I have got a plastic bin, about 20 litres capacity, with a tight-fitting but not airtight lid, that I park in a cupboard I rent in the building where I also work. I use that to collect sweaty clothes and damp towels that I am stuck with after working out before coming to work. The container and its contents are stored at room temperature.
About once a week I swap out the container to put the contents into my laundry pile.
What’s curious: At that time the container is definitely slightly warm to the touch i.e. above room temperature. (it has also water condensation on the underside of the lid but that’s not unusual in the circumstances.)
So: a plastic container with 3-4 sets of sweat-soaked underwear and the same number of damp towels, left for a few days (i.e. no residual body heat in the clothes), with no unusual smell of the contents (so fermentation is probably out) - and its surface is slightly above room temperature.
WAG: Maybe the body oils in the wet sweaty clothes are undergoing oxidation? This is the same process that can produce spontaneous ignition in, say, oily rags left in a heap:
If this is correct, the reason you’re not getting regular closet fires from your sweaty clothes is because the amount of combustible oils in them is so small. But there’s enough so that the oxidation generates detectable heat.
Note that IANAChemist and the above rationale is strictly an argumentum ab ano (i.e., pulled out of, um, thin air).
In any case, I suspect it’s simpler than that. Touch (and, in fact, any human sense) is woefully inadequate at detecting absolute levels. Photographers use light meters because their eyes cannot reliably gauge the amount of light they are seeing just as meteorologists rely on thermometers to measure temperature because their skin can’t repeatably tell exactly how hot or cold it is. While I don’t care to posit a mechanism here, it’s likely that something about a tub full of damp textiles either reflects more radiant energy back to your hand or lowers the heat transfer rate from your hand to the plastic surface (this latter effect is why at the same ambient temperature a piece of metal will generally feel cooler than a piece of, say, wood.)
If it’s a real and measurable & a not a psychological phenomena (as mentioned) if you try hard enough you’ll find some source of light or vent that is delivering energy to the bin. Why not just drop a cheap key ring thermometer in the bin and when you pull out the clothes take a look at the reading to verify the temperature increase. that will tell you if it’s simply a perceived increase or verifiably true.
Oh, I’m not talking about psychological issues, I’m talking about real, physical effects which cause your sense of touch to feel something as warmer or colder because it IS affecting your skin temp by one of the proposed mechanisms and the inability of senses to make accurate measurements, which is neurological rather than psychological.
In any case, a cheap infrared thermometer (I’ve seen them as cheap as $15 or so) is probably better, since he wants to measure the surface temperature of the container, the part that’s he’s actually touching. Plus, it takes readings faster.
But there is the perfectly usual smell of sweaty clothes? Sweat doesn’t smell; the bacteria living on your skin (and on your clothes and in the air …) is what smells. That could just be the heat given off by thriving colonies of various bacteria.
No, that’s unpleasant to think of; there is a heating pipe behind the wall or under the floor.
Plastic is a decent insulator, and touching anything plastic that is room temperature is probably going to feel warmer than room temperature. Sucks less heat out of your finger.
I bet the container would feel a lot colder if it were aluminum, even if it were the same temperature.
I’d also guess that there’s not a big difference, and it’s probably either than the whole cupboard is actually warmer than the rest of the building (like maybe an uninsulated heat pipe runs through the wall just behind it), or it’s just the plastic feeling warmer to the touch than the OP’s metal desk.
But theoretically, if there’s lots of condensation on the lid, it will be warmed slightly by the condensing vapor (though not very much and it would quickly fall back to ambient temperature).
Not at all. But you and I are not the only two people reading this. I should have made it clear that I was just pointing out the terminology to those that weren’t familiar.
