put, the paper machine intermeshes tiny fibres
of cellulose together in the wet state. This
is pressed and dried, and gets compacted into
the form of paper as we know it. When seen under
a microscope, the mesh of fibres is clearly
seen, with individual fibres exhibiting their
familiar long, tubular, well-defined shape.
These fibres lie loosely interspersed and intertwined,
with spaces in between them. These spaces readily
allow water, oils and gasses to pass through
the paper. The tighter the fibres are packed
together, the more impenetrable the paper becomes.