DCF prices going up!

[Henry Shires / Tarptent]

> https://www.dsm.com/dyneema/en_GB/sustainability/bio-based-dyneema-fiber.html

> Made from waste from timber pulp.

Fiber yes, Mylar no.  As a mass percentage of the actual finished material, at least for the tent fabrics, the Dyneema fiber component is very small.  When you read the DSM literature it references a “tonne of bio-based Dyneema.”  That’s about 2,200 lbs of fiber and equivalent to many hundreds of thousands of yards/meters of DCF material.   Be skeptical of marketing hype ..

-H

[Michael B]

Well, I’d not bring overseas into this conversation as there is little to no domestic source of any waterproof canopy material – DCF actually seems it’s be one of the few. Almost all, if not all, sils are made overseas, sadly, for those of us wishing a domestic-sourced product was easily available.

[Sam Farrington]

Because I am unable to construct a silnylon tent that remains taut and stable when its gets wet, am looking for something else.  (If you are OK with silnylon, go with it.)  And the silpoly cannot match nylon, strength for weight.  So am looking at paraglider and kite fabrics, but have to be patient because shipping from Europe is a bear these days. No problem, because have enough testing to do to stay busy with this project.

One issue for some is the inelasticity of fabric; the thought being that it will not produce a taut canopy.  But it seems Tarptent does pretty well with taut DCF tents, so it may be a problem with a solution.  Or it may be other characteristics of DCF pointed out by Stumphges above that lead to fussy pitch, deformation and wrinkles.  And design also appears to be a contributor to Stumphges’ concerns.

Michael B appears to have found a sweet spot with membrane silpoly.  As we learned from Stephen Seeber’s thread about it, the waterproofness is not consistent.  Also, RBTR’s Justin Oliveri has posted a chart that rates its puncture and abrasion resistance, as well as tear strength as “Medium-Low,” or “Low-Medium.”  This, from a major supplier.

Granted, the paraglider fabrics are “inelastic,” to use Extremtextil’s term, but they weigh close enough to be competitive with DCF.  And they are 6.6 nylon, woven, not unwoven threads sandwiched between extremely fragile mylar like DCF.  And am not convinced that an inelastic material is a disqualifier for use as tent canopies, so long as it can hold its shape.

So am busy testing the effects of moisture on paraglider materials, as well as resistance to wear, punctures and tearing.  So far, it seems that the inelasticity reduces the expansion and wrinkling of the nylon, but some PU coatings reduce puncture and tear resistance.  So will try some other coatings to up water resistance.  If there is progress on that front, will see if the material has enough bias stretch to conform to a freestanding framework and stay taut in wet weather.  If that all turns out well, it’s go time.

Here is a link to a thread on a French paragliding site that went on from 2016 to 2018.  Note the concerns, as well as the photos around pages 10- 11 of tents that were constructed:
https://www.randonner-leger.org/forum/viewtopic.php?id=21482
The Google translator should come up also. It leaves much to be desired, but is intelligible-mostly.

There is no doubt in my mind that woven fabrics, better than DCF, can be made, and for a much lower price than DCF.

[Dan @ Durston Gear]

Do you have any idea how paraglider fabrics avoid expanding when wet, if they are also nylon 6,6 (which expands by ~2.2%)? It sounds like paraglider fabrics are just more nylon, but perhaps they have figured something out.

[Sam Farrington]

Dan,

The fabric is treated to make it less elastic, because that is what the paragliders want.   But don’t know the composition of the treatment.  Porcher, the manufacturer would know.  It is a ripstop, and what Porcher puts in the ripstop or in its coating may be proprietary.  Porcher does state that the coating is urethane based.

After treating it with thin layers of Gear Aid Tent-Sure on both sides (to increase waterproofing), tested it in my embroidery loops in nasty weather and found it held its shape much better than any silnylon tested.  That was the good news.  The bad news is that after the Tent-Sure was applied and cured, the fabric could be torn by hand, while it could not be prior to the application.  So will try coating on just one side and see how that goes, and will try other treatments to up the waterproofing.  Also, have ordered a slightly heavier sub-one oz material woven with a slightly heavier thread on either the warp or the weft, and a ripstop that is 4mm square vs 7 mm on this one.  And have also found a similar fabric that is polyester, but also not tested yet.

