#Moonlight tent …

Spinnaker was popular until the water proofing became unreliable. MLD, GG, and others were using it as the premium priced option in shelters before Cuben became the hot new thing.

Somebody looking to do a production run, in collaboration with a production facility, may have access to materials from suppliers in volumes and prices that aren't available to the general public.

Lawson – THANKS!

Woubier – HA! Nabbed by my own over-generalization! OK, let me modify it with a wiggle-word or two: "ALL larger tents from conscientious suppliers are now polyester." Maybe it's my US provincialness showing. I wouldn't put it past W-mart or Tr-gt or any number of c-class tentmakers to use nylon in a bigger tent.
Hey, wait a minute. One can juuuust get nylon to work on a 4-person tent but…
Polyester rainflies:
Vaude, http://www.vaude.com/de-DE/Produkte/Zelte/5-und-mehr-Personen-Zelt/Badawi-Long-6P-sand.html
Nordisk, http://www.nordisk.eu/products/tents/fabric/
Helsport, http://www.helsport.no/varanger-dome
Salewa, http://www.salewa.com/en/denali-iv-1-1.html?color=8665
jack Wolfskin, http://www.jack-wolfskin.com/equipment/travel-equipment/tents/family-tents/3002431-great-divide-rt.aspx
Terra Nova, http://www.terra-nova.co.uk/tents-and-spares/all-tents/etesian-4-tent/
even Field Candy, http://www.fieldcandy.com/tents/original-explorer/what-a-melon.html
Who did you look up and how big was that tent?

FG – the lightest polyester fabrics that I've seen that I consider strong enough are 20D. Less than that and it's only nylons. I would love love love to have 15D and 10D and lower polyester fabrics that could work. Also remember that the sagging comes from setting it up and then having it get wet. Setup in high humidity conditions mitigates the change when it gets wet (it may already be nearly fully expanded).

THANKS!
Mike

I'm a hiker more than a camper, so my shelters are typically set up late in the day/early evening and taken down early the next morning, but for feces and giggles…

How does polyester hold up to UV light vs silnylon? Truly a question and not an attack, as I don't know.

"Setup in high humidity conditions mitigates the change when it gets wet (it may already be nearly fully expanded)."

I live in the one so that is why I don't have a problem with sagging or expansion, or growing, or lengthening, or swelling, or fatting of the textile.

It may not be raining but the humidity is there. We get 'clouded' on all winter

"Setup in high humidity conditions mitigates the change when it gets wet (it may already be nearly fully expanded)."

What is the maximum stretch that one can expect with silnylon in those conditions? My experience has been that it stretches quite minimally.

Mike,
I looked up 6- to 8-person tents from TNF, MHW and Marmot, exspecting to see at least a polyester fly on some of those tents. To my surprise, all had nylon flies. B
Sure, polyester works as a fly. We have a cheap 6-person tent with a polyester fly and it works great.
The question is why do those brands use a polyester fly ? E.g. the Vaude Badawi. I know that as that was 1 of the options when searching for a familytent. And it's already costly tight now with a polyester fly (something like 1000 $ or more). My guess is that if they would use a nylon fly, this model would be even more exspensive.

"The newer silnylon with high hydrostatic head does not sag very much at all (I am assuming that the term 'grow' means sag)."

Dang, I'm getting jipped! My Solomid XL sags/grows like crazy in an overnight rain. MLD uses a very high HH silnylon and it probably sags less than others, but it still sags quite a bit(or at least more than I prefer). Very possible that cuben has spoiled me in this regard though.

Ryan

Still and all, I think Mike and Lawson have brought some interesting info to the table. I thank them for this. After all, there was a time when tents were made from japara – a long-staple egyptian cotton fabric. Nylon replaced that. I still have a japara tent in the cupboard. So further progress is possible.

It would seem that we should keep an eye on high-tenacity polyester, especially if some mill decides to use it to make a good silpoly. But can we ask them PLEASE to make it a plain weave, NOT a ripstop? The HH will be so much better without those big ripstop threads upsetting the weave. The so-called ripstop threads add little or nothing to the tear strength of silnylon these days.

Cheers

Woubier – Marmot uses polyester rainflies: http://marmot.com/products/details/halo-6p
MHW does too: http://www.mountainhardwear.com/optic-6-1568191.html?cgid=equipment-tents-camping&dwvar_1568191_variationColor=456#start=0
And so does TNF: https://www.thenorthface.com/shop/equipment-tents-4-person/kaiju-4?variationId=M6P
Are you only looking at their "expedition basecamp" tents?
-Mike

I think so. I just quickly looked for the biggest tents I could find in their range. But was it not about all big tents using a polyester fly ? As I don't remember reading that certain types of tents were excluded.

"Dang, I'm getting jipped! My Solomid XL sags/grows like crazy in an overnight rain."

Sounds like a benefit. Start as a SoloMid; end as a DuoMid. You are getting more space for the same weight!!

Ha! Well played sir. Nylon wins this round!

