In article ,
Bill Grey wrote:

My experience with Goretex lined boots is that the lining lets in water
after a short while. I suspect it tears along the stitching attaching
the sole, but that's just a guess.

The claims often made for Goretex are complete twaddle, and it is
not fully waterproof even when intact. However, the rate at which
water can get through it is very low, so that would account only
for dampness. But the same applies to its breathability (which
fails in very wet or cold conditions), so water inside could be
condensed sweat.

Disagree entirely, My various boots, Berghaus, Meindle and Trail shoes all
of which had Goretex lnings all performed perfectly in wet conditions.

Physics is not mocked. What I said is correct. You may well
believe in Maxwell's demon, but there's no such animal.

Once Goretex gets saturated, the surface tension no longer blocks
water from passing through, and it is no longer waterproof. But,
as I said, the percolation rate through its very small pores is low.

Once Goretex gets covered with water on the outside, saturated in
any other way, or it gets colder than the dewpoint of the water
vapour inside, it ceases to be breathable.


Regards,
Nick Maclaren.

On 22/01/2013 18:03, wrote:

Physics is not mocked. What I said is correct. You may well
believe in Maxwell's demon, but there's no such animal.

Once Goretex gets saturated, the surface tension no longer blocks
water from passing through, and it is no longer waterproof.

Gore have a ridiculous guarantee, "guaranteed to keep you dry". A
classic case of the large print giveth and the small print taketh away,
but in this case the small print points out the foundation to the claim
is a hydrostatic head well in excess of that considered to be
"waterproof" (MOD say 800mm, outdoor industry reckon 1m).

And that is hydrostatic head, which will be maintained whether or not it
is "saturated". XCR has a measured HH in excess of 4m IIRC, so (a) it's
difficult to see how you can apply that in testing without "saturation"
and (b) percolation rate would be zero /or Gore would be sued left,
right and centre over their fraudulent guarantee/.

Once Goretex gets covered with water on the outside, saturated in
any other way, or it gets colder than the dewpoint of the water
vapour inside, it ceases to be breathable.

That certainly does appear to be the case. Same goes for pretty much
any other waterproof/breathable fabric, of course.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

In article ,
Peter Clinch wrote:

Physics is not mocked. What I said is correct. You may well
believe in Maxwell's demon, but there's no such animal.

Once Goretex gets saturated, the surface tension no longer blocks
water from passing through, and it is no longer waterproof.

Gore have a ridiculous guarantee, "guaranteed to keep you dry". A
classic case of the large print giveth and the small print taketh away,
but in this case the small print points out the foundation to the claim
is a hydrostatic head well in excess of that considered to be
"waterproof" (MOD say 800mm, outdoor industry reckon 1m).

And that is hydrostatic head, which will be maintained whether or not it
is "saturated".

Why? What's the physics behind that? Its claims are nonsense (a
water molecule is NOT much larger than a steam molecule), and my
understanding is that the hydrostatic head is due to hydrophic
material.

XCR has a measured HH in excess of 4m IIRC, so (a) it's
difficult to see how you can apply that in testing without "saturation"
and (b) percolation rate would be zero /or Gore would be sued left,
right and centre over their fraudulent guarantee/.

Not really. Holding up a few metres of water on one side is NOT
saturation, and I am not disputing their claims. But once it gets
saturated, then there is liquid water both sides, and the surface
tension effect gives way to percolation.

I have measured this effect for several fabrics, including Goretex,
and it occurs for that as much as anything else. However, I never
managed to get more than a certain amount of dampness through the
Goretex, so all I could be sure of was that the percolation rate
was non-zero (but negligible). What I can't be sure is how much
would get through with the pumping caused by footwear and clothing
movement.

Once Goretex gets covered with water on the outside, saturated in
any other way, or it gets colder than the dewpoint of the water
vapour inside, it ceases to be breathable.

That certainly does appear to be the case. Same goes for pretty much
any other waterproof/breathable fabric, of course.

Obviously - the same physics applies.


Regards,
Nick Maclaren.

wrote in message ...
In article ,
Bill Grey wrote:

My experience with Goretex lined boots is that the lining lets in water
after a short while. I suspect it tears along the stitching attaching
the sole, but that's just a guess.