The inelasticity of the fabric may be a turn off for some; but have seen how well some tentmakers (Locus, TT, MLD) have done with DCF, which is totally inelastic, so don’t think that will be a problem, and could be an advantage with a woven fabric with some bias stretch.  What is a problem is that with the TentSure, the fabric becomes more crinkly and might be noisy, which is a big negative.  But have some ideas to try that may address that with other treatments to up the waterproofing.

What is a must for me is that the fabric is woven very tightly, so can be sewn, just so long as the added waterproofing does not make it brittle.  The current project is a self-supporting, or partially freestanding tent, and while it is designed with emphasis on KISS, it will still be much easier for me to tailor and put together with sewing.

So there are still unexplored options.  The projected solo tent uses under 10 yd2 of fabric, not counting the inner ceiling, the inner netting and the floor, so if the fly and vestibule fabrics can be kept to under 1 oz/yd2, it will save 2-3 oz compared to using 20D silcoated ripstop polyester.  It’s surprising how little weight savings really come from using sub-one oz canopy materials; but every bit counts and with other weight trimming should add up to a respectable figure.  I’ll post progress reports.

[Dan @ Durston Gear]

Very interesting. Thanks for the update.

[Sam Farrington]

Read a post on BPL about failure of DCF adhesives as temps sink close to zero degrees F.  This may relate to some of the failures noted in cold weather.  Dirtbag:  When young and dumb, I too slept outside a shelter while the other guys stayed inside.  Froze my keister off.  Never again.

(Note:  Still intend to post progress reports on paraglider fabrics as promised here.)

[Sam Farrington]

Something amazing happened.  Went back and looked at one of R Nisley’s 3 silpoly HH tests for RBTR done in 2015 and posted on BPL.  At that time, RBTR had just come out with a product called Membrane Silpoly CG – PU 2000.  Even after all of Richard’s simulated aging (“5400 wet-flex cycles’) the fabric maintained an HH (hydrostatic head) of 3514mm, while the others he tested, including a sil/PU blended membrane, came out in the hundreds.  This reminded me that I had bought a lot of the Membrane Silpoly CG – PU 2000 in 2015, but had set it aside because the PU 4000 stuff I bought with it lost its tear resistance when I stretched it over a scale model frame. So dug out the membrane silpoly PU 2000, and it is in really good shape.  It weighs 1.1 oz/yd2.  It has the qualities needed for a canopy:  Some bias stretch; no sag when wet; and super HH; but AFAIK it is no longer offered.  Just the membrane silpoly PU 4000, and the membrane silpoly coated with a blend of sil and PU that seems to have lost its charm.

Some may remember from a thread started by Stephen Seeber not long ago that I twice ordered some of the current membrane silpoly from RBTR, but both orders did not exceed 500 mm HH after aging, so gave up on it.  Not a surprise, seeing that the blended membrane silpoly tested by Richard for RBTR in the same 2015 thread also tested poorly (633mm new/492mm aged).  Why RBTR dropped the good stuff is a mystery.  Best guess is possible quality control issues at the source.

This begs the question of what to do with the Skytex 32 paraglider fabric I bought from Extrem Textil.  It does not have good bias stretch ideal for a tent canopy, but will see if the HH can be upped with a coating of either Permatex sil sealant or TentSure PU on just one side.  As reported above, I found that the TentSure PU coating on both sides weakened an even lighter Skytex 27 fabric.  The 32 has a very tight nylon weave, a smaller reinforced ripstop (4mm), low elasticity, and weighs .95 oz/yd2 new with its very light PU coating.  So think it will make a great bathtub floor with a bit more waterproofing facing the ground, and its own light PU  coat facing up with less slip than silnylon.

So may be able to get back to building a tent, and hope that RBTR beefs up its current membrane silpoly for others who want to be able to tailor and sew without depending on adhesives to hold a DCF tent together in monster winds, rain and cold.

