Re: [Paddlewise] Ideal Touring Paddle Jacket

Dave Kruger wrote:

> ...  Whatever its name, each depends on having
> submicroscopic holes in a water-repelling layer (coating, membrane,
> you
> pick the label) which water vapor molecules can diffuse through, but
> which
> water **droplets** -- being larger -- cannot wick through. ...

Well said.

I have owned various Gore-Tex garments as well as various garments with
microporous coatings.  It has been my experience that  the Gore-Tex is
more breathable (for a given degree of waterproofness).  I have a theory
as to why this is the case.  As Dave states above, you need the holes to
be small enough so that water droplets cannot pass through. But due to
inherent imperfections in the manufacturing process, there is
significant variability in the diameter of the holes.  It is the
*larger* of the holes that must be smaller than the water droplets.
Given this, and given sufficient dispersion in the distribution of hole
sizes, some of the smaller holes may be too small to allow water vapor
to pass through.  This is where the differences arise.  I would assert
that it is harder to achieve uniform hole size when applying a
microporous coating (in comparison with the manufacturing of the
Gore-Tex membrane), and thus the microporous coatings have a higher
variance in pore size.  This implies a higher percentage of excessively
small holes in the case of the microporous coatings, which would result
in less breathability than with Gore-Tex.

I hasten to add that this is just my own theory.  But it would help to
explain why the microporous coatings are either less breathable or--as
in the case of Ultrex--both less breathable and less waterproof than
Gore-Tex.  Increasing the size of the smaller holes to improve
breathability would increase the percentage of larger holes that allow
water droplet penetration.

So that's my crazy theory--the superior performance of Gore-Tex is due
to greater uniformity of hole sizes in the manufacturing process.

Dan Hagen


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