Sasha,

After reading and rereading your latest posts a time or two there is nothing
left but to take a bunch of teapots, do the pour thing, and observe. Let's
just see. Of course, I'd never thought of the drip patterns quite the way
you describe them, but it sure does make a lot of sense.

Michael


Alex y.com4/13/05


>
> "Lewis Perin" > wrote in message
> news
>> "Alex Chaihorsky" > writes:
>
>>
>> - the pot drips if a drop can form where tea liquor and spout meet;
>>
>> - the surface tension needed for drop formation is increased by a
>> relatively fluffy spout lining like a glaze, while a dense material
>> like unglazed ceramics attracts the liquid, preventing drop
>> formation.
>
> Approximately
>
>>
>> In the naive and sloppy part of my mind where I've accounted for this
>> kind of thing until now, I assumed that vitreous surfaces repelled
>> water because they were dense.
>
> Let me put it this way - a drop of liquid has to "decide" if it rather be
> attracted to contact material (and then it wets it) or to itself (and then
> it forms some sort of spherical surface. The density of the immediate thin
> film on the contact surface is critical for such decision.If the desnity of
> such is higher than the liquid's it is likely to wet it and form the
> negatively curved surface. If it is lower - it will likely to form
> positively curved surface. A good example is ater and mercury in a glass
> tube.
> The more sperical is that positively curved surface, the taller is the drop,
> the more distance between the surface and the center of the drop's gravity
> and the more likely it will lose contact with the surface and actually drip.
> the bettr it wets the surface the thinner is the liquid film and the less
> likely it would lose contact with the surface and drip.
>
>> But really, at the level where this
>> stuff takes place, I suppose it's a long way between particles, so
>> there had to be something else in play, right?
>>
>> /Lew
>> ---
>
> Not that I am aware of.
> I have not looked at any math models recently, but if I remember right
> gravitational pull plays major role in this. In some special cases like with
> oils ionic forces are also at play.
> One could have suspected also some additional molecular forces at play,
> especially in water, bust since all liquids are subject to this type of
> effect disregarding the chemistry its unlikely that such forces play any
> significant role in common cases.
>
> Sasha.
>
>