Ryan

Well, we have quite a holistic discussion of tent fabrics going on here already, so i thought i would throw this in also and ask the experts.

Why do we never see polypropylene tent fabrics? Is it more because of marketing or sheer material practicalities/problems (or a combo)?

Some pros and cons of polypropylene as compared to polyester and nylon as i so far understand it:

Significantly lighter than even nylon, with similar, but slightly less tenacity than common polyesters. Innately quite hydrophopic, significantly even more than polyester. Slightly stretchier than polyester, but less than nylon.

Almost as cheap as polyester, as it is readily recyclable and fairly commonly recycled (though not quite to the degree of polyester).

Perhaps the worst characteristic is that it's more UV sensitive than nylon, but there are ways around this, such as mixing carbon in.

It's impractical to apply a "coating" like silicone to it, BUT why couldn't you take a tightly woven fabric, and lightly melt a thin layer of nonwoven polypropylene film into the woven part filling in the interstices–polypropylene will readily heat bond with polypropylene (and at relatively low temps, but higher than nature provides). In theory, such a method could last much longer than the typical silicone coatings which have a weaker bond than the former would offer. The former would also tend to have a higher HH as a film is going to tend be more uniform, likely thicker, and again more strongly bonded than an applied coating.

So what am i missing and what's not to like? If such a material could get to around 1 oz per yard2 or slightly less, i would be pretty happy with all the combined features.

(i also don't understand why "cuben fiber" isn't made with UHMWPE fibers sandwiched between two thin layers of UV treated UHMWPE film, instead of weaker mylar, increasing strength, durability, and foregoing the need for plasma treatment of the UHMWPE fibers thus potentially decreasing cost of manufacturing some).

Well, good question.
Polypro does have some limitations:

(quote from web)
Low melting temperature which prevents it from being ironed like cotton, wool, nylon
etc.
Hard to be dyed after manufacturing, except after substantial treatment and modification
High crystallinity and poor thermal conductivity leads to limited texturizability. Poor UV and thermal stability which requires addition of expensive UV stabilizers and antioxidants to overcome this problem
Poor adhesion to glues and latex
Flammable which melts and burns like wax.

Heat setting removes the residual strains and produces a defect-free and stable crystalline structure to make fiber/fabrics dimensionally stable. It also improves the percentage of overall crystallinity. The smectic structure changes to more perfect monoclinic structure during the process of heat setting if the temperature is above 70 C . At 145 C the conversion is almost complete. In comparison to predominantly smectic form, the monoclinic form does not experience any major change in crystalline structure during the course of drawing and heat setting.

Mechanical properties
The general physical properties of PP fibers are shown in Table 1. Polypropylene fibers are produced in a variety of types with different tenacities designed to suit varying market requirement. Fibers for general textile uses have tenacities in the range of 4.5-6.0 g/den. High tenacity yarns up to 9.0 g/den are produced for the use in ropes, nets and other similar applications. High performance PP fibers have been made with high strength and high modulus. The techniques include ultra-drawing, solid state extrusion and crystal surface growth. The filaments with tenacities over 13.0 g/den can be made.
(end quote)

So dyeing it is difficult, bonding it is difficult (so coating is difficult), it degrades under UV and it does not like high temperatures. You can see the limitations.

I suspect the real problem is that the incumbents, principally nylon but also polyester, leave little incentive for serious investment.

Cheers

Thank for the reply and info Roger.

You wrote, "So dyeing it is difficult, bonding it is difficult (so coating is difficult), it degrades under UV and it does not like high temperatures. You can see the limitations."

These were all mentioned and addressed, except for the dyeing, which while may be an issue for companies worried about sales to the market, is of little importance to me because it's a completely superficial concern. Besides, while PP isn't conventionally dyed per se, like nylon or some polyesters, color is added to the plastic in it's liquid state before it's extruded. Hence, it can be colored easy enough (and any color), and it's quite permanent as compared to more conventional dye and dyeing.

Rather than coating it to achieve waterproofness, you could just heat a thin film of P.P. and melt it into the woven PP fabric. Since they are the same plastic material, they will bond well from heat, and if you do this carefully at controlled temps and timing, could do so without weakening the woven fabric much at all.

UV handling can be greatly improved by additives like carbon.

Personally speaking, i would love to experiment and use such a material for a tarp or tent. If only i had money and/or connects…

In my opinion, the best UL shelter fabric would look like this.. A 20d Polyester with a 50d Dyneema/Spectra grid stop every 1/8". The fabric is hot calendared and then silicone coated on both sides.

If you make a mid out of this Mike, I will be your first Kickstarter supporter. Just let me know where to mail the check : )

If it's hot calendared after the UHMWPE fibers are added, that could potentially weaken them a lot, as UHMWPE is very sensitive to strength loss at relatively low temps. Even worse than PP in that regard. I tried to heat bond some UHMWPE films with an iron on a relatively low temp setting, and while i could heat bond it some, the material at the bond became pretty weak. So i know this from both theory (reading about it) and some experience.

