RSBTR 7d MTN Silnylon 6.6 now available in dark olive and blaze orange

[Monte Masterson]

RSBTR has had the black and gray 7d available for awhile, but now there’s a little more variety of colors.

https://ripstopbytheroll.com/products/0-77-oz-mtn-silnylon-6-6?variant=32425411117104

[Stumphges]

Has anyone made a small pyramid tent with this stuff?

[Jerry Adams]

hmmm…  my tent weighs 13.5 ounces, 0.93 ounce silpoly

maybe 12 ounces is fabric, so that would save 2 ounces to do it with this silnylon

but it will stretch and the tent will get loose if the temperature changes/it gets wet

[Monte Masterson]

Yea Jerry, but as Kyle says in the description “20% lighter than our Membrane Silpoly with roughly 2X the tear strength.”

I’m one of those who believes too much is made of the stretch of silnylon. Besides, in strong winds a little stretch can be a good thing.

I don’t know of anyone or any company who’s made a mid with 7d, however, there are a plethora of tents being made with 7d silnylons.

[Stumphges]

Monte,

This topic came up in the active thread on tent floor materials. Xavier from Tipik came by to share his tear strength measurements, which don’t line up with RBTR’s claim: https://backpackinglight.com/forums/topic/yer-experience-with-dyneema-tent-floors/page/3/#post-3682294

I noticed that RBTR does not have tear strength numbers in their spec sheet for the 7d fabric.

It would be good of Kyle to drop by and clear things up.

[Monte Masterson]

Thanks Stumphges. I wasn’t aware of Xavier’s tests nor was I following the thread because I’m not an engineer or a materials scientist and the discourse is over my head. Though it would make sense that a 7d silnylon wouldn’t have 2X the tear strength of 15d silpoly. Nevertheless, I know I got some readers ticked at me recently for doubting HH measurements on RSBTR’s 1.1 oz silpoly, however, the data was only from ONE TEST. Didn’t mean to throw any shade, but I inherently doubt everything, just like I should have doubted RSBTR’s claims about the tear strength of their 7d MTN silnylon.

I see Rockywoods has tear strength claims on their 7d silnylon of 1.2 lbf in the warp and 2.5 lbf weft. I don’t know what any of that means or how that compares to RSBTR’s MTN 6.6, though I’d certainly think the MTN 6.6 would be superior to Rockywoods’.

https://www.rockywoods.com/7D-Ultralight-Coated-Ripstop-Nylon-Fabric

[Stumphges]

Monte,

Yeah, you gotta think that the 7d MTN is stronger than the sil/Pu stuff that Rockywoods has. And it does stand to reason that 15d poly would be stronger than than 7d nylon, even 6,6 nylon.

But I asked if anyone had made a mid with it cuz we have a claim made by the vendor and some data supplied by a customer of the vendor that contradicts that claim. So some real-world experience would be illuminating. (And so would a word from RBTR).

[Monte Masterson]

But 15d Membrane silpoly isn’t a ripstop fabric correct? And the 7d MTN 6.6 sinylon is ripstop. Seems like that would make a huge difference. And if silpoly is so good why don’t more mainstream tent manufacturers use it instead of opting for nylon? Marmot makes many of their tents from polyester and SMD mainly uses it, but Big Agnes, MSR, Nemo, Sierra Designs, and practically all of the European tent makers (Nordisk, Terra Nova, Hilleberg) use nylon (a lot of 7d nylon). No 15d membrane silpoly being used by any mainstream manufacturers I can see. Correct me if I’m wrong. Not many making tents from polyester of any type.

I don’t have anywhere near the science background that many posters here on BPL have and I’m humbled, but I’ve always thought that results needed to be corroborated by more than one tester (preferably 3 or more) before data is automatically accepted as fact.

 

[Jerry Adams]

some people believe that ripstop is not really all that effective, more marketing.  I prefer non ripstop but I’d use it if that’s what was available.  I can’t think of a time fabric has ripped on me.

any manufacturer like tent makers are conservative.  Reluctant to switch to something different

the advantage, that polyester doesn’t stretch as much when it gets wet (or cold?), is subtle.  If you have to tighten the tent up a little it doesn’t make that much difference.

[Stumphges]

Hey Monte,

I’m with you on all points. It would be nice if RBTR came by to share their tear strength data for 7d MTN silnylon and 15d Membrane silpoly.

