Path: utzoo!attcan!uunet!ginosko!husc6!ogccse!blake!uw-beaver!ubc-cs!van-bc!rsoft!mindlink!a309
From: a309@mindlink.UUCP (George Lin)
Newsgroups: comp.sys.amiga
Subject: Seagate (we're getting out of hand)
Message-ID: <422@mindlink.UUCP>
Date: 29 Jul 89 17:07:35 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 48

> Org.  : University of Massachusetts, Amherst > Person: Paul Swanson

> Surface tension forces should take care of spreading it out on a
> molecular scale.

Well, you are right, and you are wrong.  Surface tension will help to
spread out a material, but it also helps to hold a material in a ball. And the
key word here is SURFACE.  If you are talking about capillary
action (ie, a matrix such as paper or cloth, both will permit a fluid
to have a SA/V ratio) then the surface tension will help to spread out
the lubricant very rapidly.  But if you are referring to a drop of oil
on a sheet of glass, then the drop of oil will remain a drop of oil
(provided the drop is small enough and its mass is does not overcome the
surface tension.  At 5 molecules thick, well, that's pretty small).
TRY IT!.

> Actually I am willing to bet that the lubricant molecules are quite
> large although not as large as DNA molecules.

Well, I'm willing to bet that the lubricant molecules are not even 1/100
the size of a DNA molecule.

> However, the calculation of the layers of molecules was probably done
> macroscopically.  Take the  total number of molecules put down on the
> surface.  Determine the "size" of a single molecule.

In this case, Absolutely not!  How are you going to know how many
molecules you have applied to the surface of the disc?  The lubricant
with a linin cloth, remember!?  How much lubricant is left
on the cloth?  How much on the disc?  You can get a rough approximation
if you are dealing with a large quantity of lubricant, but in this case,
we are not.  5 molecules thick on a 5&1/4in disc is less than a drop.
I submit to you, the only way find the thickness of the lubricant layer,
is measurement.

> The surface is no doubt very much like a mountain range and the
> lubricant will tend to fill in the valleys ...

Well I agree with you totally.  And this is what I was trying to say.
By this reasoning, the average thickness would be much, much more than
a few molecules thick.

> The Bonding at the interface of two materials is the only thing that
> determines how well they will stick together not the thickness of
> them.

Yes, that makes sense (after all the valleys have been filled in, of
course).