Apologies to those disinterested in MYOG.  We got into this discussion here in connection with possible substitutes for DCF, which if you can find it, has a number of drawbacks mentioned earlier in this thread.  Once I’m sure of the materials, will start a new thread on the MYOG forum.

[Sam Farrington]

“… a product called Membrane Silpoly CG – PU 2000”

After further testing of the above product, the resistance to rips and tears is not comforting.  And Extrem Textil is out of the Skytex 32 gram paraglider fabric in a stealthy green.  It seems that the very light polyester fabrics do not tolerate PU coatings well.  So back to the drawing boards.  May try the sun yellow in the 32 gram fabric, all stealth considerations aside.  Will need to test the 32 gram for sag when moist and with some different coatings to beef up the water resistance.

You folks who have not fallen prey to MYOG just don’t know what you’re missing.

[Roger Caffin]

It seems that the very light polyester fabrics do not tolerate PU coatings well.
Expected.

Even nylon with a PU coasting sees a huge drop in strength compared to the uncoated fabric. The reason for nylon is that the PU coating behaves in a ‘rigid’ manner and concentrates the stress in a tear onto the nearest one or two fibres. So the PU-coated fabric tears more easily.

On the other hand a silicone coating is quite stretchy and so it distributes the forces over a lot of fibres. The result is that a silicone-coated fabric can have a tear resistance higher than the basic fabric.

In general a polyester fibre is not as strong as a nylon fibre.

Cheers

[Sam Farrington]

No argument there, Roger.  We are fortunate to have someone on BPL who worked in the fabric industry.

Since polyesters, nylons, and coatings vary, I have to find these things out by experimentation.  Am wondering if Permatex sealant, spread very thinly over an even thinner PU coat on paraglider fabric, will boost water resistance.  The knee-jerk answer is that silicone and PU don’t mix.  But the PU coatings on paraglider fabric are minimal, and Permatex sealant adheres to the sealants and other materials found on windshields.  Also, some of the paraglider fabrics are coated only on one side, as noted in the long thread on the paraglider site (link posted above).   Somehow Porcher is able to coat 6.6 nylon very thinly, but also in a way that the result is “inelastic,” yet maintains resistance to tearing, to quote Google’s translation from product specs on Extrem Textil.  And we know that some fabric coatings are a “blend” of Sil and PU, so say RBTR.  It is a WIP (work in progress).

With respect to, “In general a polyester fibre is not as strong as a nylon fibre.”:  Yes, and suppose that is why paraglider fans are not flying around in the sky held up by polyester.  I’ll stop there, hoping to avoid yet another long contested thread on that subject.

Have read the latest version on BPL rules about thread drift.  Whether the WIP has anything to do with “DCF prices going up” is “arguable,” as the lawyers say.

[Eric Blumensaadt]

Kinda glad I have had  a gen. 2 TT Notch Li for over a year. I dyed the inner green with DyeMore synthetic dye and sewed four extra stake loops attached to reinforcements around the fly hem for very windy nights.

But DCF’s high price is not only “somewhat offset” by its light weight but also the lack of stretch and its strength. I don’t regret paying for the Notch Li any more than I do paying for my Western Mountaineering Megalite mummy bag.

So my little solo DCF shelter should keep me safe and dry in most conditions including a moderate snowstorm. Not that I’m afraid of snow because I love winter camping. It’s just that the Notch Li is not made for a lot of snow – better than many DCF tents in this respect but snow is not its forte’.

 

[Sam Farrington]

Eric, thanks for sharing that the Rit Dyemore works on your DCF.  Was just thinking about that because Extrem Textil ran out of Skytex 32 in green, and would like to dye the sun yellow that I ordered.  It is not mylar and dyneema, but tightly woven nylon 6.6.  So will color test it on the Rit first.

If you had to go to DCF, TT was probably the wisest choice.  Glad to hear the it worked out.  But snow is not my forte either, especially at night in the White Montains when the temp can drop 20 to 30 degrees.   Occasional snow shoeing on sunny days is as far as I go these days.

[Roger Caffin]

I can confirm that you can dye nylon very well. We dyed our nylon climbing ropes with hot water and some sort of dye (possibly RIT) , about 50 years ago. The dye is still stable.

Cheers

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