Condensation in “issue” Gore tex bivvy. Genuine Gore tex?

[John Elstob]

This question may have been asked in the past so apologies if that is the case.
For the people who have experience using bivvy bag!

I purchased an allegedly un-issued Gore-Tex Bivvy bag (the type currently issued). The first time I used it, my sleeping bag was slightly damp the following morning and there was a little bit of condensation on the inside of the bag.

A month or so ago I bought general-purpose NATO Gore-Tex. This is a central zip Bivvi but this one has no hood. The first time I used it I had no moisture inside my bag nor was my sleeping bag damp on the surface.

I started to wonder if the first bivvy I bought was an actual real Gore-Tex Bivvy bag or had I been caught out by someone selling dodgy gear. How can you tell if it’s genuine? And has anyone else experienced a slightly damp sleeping bag using current issue bivvy bag?

 

[MrEd]

Are you sleeping with your head inside or outside?

 

[John Fenna]

And what were the environmental conditions? Frost? high humidity? rain on the outside of the bivvi? dry desert air?
I no longer use Gore Tex - it fails to excel in so many conditions, only really working when it does not need to work....

 

[TLM]

I no longer use Gore Tex - it fails to excel in so many conditions, only really working when it does not need to work....

Can't but agree there.

The basic condition for any of the mesh films is that dew point is outside the membrane, that often means that it cannot be very cold. If it is dry on the outside it helps a lot. Yes in those conditions one does not really need any extra help in keeping fairly dry.

 

[John Elstob]

Are you sleeping with your head inside or outside?

Sleeping with head outside the bivvy

 

[Great egret]

I no longer use Gore Tex - it fails to excel in so many conditions, only really working when it does not need to work....

Same here...

 

[The Lord Poncho]

Over the years I must have slept many hundreds of nights in issue bivi bags, and i've only ever found a little bit of dampness to accumulate around the foot end. Whilst not being able to be advertised as such, i do suspect that most issue 'goretex' is in fact the real thing. In contrast i have a very expensive hooped bivi bag useing the special 'super breathable ' goretex, that suffers horrendously from condensation, even with it zipped open as much as i can/dare. As mentioned above, it all depends on their being a sufficient gradient of heat/humidity from the inside to the outside of the fabric.