The claims often made for Goretex are complete twaddle, and it is
not fully waterproof even when intact. However, the rate at which
water can get through it is very low, so that would account only
for dampness. But the same applies to its breathability (which
fails in very wet or cold conditions), so water inside could be
condensed sweat.

Disagree entirely, My various boots, Berghaus, Meindle and Trail shoes all
of which had Goretex lnings all performed perfectly in wet conditions.

Physics is not mocked. What I said is correct. You may well
believe in Maxwell's demon, but there's no such animal.

Once Goretex gets saturated, the surface tension no longer blocks
water from passing through, and it is no longer waterproof. But,
as I said, the percolation rate through its very small pores is low.

Once Goretex gets covered with water on the outside, saturated in
any other way, or it gets colder than the dewpoint of the water
vapour inside, it ceases to be breathable.


Regards,
Nick Maclaren.

You can theorise all you like I can only comment on what I actually
experienced and still do.

Bill

On 20/01/2013 10:47, Dave West wrote:
Want to really waterproof my new leather boots. I have heard that dubbin
will rot leather and can soften it too much, and even ordinary shoe polish
with its 'spirit' content will dry out leather and do it no favours.

I do have a tube of silicon grease would. Would that be a good idea or might
it also damage the leather? Grateful for suggestions.


worth reading this thread, by Nick Brown the guy who formulated Nikwax
.... importantly he advise new product will out perform Liquid Nikwax ...
which would make it very good indeed.


http://www.outdoorsmagic.com/forum/g...ars/27412.html

On 20/01/2013 17:38, Rick Hughes wrote:

As someone else pointed out NIKWAX

When I had new Army boots ... Liquid NIKWAX first, helped them break-in,
they plain Nikwax .......... helps if boots are warm (put them in airing
cupboard or similar) then rub NIKWAK in with the fingers.
Heat and pressure will work it in ....


Just remembered the other product I used for some time on Army boots ...
Mink Oil ..... only ever had it when I could get it is US PX stores.
Seemed to be a great product .. really soaked in.

In article ,
Bill Grey wrote:

You can theorise all you like I can only comment on what I actually
experienced and still do.

As I posted, my statements are also based on measurement, personal
experience and other people's experience. Whether you have been
just lucky, have never stressed Goretex as much as we have, or
simply been unobservant, I can't say.

It works fairly well (I use Goretex boots), but nothing made by
mortals works perfectly.


Regards,
Nick Maclaren.

On 22/01/2013 21:12, wrote:
In article ,
Peter Clinch wrote:

And that is hydrostatic head, which will be maintained whether or not it
is "saturated".

Why? What's the physics behind that?

Bad phrasing on my part. What I'm getting at is that in order to /be/
staurated you need over a 4m water column providing pressure, and that
isn't going to happen to anyone using it in a normal application. In
other words, the hydrostatic head will be maintained precisely because
the pore structure cannot get saturated until you exceed it.
The pore structure won't be saturated however much the face is.

Its claims are nonsense (a
water molecule is NOT much larger than a steam molecule), and my
understanding is that the hydrostatic head is due to hydrophic
material.

It's surface tension, but you can't break the surface tension until you
exceed the hydrostatic head, which you won't do because it's too big.
So it won't leak until you've got a lot more pressure forcing the water
through than will happen in practical application.

Not really. Holding up a few metres of water on one side is NOT
saturation, and I am not disputing their claims. But once it gets
saturated, then there is liquid water both sides, and the surface
tension effect gives way to percolation.

We are in furious agreement. But /how/ it's going to get saturated in
normal use, given the amount of pressure you need to force water in to
the pore structure is what "oh it will leak, albeit slowly" doesn't address

I have measured this effect for several fabrics, including Goretex,
and it occurs for that as much as anything else. However, I never
managed to get more than a certain amount of dampness through the
Goretex, so all I could be sure of was that the percolation rate
was non-zero (but negligible). What I can't be sure is how much
would get through with the pumping caused by footwear and clothing
movement.

Most examples of "leaking" are condensation on the other side, which is
remarakably difficult to get rid of.

If it's easy to measure percolation through goretex then it would fail
the hydrostatic head tests that Gore use as the basis of their guarantee.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

On 22/01/2013 21:12, wrote:
In article ,
Peter Clinch wrote:

Physics is not mocked. What I said is correct. You may well
believe in Maxwell's demon, but there's no such animal.

