature-Sense.html#ixzz4AukhF0T9) [Next page](https://boards.straightdope.com/t/why-does-plastic-feel-less-cold-hot-than-glass-or-metal/756720.md?page=2)