DWR & Breathability

DWR does not alter the breathability in any way.
Unless you use a harsh solvent you are unlikely to be able to 'wash out' the DWR anyhow.

Cheers

Thanks for the input Roger.

I was looking at reviews of the Montane Lite-speed wind jacket and saw that Ryan Jordan mentions that one of the things he did to his Lite-speed was purposefully 'wash out' the DWR. What would be the purpose of that then?

Here's the review: http://www.backpackinglight.com/cgi-bin/backpackinglight/reviews/display_reviews.html?forum_thread_id=1850&skip_to_post=32599#32599

Hi Jonathon

I don't know whether the Montane Litespeed uses a silicone or a fluorocarbon DWR, although I would suspect the latter. As to what Ryan achieved by washing it like that, I don't know either. IF the DWR washed off it must have been a really poor quality DWR treatment, which is a bit inconsistent with Montane quality.

Beats me!

Cheers

PS: added in edit. It may be that Ryan used ordinary laundry detergent powder. That would probably leave enough residues on the fabric that the DWR treatment would be inhibited. Don't know either.

Roger,

I found an answer to why Ryan was attempting to wash out the DWR treatment on windjackets. In fact you also commented on the same thread….. but it was almost 3 years ago.

http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=5177

Ryan wrote in 2006:
>I wash out the DWR and try to make the surfaces hydrophilic, so that when
> moisture condenses on (or sweat wicks to) the inside of the fabric, it dissipates
> via capillary action and thus is more rapidly driven off ("breathed") out of the system.

Hum, yeah, well, … I will very cautiously say that I would not do this myself.

But there is a key question here of whether the windshirt is going to be the base layer (in contact with your skin) or whether it will be over something else. The two cases are radically different.

For a base layer you want the fabric to wick the moisture off your skin. That prevents your sweat from blocking the sweat-pores of your skin. A DWR would certainly get in the way here. However, I think I would look for a non-DWR shirt for this case.

But for a wind-blocking layer I would keep the DWR on. The sweat should be coming of your base layer as a vapour, and a good DWR-treated fabric would let the vapour pass straight through. Without a DWR the fabric could wet out and block the vapour.

Cheers