I suppose you and I could get some of each and do some home testing as well;)

[Mole J]

Monte wrote:. “Correct me if I’m wrong. Not many making tents from polyester of any type.”

 

Not “our sort” of backpacking tents, but the vast majority of cheaper tent canopies are made from pu coated polyester fabric, not nylon.

 

[Sam Farrington]

Monte,
Re: “I’m one of those who believes too much is made of the stretch of silnylon. Besides, in strong winds a little stretch can be a good thing.”

And Re: “0.77 oz MTN Silnylon 6.6” from RBTR.

RBTR used to have one dashboard on one site page that showed all the fabrics. That is no longer, so one can get confused.
In determining color for this fabric, would also suggest ordering a set of the fabric samples before investing. It is not a ripstop. If it were, the site page would say so.

Silnylon, and nylon in general, has stretch parallel and perpendicular to the grain. It also stretches more diagonally to the grain, or on the bias as some say. Quite apart from that, silnylon wil expand in moist conditions making any flat, unsupported panel on a tent sag. That sag is what is unpopular, not the stretch.

It may be that in dry areas, there will be little sag. But in the Rockies and the East Coast, the sag can be pronounced. A good thread that illustrated this was on BPL years ago by a guy who posted as, “Hang ’em High.” He was subjected to much ridicule, but his thread illustrated the point well: With a silnylon tent, the canopy will sag when moist and impinge on the internal volume of the tent. Some kind of dome or tunnel framework can limit this. But on a tent that is mostly unsupported flat panels, like an A-frame, or Trekking pole supported tent, when the panels expand, space can become quite limited in a single wall tent.  Especially on an A-Frame that tapers down to smaller cross-section over the feet, of which there are many on the market even today. And with a good dose of wind, water will fly about, especially when getting in or out of the tent.

It is true that silpoly (silicone coated polyester) fabrics do not sag like silnylon. And the 20D (denier weight) silpolys are sturdy enough to function well, so are desirable on a Trekking Pole tent. However, the 7D Membrane silpoly from RBTR is a much lighter and thinner fabric. Would suggester ordering a yard for examination and testing before investing for use as a tent. There is also a membrane 15D silpoly from RBTR that is about halfway between the above two in weight. Unlike the 20D, it is not ripstop as the term ‘membrane’ suggests. I ordered the 15D when it first came out, and did not find it satisfactory, as outlined on the thread about tent floor materials.
So suggest the same caution as with the 7D.

[Tuukka U]

Sam: The MTN 7D Silnylon does have a mini double-grid ripstop mentioned in the specs.

I find the concern about sag somewhat strange. I guess it depends on the tent design, but simply tightening the tieouts again once the sag has set in has always solved the problem for me.

[Monte Masterson]

Yea Sam, as Tuukka U says, the RSBTR 7D MTN Silnylon 6.6 is absolutely a ripstop. A true silnylon too, none of that PU stuff. I don’t know how the material stacks up to what Nordisk uses on their 7d nylon tents, but I’ll bet it’s pretty high quality. Guess I’ll have to break down and buy some. Of course at $14.95 per yard it ain’t cheap.

 

[Stumphges]

Nordisk say their 10d silnylon has tear strength at 8 kg (17.6 lbs).

https://nordisk.eu/telemark-2-ulw-forest-green/forest-green/p/364/2253

Meanwhile, MLD claims their 20d silnylon is also 8 kg.

hmmm

Xavier previously tested extremtextil’s 20d silnylon at about the same 7 kg, and 15d Membrane silnylon at 3 kg

From: https://www.randonner-leger.org/wiki/doku.php?id=mesures_textile

In a neighboring thread, Xavier kindly provided a measure of 1.9 kg for the 7d MTN silnylon he bought in 2019. Noteworthy that he also found its puncture resistance to be good enough to speculate if there might be some PU in its coating.

Taken as a group, the Nordisk 10d seems a big outlier. If RBTR’s claim about MTN 7d were true, it’s tear strength might be around 6kg, which would also be an outlier.

 

 

 

 

 

[Sam Farrington]

Tuukka U and Monte M,

Thank you for bringing to my attention that the 7D Mountain silnylon 6.6 from RBTR has a mini-grid ripstop.  My apologies for suggesting otherwise.  Looked at my black version under strong light and could see the grid.  Interestingly, the grid looks very similar to that on the Rockwoods gray 7D, albeit the RW has different coatings.