Once Goretex gets saturated, the surface tension no longer blocks
water from passing through, and it is no longer waterproof.

Gore have a ridiculous guarantee, "guaranteed to keep you dry". A
classic case of the large print giveth and the small print taketh away,
but in this case the small print points out the foundation to the claim
is a hydrostatic head well in excess of that considered to be
"waterproof" (MOD say 800mm, outdoor industry reckon 1m).

And that is hydrostatic head, which will be maintained whether or not it
is "saturated".

Why? What's the physics behind that? Its claims are nonsense (a
water molecule is NOT much larger than a steam molecule), and my
understanding is that the hydrostatic head is due to hydrophic
material.

Individual water molecules are the same as water vapour ones but they
are bonded together by relatively weak intermolecular bonds. The bonds
between the H and O atoms are not symmetric and so the H and O of
different molecules are attracted to each other. You can't get liquid
water molecules through the breathable membrane without putting energy
into it to separate the intermolecular bonds thus creating water vapour.

In real life you will not get water vapour to flow from a cool
environment outside your jacket to a warm one inside it.

The coating on the outer face of breathable fabrics is there to
attempt to prevent the face wetting out and creating a barrier to
water vapour molecules.

The reasons breathable fabrics fail to keep you dry are that they
either leak (at openings or places where the membrane has failed) or
that they are incapable of transmitting the amount of water vapour you
are sweating into them to the outside.
--
Phil Cook

Individual water molecules are the same as water vapour ones but they
are bonded together by relatively weak intermolecular bonds. The bonds
between the H and O atoms are not symmetric and so the H and O of
different molecules are attracted to each other. You can't get liquid
water molecules through the breathable membrane without putting energy
into it to separate the intermolecular bonds thus creating water vapour.

In real life you will not get water vapour to flow from a cool
environment outside your jacket to a warm one inside it.

The coating on the outer face of breathable fabrics is there to attempt
to prevent the face wetting out and creating a barrier to water vapour
molecules.

The reasons breathable fabrics fail to keep you dry are that they either
leak (at openings or places where the membrane has failed) or that they
are incapable of transmitting the amount of water vapour you are
sweating into them to the outside.

Interesting. ISTR waxes cannot form a continuous film but remain a
series of individual molecules. I wonder whether the gaps between the
molecules allow the passage of vapour and, if so, whether consequent
applications would close those gaps.

In article ,
Peter Clinch wrote:
Bad phrasing on my part. What I'm getting at is that in order to /be/
staurated you need over a 4m water column providing pressure, and that
other words, the hydrostatic head will be maintained precisely because
the pore structure cannot get saturated until you exceed it.
The pore structure won't be saturated however much the face is.

Well, maybe. I accept that is true under simple conditions, but
real life isn't that simple. Inter alia, one of the reasons that
Goretex says that its fabrics must be kept clean is that 'dirt'
can act as a flux. Also, rubbing causes transient overpressure
which can cause 'breakthrough' - and, once that has happened and
both sides of the pores are wet, the surface tension effect is
(mostly) lost.

There is also the question of what the overpressure is for pouring
rain being driven by a force 7 gale :-)

Its claims are nonsense (a
water molecule is NOT much larger than a steam molecule), and my
understanding is that the hydrostatic head is due to hydrophic
material.

It's surface tension, but you can't break the surface tension until you
exceed the hydrostatic head, which you won't do because it's too big.
So it won't leak until you've got a lot more pressure forcing the water
through than will happen in practical application.

I am not convinced, though I have been unable to measure any flow.
What I have seen is water on one side, in conjunction with rubbing
and probably dirt cause darkening and a feeling of damp on the
other. This matches with what I know of the physics involved.

Most examples of "leaking" are condensation on the other side, which is
remarakably difficult to get rid of.

That is true. As we both know, perfect waterproofing is a complete
waste of time for UK conditions, for that reason alone.

If it's easy to measure percolation through goretex then it would fail
the hydrostatic head tests that Gore use as the basis of their guarantee.

Not at all. Those tests almost certainly require a maximum level of
leakage, which can be regarded as negligible. That's reasonable, but
NOT the same as claims of perfect waterproofness.


