The persistent DCF water weight myth

[cmoulder]

I've recently read a post or two here and there (including many more in years past) about Dyneema Cuben Fiber's wonderful quality of not absorbing water. Often it is strongly implied — or even stated outright — that there is very little, if any, water retained when the tarp is shaken out, which makes it ideal for the LW or UL backpacker.

I was out backpacking the past couple of days, and last night we got quite a bit of rain in our neck of the woods, which provided yet another opportunity to get some real-world data on this very topic. This morning I wiped off my HG 11' hex (.51 DCF) pretty well with a cotton bandanna, wringing it out regularly. I did not want to shake the tarp vigorously lest I rudely disturb some still-slumbering campers, so I took it down and quietly stowed in its stuff sack. However, I did want to wipe it down to help remove a sizable collection of dead bugs, a slug (yuk), leaves, sticks and some other unidentifiable schmutz that didn't appear to be from this planet.

When I got home, I weighed the wiped-but-unshaken tarp, took it out and shook it quite vigorously (6 good shakes), then stuffed it back in the sack and weighed it again.

Bone dry, the tarp, guy lines (total 50' of 2mm Glowire) and stuff sack weigh 194.2g (6.85oz).

Wiped and stuffed, the weight was 414.7g (14.63oz)

Wiped and shaken, the weight was 385.3g (13.59oz)

Therefore, the wiped and shaken tarp still weighed 191.1g (6.74oz)(almost double!!) more than the dry tarp. Yes, I am acutely aware that this weight includes water absorbed by the guy lines, but this is a far more realistic number because we all carry guy lines and they will also always get wet if the tarp does.

So the assumption that DCF gains little, if any, water weight is clearly incorrect. By a LOT!

[TrailSlug]

That wet weight is still lighter than most other dry tarps of similar size so if one wants a lightweight tarp this is still the tarp that sets the standards. If you want to do a comparison test get a similar sized silNylon tarp and do the same test. Water will always add to the weight of any item. Just some more than others. Thanks for the info.

[TallPaul]

Good stuff.

Is this another way to look at it?

Assuming the DCF tarp retains water at the same rate as a Silpoly or SilNylon (for example doubling the dry weight)... doubling the weight a lighter tarp still beats doubling a heavier tarp.

DRY WEIGHT:
13.32 oz Silpoly The Quest
5.14 oz DCF Hex

8.18 oz Dry weight savings

WET WEIGHT (assuming 50% increase)
26.64 oz Silpoly The Quest
10.28 oz DCF Hex 10.28

16.36 oz Wet weight savings

Edit: Guess I should add the % water retention may vary by material, but the basic premise would still apply.

[Yarome]

...there is very little, if any, water retained when the tarp is shaken out...

From that, I didn't take away that the OP was making a comparison against other popular tarp materials, simply a real world test of the water retention claims for DCF.

On a multiple day hike, it seems pretty pertinent info if your considering material to size to weight to cash outlay. I'm still just getting my feet wet, but from a limited noob perspective it seems like DCF is used a lot to be able to pack "bigger" rainfly's with minimal weight increase over other materials rather than a direct UL replacement for a similarly sized rainfly in a heavier material.

If that's true, then comparing them becomes a bit more difficult if you're looking at an 13x10 DCF with doors taking on more than double the water weight vs. the 11x8 hex silnylon it's replacing.

[TrailSlug]

I guess I've missed the fact that DCF doesn't get heavier when wet. In my investigations of Cuben Fiber I've only found that it's lighter and waterproof and the most important aspect has been the fact that it's lighter. Wet or dry this is still a true claim as is it's a ton more expensive.

[Yarome]

Wet or dry this is still a true claim as is it's a ton more expensive.

That seems to be the universal truth.

I've looked at DCF quite a bit, but gearing up a full initial setup in a relatively short period of time... it's too far out of my price range for awhile. When I bought my hammock no one told me, "oh buddy... your wallets in for it NOW!"

[cmoulder]

No doubt DCF remains the weight champ. And I've got quite a few yards of it in various tarps, tents, packs and stuff sacks.

My one and only goal is to refute the claims that, when shaken out, that "most" or "almost all" (I've read at various times on various forums) of the water is gone. It simply isn't, and it's easy enough to quantify yourself if you have a decent scale.

One thing I have never tested is drying time, but my impression — and somebody might be able to correct me on this — is that DCF does indeed dry out quicker in identical conditions compared to silpoly or silnylon.

[MikekiM]

I just did the same thing.. figured since cmoulder and I were out in the same rain, it would eliminate at least one variable.

I weighed the HG 12' DCF Standard with doors, four ZPacks Z-Line ground lines with Tarp Worms and split Zing-it ridge lines.. no hardware. All was stowed in HG mesh snake skins, and then in a DIY DCF stuff sack... I first shook it and then wiped it down with a microfiber cloth before stowing it.

I weighed it immediately upon arriving home from this weekends trip.. it weighed 17.53 oz / 498 g

Put it outside for a good few hours in the sun and just put it away... it weighed 9.88 oz / 281 g

Make of this what you will....

[Yarome]

Make of this what you will....

You mean... your scale is for crap? You only used it twice over a couple hours and the readings were all over the place. Shoulda bought it from Amazon. 30 day no-hassle return policy, y'know.

[SilvrSurfr]

Weighing the wet guy lines doesn't sound particularly wise. That tells us nothing about whether it's the guy lines absorbing the water or the DCF tarp itself.

Nevertheless, it's reassuring to see that a DCF tarp will ALWAYS weigh less than silpoly or silnylon, wet or not.