Money on my face!

[Bubba]

this question was recently posed to me:

 

"If i take a coin (or bottle top, paper clip etc.) and press it hard to my cheek/forehead then when i take my hand away the coin sticks to my face for a bit before falling off. why?"

 

i suspect this is a chemistry question (Van Der Vaals forces???) but i really have no idea. Can anyone else give a good explaination for this phenomenon?

 

ps. theres no need to make jokes about washing, it still works after you'v just washed.

[coquina]

this question was recently posed to me:

 

"If i take a coin (or bottle top' date=' paper clip etc.) and press it hard to my cheek/forehead then when i take my hand away the coin sticks to my face for a bit before falling off. why?"

 

i suspect this is a chemistry question (Van Der Vaals forces???) but i really have no idea. Can anyone else give a good explaination for this phenomenon?

 

ps. theres no need to make jokes about washing, it still works after you'v just washed. [/quote']

 

I don't know that this is true for sure, but I think what happens is that when you press hard you displace the blood out of the vessels and the fluid out of your tissues, when you remove the pressure, the fluid tries to fill back in and "squeezes" the coin in place.

[YT2095]

your pores when magnified a few times have a similar shape as a suction cup has, naturaly being on the face the hairs are also alot finer and fewer, so basicly in the area of the coin or bottle cap you`re setting up a hundred or so tiny little suction cups, no one is strong enough alone to hold the item in place, but in tandem, the combined effect will be

 

with regards to washing, I`de esstimate that a dry but dirty face will have less "suction" as some of these pores will already be blocked, a Clean face should work the best, a fine layer of sabacious oil(sp?) should also improve it too, hence it`s always better to lick a rubber sucker before attatching it to metal or glass.

 

edit: and although you say you don`t like "Opinion" in Science, the above is entirely MY opinion, wrought of personal Reasoning skills and Logic

[Phi for All]

As YT mentioned, sebum from hair follicles on the face is made up of cholesterol, waxes, parrafin and triglycerides that provide a surface tension to the skin, making it waterproof and also adding to the "sticking" effect. Even after washing, the sebaceous glands keep this coating on your skin to maintain surface tension, keeping the skin impervious to bacteria, most gasses and chemicals, and flat metal objects placed against it.

[Bubba]

Thank you all for you helpful replies. YT2095 that seems like a very reasonable hypothesis and I can see no immediate problem with it.

 

Notice I said 'hypothesis' and not 'opinion'. It's a hypothesis because you'v used facts we know about (pore shape, sebaceous oil) to explain an observed event (the sticking coin), hence showing an excellent scientific process. Now we just need to do some experiments, test different pore size and shape against different currencies and we could publish a paper. Had you simply said “the pores on your face act as suction caps” then no self respecting journal would publish us.

[YT2095]

One endevours to do ones best

 

as for experimental proceedures, I think I`de try using a uniform surface as a standard, say a bottle cap, and then find a way to add weight to is and time it.

then shave your forhead and try that, then wash and apply an anti-perspirant and try that, talc powder should be interesting too, as that will block the pores and Should fail.

 

these, and many many more ideas coming soon to a cinema near you!