Why Does Water Soak Through Mugs?

[sophiecentaur]

Your explanation bothers me because of the amount of water involved. I'm sure it needs another source, in order to produce visible condensation from such a small volume of air / waterproof surfaces.

Also, the outer rim would be cooler - not hotter. The top of the 'arch' underneath would be the hottest because it is furthest from the outside and right next to the hottest bits of coffee down there.
I will try it myself - with best porcelain and with cheap pot mugs.
How sad am I?

 

[tuilli]

..initially condensation occurs over the entire surface

of the table

underneath the mug...

 

[sophiecentaur]

I see what you mean now but still - how much water are you expecting to exist in that small volume of air?
You could prove it was possible by a calculation, if you wanted to.
And, in any case, unless the bottom of the mug was wet, there would be no more water (liquid or vapour) under it than when it was cold (immediately before the hot mug was placed there).

 

[JaredJames]

You could prove it was possible by a calculation, if you wanted to.

If anyone does choose to indulge us, we'll be wanting it in imperial.

 

[sophiecentaur]

Would you be wanting the answer in drams, gills, fluid oz or teaspoonfuls?

 

[JaredJames]

Preferably in Board Feet.

 

[DaveC426913]

per fortnight.

 

[Phrak]

Thank you all for a very entertaining thread. And if I may be so bold, I nominate sophiecentaur for Kitchen Scientist Extraordinaire, Plenipotentiary to the Queen.

In an indirect approach, does the exposed terracotta of a desicated mug evolve gas when heated in the expected time span? There must be some easy way to explore this. The best I can think of is to invert one in a deep bowl of water and nuke it.--maybe sink a few test mugs in a crock pot, bottoms up. That might do it. Tiny little bubbles of air on the bottom rims could tell us something if they appear.

 

[Molydood]

Tuilli, nice try but I still don't buy the condensing bubble of air theory I'm afraid - and I think you know it :-) I would expect a solid circle of liquid as opposed to a ring IF there was sufficient water content / humidity in the bubble under the cup.

 

[Molydood]

Phrak, I now have TWO things to do on Monday :-)

 

[JaredJames]

per fortnight.

And if I may be so bold, I nominate sophiecentaur for Kitchen Scientist Extraordinaire, Plenipotentiary to the Queen.

Seconded!

 

[tuilli]

Tuilli, nice try but I still don't buy the condensing bubble of air theory I'm afraid - and I think you know it :-) I would expect a solid circle of liquid as opposed to a ring IF there was sufficient water content / humidity in the bubble under the cup.

Ha I love it, drinking tea has become so much more complicated :b Still clinging on to the hot air bubble theory. Just to clarify, the air bubble will have the highest temp towards the centre, thus the part of the table directly under the centre of the mug will heat up most over time. Therefore condensation is more likely to occur towards the colder edge.
True, the air could not possibly hold enough water to form any noticable condensation. So, provided there is some source of water either on the mug or the table, the air will continually absorb moisture from that source until saturated, but the vapour also continually condenses on the table. So the volume of air doesn't determine the amount of water that ends up on the table. Rather, the air just acts as a sort of bridge to get the water from the mug pores or whatever on to the table... Haha the whole thing is ridiculous but can't get it out of my head

 

[JaredJames]

Ha I love it, drinking tea has become so much more complicated :b Still clinging on to the hot air bubble theory. Just to clarify, the air bubble will have the highest temp towards the centre, thus the part of the table directly under the centre of the mug will heat up most over time. Therefore condensation is more likely to occur towards the colder edge.

The mug will conduct heat far better than the surrounding air. The ring section at the bottom of the mug which contacts the surface will be hot. The coldest area initially will be the air at the centre where you claim it will be hottest. It's actually the inverse of what you are claiming.

 

[Phrak]

Phrak, I now have TWO things to do on Monday :-)

Me thinks the wife will be out of the house as coffee mugs go unguarded.

 

[Molydood]

I have performed the experiment again, this time being ultra careful not to spill a single drop of water anywhere, and also ensure that the exterior of the cup is completely free from any moisture. I have also tried using Sophie's suggested technique of saturating the porous base of the cup with cold water after the cup is already hot. I could not try Phrak's suggestion as I cannot see through the microwave door… a shame because the 'SPCM - society for prevention of cruelty to mugs' is currently not around to offer 'advice' which is a good opportunity for mug testing

FIRST experiment - dessicated cup trial
-cup hasn't been used for a few days so probably 'dry'
-I filled the cup with boiling water, wiped all exterior surfaces with a paper towel and let stand for 2 minutes
-no liquid rings appeared

SECOND experiment - saturated cup trial
-I heated up the mug by standing boiling water in it for 2 minutes
-I then inverted it and held under running cold water so that the concave base was being filled constantly with cold water… I did this for about 1 minute and then dried cup with paper towel
-I then filled cup with hot water, wiped all exterior surfaces with a paper towel again and let stand for 2 minutes
-no liquid rings

THIRD experiment
-I first wiped all exterior surfaces of the cup with paper towel and then I carefully placed a single drip of water on the rim of the cup (not the base, but the bit where you would drink from at the top) and then placed the cup on a table
-a liquid ring has appeared

CONCLUSION
a single droplet of water finding its way down the side of a cup can generate a full 360 degree liquid ring at base of cup - I believe this proves that I am an idiot who did not perform the original experiment very well - but I cannot say this for sure because I am not actually capable of performing experiments as I have just proved. I think that is a bit of a paradox - similar to saying "don’t believe anything I say because everything I say is a lie". I understand that paradoxes are (vaguely) scientific so apologies for going off topic ;-)

 

[sophiecentaur]

What an excellent piece of experimental work. Well done. Now you must send the documentation to Physics Review and get them to publish. You are clearly on your way to academic stardom. And it's not even near the beginning of April yet.

 

[Phrak]

THIRD experiment
-I first wiped all exterior surfaces of the cup with paper towel and then I carefully placed a single drip of water on the rim of the cup (not the base, but the bit where you would drink from at the top) and then placed the cup on a table
-a liquid ring has appeared

Clever. I wouldn't have considered that experiment. Yet it still leaves me wondering how much water the porcelain can evolve in extreme use. Do you have a pressure cooker?

And why aren't there any kitchen gadgets like autoclaves, centrifuges, or bell jar? There could be opportunity in providing these useful food preparation devices.

 

[Molydood]

Great idea; the centrifuge could be used for making mashed potato or tomato puree.
Bell jar could be useful for storing open bottles of wine to prevent oxidation
and who needs a dishwasher when they have an autoclave?