Regards,
Nick Maclaren.

On 23/01/2013 09:59, wrote:
In article ,
Peter Clinch wrote:
Bad phrasing on my part. What I'm getting at is that in order to /be/
staurated you need over a 4m water column providing pressure, and that
other words, the hydrostatic head will be maintained precisely because
the pore structure cannot get saturated until you exceed it.
The pore structure won't be saturated however much the face is.

Well, maybe. I accept that is true under simple conditions, but
real life isn't that simple. Inter alia, one of the reasons that
Goretex says that its fabrics must be kept clean is that 'dirt'
can act as a flux. Also, rubbing causes transient overpressure
which can cause 'breakthrough' - and, once that has happened and
both sides of the pores are wet, the surface tension effect is
(mostly) lost.

"both sides" implies a sheet. I'm not sure but I was under the
impression you have more of a slab, albeit a thin one, so you'd have
more than one layer of pores as a barrier. Though as noted, I'm not
sure how thick (in terms of how many pores have to be negotiated on
average rather than measured distance) the barrier really is.

There is also the question of what the overpressure is for pouring
rain being driven by a force 7 gale :-)

That would be a clear problem with tent flys, that typically have HH
levels far lower than Goretex. I said over 4m for XCR but my mistake,
it's actually over 40m! Tent flys are usually 2-5 m HH.

Most examples of "leaking" are condensation on the other side, which is
remarakably difficult to get rid of.

That is true. As we both know, perfect waterproofing is a complete
waste of time for UK conditions, for that reason alone.

The other elephant in the sitting room is the damn great holes for
heads, arms etc. required to use the garment in normal situations. And
once the water gets in all those miracle wicking under-layers do their
stuff!




If it's easy to measure percolation through goretex then it would fail
the hydrostatic head tests that Gore use as the basis of their guarantee.

Not at all. Those tests almost certainly require a maximum level of
leakage, which can be regarded as negligible. That's reasonable, but
NOT the same as claims of perfect waterproofness.


Regards,
Nick Maclaren.



--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net http://www.dundee.ac.uk/~pjclinch/

On 22/01/2013 22:33, wrote:
In article ,
Bill Grey wrote:

You can theorise all you like I can only comment on what I actually
experienced and still do.

As I posted, my statements are also based on measurement, personal
experience and other people's experience. Whether you have been
just lucky, have never stressed Goretex as much as we have, or
simply been unobservant, I can't say.

It works fairly well (I use Goretex boots), but nothing made by
mortals works perfectly.



I would add, and how to put this delicately, it does depend upon how
sweaty you are.

Goretex boots work well for me, but the clothing is rubbish because I
sweat 'a bit' given the slightest movement. By pure luck I've come by a
Rohan 'barricade' coat that works for me.

Rob

On 23/01/13 13:45, RJH wrote:

I would add, and how to put this delicately, it does depend upon how
sweaty you are.

Goretex boots work well for me, but the clothing is rubbish because I
sweat 'a bit' given the slightest movement. By pure luck I've come by a
Rohan 'barricade' coat that works for me.

Rob


I second that - having had several Goretex jackets and getting damp
underneath from sweat, I found eVent and my Rab Latok now breathes well!

On Wed, 23 Jan 2013 14:19:52 +0000, Gordonbp wrote:

On 23/01/13 13:45, RJH wrote:

I would add, and how to put this delicately, it does depend upon how
sweaty you are.

Goretex boots work well for me, but the clothing is rubbish because I
sweat 'a bit' given the slightest movement. By pure luck I've come by a
Rohan 'barricade' coat that works for me.

Rob


I second that - having had several Goretex jackets and getting damp
underneath from sweat, I found eVent and my Rab Latok now breathes well!

Hadn't heard of these two but I haven't liked Goretex since it first came
out - something to do, IIRC, with it being described as "breathable".
As it happened I had a long break from walking and when I started again
almost all of my kit was inadequate - 30 yo leather boots /and/ my feet had
changed quite a bit.
With some doubts I looked for modern kit and was pointed towards Paramo. I
does seem to work well, unlike the modern Scarpa boots which aren't as good
as my first leather pair from 40 years ago - nut the Scarpa do have Goretex
in!
--
Peter.
The gods will stay away
whilst religions hold sway