🚀 go-pugleaf

> The waterproof layer in Gore-Tex is flourocarbon, a sheet of PTFE
> mechanically treated so that it contains pores that are larger than a
> water molecule but much smaller than a water droplet.  Surface tension
> prevents liquid water from getting through (though it can still block
> the pores) but water vapour can escape.  A urethane layer is applied to
> one side to repel oily contamination i.e. body oils.  So Gore-Tex is not
> using polyurethane coatings like any other waterproof fabric.
That's what Gore try to preach. However ...

GoreTex I was in fact just the Teflon layer, but it was a disaster in the
field because the sweat and dirt stuffed the surface tension. Massive
returns. So Gore had to come up with something to protect the Teflon layer.
The Bibler 'ToddTex' fabric may be GoreTex I still - I am not certain.

All the current GoreTex fabrics are Goretex II, which still has the Teflon
layer but covers it with a thin layer of PU. The PU stops the sweat, oils,
dirt etc from reaching the Teflon as planned, but the unanticipated
consequance is that the PU layer is now the limiting factor for
breathability. Despite being very thin, it is more of a barrier than the
Teflon. The ONLY advantage that the Teflon layer now gives to the fabric is
the smooth surface it presents, which allows a slightly thinner layer of PU
to be applied compared to what is normally used on a plain fabric. Gore seem
to be a little sensitive on this issue and usually avoid saying what their
special protective layer is made of, often just saying it is oleophobic.

My understanding is that eVent uses a Teflon layer too (the original Gore
patent expired), but they claim to have another way of protecting the
surface from contamination. So eVent is more breathable.

This is all discussed in the FAQ under Rainwear.

> I assume that GoreTex is a typo for Dubbin.  Not chemical damage, no,
> but rendering the membrane useless by coating the outside with wax,
> clogging the pores.
My error! You are right.

> > What Dubbin did do was rot the stitching. That was in the days of cotton
> > stitching though. Doubt it would damage polyester thread.
> I can find no evidence to support this, and I think it's an old wives
> tale.  I used dubbin on my first set of boots, and never saw any
> evidence of the stitching being affected.
You may be right with the 'old bit: it is a long time since cotton thread
was used in boots! Let's say before the '80s?

Cheers
Roger Caffin
www.bushwalking.org.au/FAQ/