Perhaps put the polyester fabric through that process first, and then add the UHMWPE fibers after?

Hi Lawson

> A 20d Polyester with a 50d Dyneema/Spectra grid stop every 1/8". The fabric is hot
> calendared and then silicone coated on both sides.
Forgive me, but … it will leak like a sieve.

The large ripstop threads create huge holes in the weave which halve or worse the HH you can get. And with a good silicone coating, it turns out the threads do not add anything useful to the tear strength, as the silicone impregnation takes over.

Now, leave the ripstop thread out, and the fabric would be interesting.

So why does everyone want ripstop? It's a marketing thing: it sounds technical, and most customers wouldn't know any better. If you want photos, just say so. They are already posted in other Forum channels anyhow.

Cheers

Snowpeak uses a 20D Polyester on the fly of their Lago 2. The floor is a 30D Polyester, so there are fabrics out there. So far mine has performed well.

Good point Roger. It seems that most woven fabrics, commonly used for such materials, nowadays are strong and durable enough for tent and tarp material without ripstop.

So yes, kind of pointless. To save weight, rather than go with an ever thinner and lower denier fabric + ripstop, just use less dense fabrics or materials to begin with.

One could take a woven dyneema/spectra type fabric, and do similar with what i proposed with PP earlier. Fill in the interstices with a thin non woven film of same material, applying just enough heat and pressure to heat bond it with the main, woven material. Only need to do one side.

UHMWPE (especially in the form of dyneema and spectra filaments) IS very fussy when it comes to heat and strength loss, but my understanding is, that there is that perfect temp and timing where it can be melted slightly without losing too much strength. I couldn't do it at home, but i'm sure a clever manufacturer with professional equipment and know how could perfect such a process with a little trial and error.

Such a material would blow everything else out of the water as far as a combo of low weight to high strength and durability, provided there are UV protective additives added to the film and fibers/yarns.

This is my dream material. It would still be expensive like cuben fiber though–possibly more so since there would be more UHMWPE material involved (rather than some cheap mylar offsetting some of the price).

Meanwhile, i would settle for a much cheaper PP version.

I was under the impression hot calendaring was done around 200F. So I was thinking it would align the HPPE warp fibers even more and make it stronger in that direction which is perfect for a mid. This is what Cortland Line does to make Plasma Fiber and is common when you do a double braided rope. You run the HPPE braided core up the middle and use steam to heat set the Polyester Jacket. If hot calendering is done at a higher temp then you are correct. BAD IDEA.

As far as the ripstop goes. I couldn't agree more with you Roger, but there is no such thing as a 20D HPPE. I also do not like a raised ripstop. Stupid. But good for the ad team. I would actually prefer a 50d Polyester fill material over the sissy 20d BUT it would never sell. In my dream, I sell a million yards of this material day, and buy my own country and live in a Tent McMansion. I would call it the SKY DOME. haha

Another thought… A 16×16 100d Spectra Scrim with an 10 gauge PET film laminated to both sides. AKA the Cuben Killer. For 100,000 yards I know two guys that can make this happen

As far as Calendaring goes, you may be right Lawson if the calendaring is kept at that temp. I'm not sure what exact temps they typically do calendaring at. In the case of polyester, because it's fairly heat resistant, i would think they would have to go higher than 200 F even with a lot of pressure involved? Nylon might be calendared at that temp though? It makes sense to me that different materials are going to require different temps, but i may be off.

But as far as UHMWPE goes, these are some of the basis stats:

"The weak bonding between olefin molecules allows local thermal excitations to disrupt the crystalline order of a given chain piece-by-piece, giving it much poorer heat resistance than other high-strength fibers. Its melting point is around 130 to 136 °C (266 to 277 °F),[6] and, according to DSM, it is not advisable to use UHMWPE fibers at temperatures exceeding 80 to 100 °C (176 to 212 °F) for long periods of time. It becomes brittle at temperatures below −150 °C (−240 °F).[citation needed]"

But why not a dyneema or spectra woven fabric, with some UHMWPE film melt bonded into the interstices of same (providing the water proofness) while retaining the basic structure and crystalinity (and thus strength) of the woven yarns/fibers?

As always, there's constantly evolution in what they can do chemical wise with certain fibres, yarns or fabrics. So your choice of dream fabric today could change completely tomorrow.

BTW, I see that there are windows in the rainfly. It happens that we use a tent that has those too and

1. It's the #1 spot where the fly started to leak
2. they became quickly unusable as they discolored and you couldn't see trough them anymore

Anyhow, when we get into the tent, we do that because we want to sleep and not because we want to see the stars. And when we get in quicker, we do that because the weather is bad and usually cloudy.

And this is why I like BPL so much. The depth and breadth of knowledge here is amazing, and people are very willing to communicate intelligently (well, mostly) about these issues. I much prefer how this conversation is ending up, as opposed to the Gear Deals post it was supposed to be. Thanks everyone.