And Monte, thank you for alerting us to the new colors.  Immediately ordered a couple samples, for the gray and for the dark olive to see how they compare for light transmission.  In one of the RBTR product page photos, the mini-grid showed up very clearly.

As far as the strength, durability and water resistance are concerned, agree that they are not clearly established.  RBTR says ‘~2000mm,’ meaning it is an approximation, and would drop considerably after simulated aging.   Also, the fabric is very supple, like silk, with little if any body or stiffness, and would be a bear to sew.  If anyone knows of an HH or other test in addition to Xavier’s on the floor thread, please post.  The Rockywoods 7D HH was posted by Richard Nisley at (scroll down):  https://backpackinglight.com/forums/topic/108230/

Please note that 20D fabrics can weigh as little as l.06 ounces/sq/yd, such as the 20D silnylon from Extrem Textil.  As for how they got it so light, can only guess, and that would be a lower thread count.

Was thinking that if the new colors on the RBTR 7D MTN sil are lighter, might try a tent fly; but will see what the weight savings will be before putting in quality time.

[Stumphges]

Sam, very good point. Difference between 1.06 oz/yard (Extremetextil 20d silnylon) and 0.77 oz/yard (RBTR 7d MTN silnylon) might equate to 2-3 ounces on a small pyramid tent like a Duplex or Khufu, maybe less. Why are we even discussing this fabric? :)

[Sam Farrington]

Stumphges,

That difference is around 0.29 oz/sq/yd.  I’ve found that in attempting to make a woven fabric tent as light as possible, every little bit of weight savings on each and every component is the name of the game. The total weight savings really do add up, much beyond what I would expect.  Recall a similar sentiment on BPL recently from another MYOG fan.

The hard decisions are about not going so light that either comfort, function or safety will be compromised. This process might be termed ‘careful light,’ as opposed to ‘stupid light’.

For me, the discussion about this fabric is to see if the other colors are light enough in color for a tent that is pleasant to be in, as opposed to the inside of a bat cave.  Not to take anything away from Bruce Wayne, who lived in a mansion – but not a shelter suitable for carrying on the back.

[Monte Masterson]

For me 0.29 oz per square yd is a big deal. I made a Hexamid Solo Plus copy out of cheap 30d and 20d silnylons last Winter as a mock up and it ended up weighing 11,3 oz. But with the 7d MTN 6.6 I could get that down to about 7.75 oz.

I don’t doubt that the Extremtextil 20d silnylon is maybe the best quality for the weight (weight of most 15d’s) however, I don’;t know about shipping from Germany. Probably not much of and issue really. And again even 1.06 is heavier than what I want.

I sent an e-mail to RSBTR about addressing concerns regarding the 7d MTN silnylon 6.6 on this thread and an associate replied back and said they’d tell Kyle about it. We”l see if he responds.

[Sam Farrington]

A big deal for me also, Monte, but am not sure I’ve got as much confidence as you about the quality of the Extrem Textil 20D silnylon.  Earlier, I speculated that the lower weight could be due to a lower thread count.  If that were so, don’t think that a lower thread count is a plus for any woven fabric I’ve run across.  And there was the thread about the unraveling of that 20D, as well as my mysterious experience with a yard I ordered unraveling when cutting test sample.  And a couple months later, the same swatch not unraveling or even fraying when samples were cut the same distance from the selvedge.  Maybe someone with experience in manufacture of woven fabrics can provide some idea of what was going on.  I can’t, though.  So there are some reservations.

All of which may be academic, as you say you are looking for something lighter.  Putting aside for the moment those who believe 6.6 nylon is not much more robust than RBTR polyester of the same weight, your quest for lighter weight, even with nylon, could be an overreach, despite the popularity of their 7D silnylon as evidenced by this and other threads.  I found a post on Reddit about a 15D silpoly tent coming apart when almost new.  I’ve never seen anything like that about a 6.6 20D silnylon, which but for the above concerns about the strange behavior of Extrem Textil 20D, would make it a safe bet.  But I sense that the 20-30D 6.6 silnylon from Thru-Hiker, at 1.4 oz/sq/yd is much heavier than you want.  Even a 20D polyester from RBTR, at 1.24 oz/sq/yd beats that for the reasons discussed above about what is significant with weight differences.

