Subscribe Contribute Advertise Facebook Twitter Instagram Forums Newsletter
waterproof backpack fabric
Display Avatars Sort By:
Brendan Swihart
(brendans) - MLife

Locale: Fruita CO
Re: waterproof backpack fabric on 06/03/2012 15:00:59 MDT Print View

Something to consider re pack fabric weights: Most UL style packs only use around a square yard of fabric, so the weight savings of using something like VX21 vs cuben is only a few ounces and the improvement in durability is huge. Where you can really save weight is on webbing, buckles, 3d mesh, etc. I've made packs out of everything from cuben to DX40 and have decided that the lighter stuff isn't really worth the minimal weight savings (after a big hole in a cuben pack from minimal abrasion the first day I used it).

On the other hand, once you make your first pack you'll be hooked and be immediately planning your next one so maybe durability isn't a big deal at this point ;)

Steve C
(smit)

Locale: sierra nevada
taping WX vs TX vs VX on 06/03/2012 15:26:57 MDT Print View

You mentioned waterproofness as a goal and there has been some talk about taping seams. The WX and TX line of fabrics have the PET as one of the faces. VX has 50d for one of the faces and the PET sandwiched so I can see how you would tape it. When using the TX line how does the PET face wear as a pack exterior? (Assuming you have taped interior seams) Or do you have to apply a seam sealer on the seams from the outside and have the PET face on the inside of the pack?
As an aside...I find the "lt gray" TX07 to be more like off white.

-Steve

Brendan Swihart
(brendans) - MLife

Locale: Fruita CO
Re: taping WX vs TX vs VX on 06/03/2012 16:08:11 MDT Print View

I've done some tape testing on the mentioned fabrics. The McNett iron on tape adheres very well to the VX taffeta back and fairly well to the TX/WX back. I've also made tape using 3M 9485 and a lightweight urethane backed taffeta or cuben. Works great with all of the above fabrics. None of the tapes adhere very well to the face fabric, probably due to the DWR.

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: Re: taping WX vs TX vs VX on 06/03/2012 16:16:52 MDT Print View

3M9485 tape onto the coated face of 70 gsm PU-coated nylon fabric, onto the tricot knit face of the X-Pac on the inside. Rub down hard and leave for a day.

Have to avoid friction from gear which can peel up the end of the fabric 'tape', so some thought over the layout of the taping is good. Problem is mainly at the top of the bag: ends at the bottom just get 'sat on'.

No, 3M9485 will not adhere very well to the DWR-coated face fabric on X-Pac, quite right. Not much else will either (PU, silicone ...)

Cheers

Steve C
(smit)

Locale: sierra nevada
x-pac taping on 06/03/2012 17:02:18 MDT Print View

Brendan,
Not sure I am following you, did you use two sided tape and cover the seam then cover the tape with a strip of fabric?

Brendan Swihart
(brendans) - MLife

Locale: Fruita CO
Re: x-pac taping on 06/03/2012 17:39:39 MDT Print View

No, put the tape onto the fabric (PU coated side), then cut the strips of fabric so now you have essentially a one sided tape. Peel off the backing and tape the seams.

edit: for this application I've used the lightest black PU coated taffeta from OWFINC

Edited by brendans on 06/03/2012 17:41:20 MDT.

Steve C
(smit)

Locale: sierra nevada
tape on 06/03/2012 20:06:07 MDT Print View

I think I get it now, you do use 2 sided tape but the sequence you follow of "making" tape then applying it makes more sense then what I proposed. Thanks for the great tip!

Roger Caffin
(rcaffin) - BPL Staff - MLife

Locale: Wollemi & Kosciusko NPs, Europe
Re: tape on 06/04/2012 01:20:04 MDT Print View

> you do use 2 sided tape
Actually, not quite.
3M9485 tape consists of a single layer of adhesive. No carrier film at all. It's called a 'transfer tape' becasue you transfer the adhesive to your own carrier - the fabric.

Cheers

Samuel C. Farrington
(scfhome) - M

Locale: Chocorua NH, USA
WP pack material on 06/06/2012 14:23:36 MDT Print View

Hi Jennifer,

I was not going to respond to your OP until you later added that,
"The pack only needs to be waterproof against rain, storm, snow etc... no full submersion ..."

Given that you are not looking for a drysack-type piece of gear such as those used on (and in, if the boat flips) the water, please note (oz. are ounces per square yard):

Rockywoods has a 3.8 oz. 200 denier coated ripstop nylon in a sand color and intended for military use that might work for you:
http://www.rockywoods.com/Fabrics-Kits/All-Ripstop-Nylon-Fabrics/210-Denier-Doublewall-Ripstop

McHale Packs has a dark gray 4.4 oz 210 denier coated riptsop nylon with a diamond Dyneema grid: http://www.mchalepacks.com/ultralight/detail/fabric_colors.htm
It is not listed for sale on the site, but Dan was willing to sell me a couple yards.
The coating is of recent vintage, and much better IMO than coatings on other spectra and Dyneema gridstops I have purchased before.

I've ordered and looked at both of the above, and they are both very waterproof; but without an HH tester, I could not tell you which is more WP. Dan may also have some 3.5 oz gridstop, but I don't know if that has the newer coating.

Quest Outfitters had some double-coated material in the 3-4 oz. range also, but ran out of it and the site states there is no expectation of more.

I was going to use somewhat heavier 4.9 oz. Xpac VX07, but once I got sewing with it, became concerned with the stretching of the material at the stitch holes, much the same issue as with the mylar film in Cuben. It also began to wrinkle and pucker into odd shapes when tensioned as part of a backpanel, and looked dreadful at one point where I had to remove some stitching. A recent post on this site showing delamination of some lighter Xpac added to my concern. There is a heavier VX21 Xpac which runs over 6 oz.; but I felt mission creep was beginning to occur, and drew the line.

I also looked at 2 varieties (Warmlite and Seattle Fabrics) of medium green sil-coated 1.9 oz. ripstop nylon that weighed about 2.5 oz with the coating, but they were not as waterproof as any of the above mentioned materials. The 1.9 oz nylon is around 70 denier, also; so is not as strong and durable as the 200-210 denier material. I will use it only for pockets inside the pack. Have used the Warmlite for several years for stuff bags, and it holds up very well.

So I will use the sand Rockywoods material for most of the pack, probably with some of the gray Dyneems grid material from Dan McHale for a bathtub pack bottom with a light coated liner inside it. Am OK with 1.4 oz. Thru-Hiker silnylon even for tent floors, but want something tougher for a pack, as they can get a lot of abuse. Since the T-H silnylon has a very high HH and weighs under 1.4 oz., I will probably use it to line the pack bottom, and probably coat one side of it with a very thin coating of GE sil-glue so it doesn't bunch.

Rockywoods also has some heat-sealable coated nylons in the same weight range that might be of interest for making waterproof seams. I'm content to use the Seamgrip for seam sealing - have found it very reliable.

Hope this is helpful.

Edited by scfhome on 06/06/2012 14:27:08 MDT.