"you" wrote in message
...
In article ,
"Barry" wrote:
Trying to measure the thickness of a single sheet of paper with a
ruler
graduated in eighth's of an inch is analogous. About all you can say
with certainty is that the paper is much thinner than 1/8 inch.

Well not exactly, IF, one were to take a "Stack" of said paper, that
was
exactly 1/8 of an Inch thick, then count the number of sheets, and
divide the 1/8 inch by the number of sheets, One could get a VERY close
approximation of the thickness of a single sheet...... Duh...

Note that I said the thickness of a _single_ sheet. Your method would
give an approximation of the average thickness of the sheets used to make
up the stack. But if you have ever worked with a Fourdriner machine that
is not controlled well, i.e. the thickness varies with time due to any
number of variables, you would need to know the thickness of a number of
individual sheets to determine which variable is causing problems.
Typical variables that would cause the thickness of a sheet to vary
include, but are not limited to, head box level, "wire" speed, pulp
"consistency", felt pressure, calendar pressure, the type of wood used,
the lignin removal process (Kraft, caustic, or solvent), Crown Control
pressure, drying roll steam pressure, and at least a dozen more. For
example, sloshing or waves in the head box would cause thickness
variations in both the machine and cross direction, while "wire" speed
would only cause thickness variations in the machine direction. So there
are real reasons for measuring the thickness of a single sheet.