Sometime ago, Moderator Roger Caffin posted that he first looks at what fabrics are sufficient for his purposes, and accepts only the lightest weight that meets them. (my words, not his, as time does not allow for digging out the quote).   Every time I get the urge to go superlight, as with the fabric that is the subject of this thread, I hark back to Roger’s M.O.  What good is superlight if the product is not going to protect us when a horrendous storm arrives around bedtime or later (If it came earlier, I’d beeline to a safer campsite), or if the tent doesn’t last much longer than the time invested in making it.  It would be nice if we had hard engineering and scientific testing to help us decide how low in weight  we can safely go; but I’ve yet to see it.

So with the time and effort it takes for me to build a tent, I lean toward something a little heaver than 7D.  There is often a lot of CYA language from the sellers of 7D.  I’ve also decided to use polyester for the part of a tent that cannot be permanently stretched on the bias while erected (sort of like pre-bending tent poles).  So I”ve also sent an email to RBTR pointing out that some of their breathable 15D camo polyesters have a micro-grid ripstop, so why not coat such a fabric to make a 15D micro-grid silpoly?  I think I would be willing to take a chance with that for the vestibules, and maybe even the outer fly, which requires some bias stretch.  But since their 15D silpoly is 0.9 oz, it would probably go a little over one oz/sq/yd after coating.  So it also might be too heavy for you, despite the abilities of silpoly to not get soaked and not to sag.

If we want material well under one ounce/sq/yd, maybe it is time to take the plunge with DCF.  Recently, @kurogane posted on another thread that he is getting unbreakable bonds with DCF without the need for oversewing (except maybe for stake and guy point reinforcements), and was kind enough to post sources of his adhesives and materials.  Like polyester, DCF doesn’t soak or sag;, however, polyester does have some bias stretch, which is a big plus for me in tent making.  Which is why I made the suggestion to RBTR.  Who knows, maybe they will put 2 + 2 together and … Voila!  If so, I’m glad this thread got me to focus on the micro-gridstops.

BTW, after some emails and delays, I found that Extrem Textil would ship to the US with a higher delivery cost, and was good enough to set up a link to make it easy to add the expense to my orders.  What they will do after the pandemic is unknown.  Were I younger, I would get drunk.

[Michael B]

What kind of loads do small pyramids see in typical usage? I look forward to seeing some proper specs from RBTR to you guys, but I have noticed on my experience with membrane silpoly (just a couple flat tarps so far) that I have been more concerned about tear propagation, and nylon, even plain nylon-6 fabrics seem to do better than the poly. Once you start tearing poly, it seems to just keep on going, wear nylon has a bit of a tendency to “pucker up” as you try to continue to tear it. I am sure others here have a lot more experience than me with this and maybe my experience is purely anecdotal and subjective.

I am curious to see how the fabrics specs match up with tent/shelter product requirements. IMO, a properly engineered and optimized product has target numbers for both the requirements and the materials verified to meet those requirements, but even at my day job, many engineering tasks stop at “that will work” or TLAR “that looks about right “. Far from optimal, and often products are overspecd in some areas and underspecd in others, sometimes causing the cost of the product to be much higher than it could be while still fulfilling the mission.

[Jerry Adams]

“I am curious to see how the fabrics specs match up with tent/shelter product requirements. IMO, a properly engineered and optimized product has target numbers for both the requirements and the materials verified to meet those requirements, but even at my day job, many engineering tasks stop at “that will work” or TLAR “that looks about right “. Far from optimal, and often products are overspecd in some areas and underspecd in others, sometimes causing the cost of the product to be much higher than it could be while still fulfilling the mission.”

Then they must not have engineers – “it takes an engineer to build a bridge that barely stands”

Yeah, a lot of products are built with overly heavy materials.  Then they don’t have a problem with it failing, but it’s heavy.

I’ve used my membrane silpoly mid for quite a while without any problems including some wind.  Now you have me worried.  I should take a piece, cut a short slit, and see if I can then pull it apart.

 

[Michael B]

If you keep some tenacious tape on hand for the occasional “oops I just threw a stake through my tarp” moments, you should be ok. That is why I question the requirements. I think all of us want robustness, but we don’t really make an effort at defining what “robust” means in the real world, with actual numbers.

We have real engineers at work (myself being one of them), but program management decisions often trump good engineering suggestions.

[Dave @ Oware]

How does that tenacious tape stick to silicone coated fabrics?

[Adam Kilpatrick]

There is a silnylon version of tenacious tape now. No idea how well it works though

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