HH Test of Rip Stop by the Roll 15D Membrane Silpoly
Mar 14, 2021 at 10:37 pm #3704665
Thanks for testing these, Stephen. It gives me a bit more confidence in the yardage I have at home waiting for a tent to materialize.Mar 14, 2021 at 10:56 pm #3704669
The lime green large samples of membrane silpoly that I furnished to Stephen were ordered and received from RBTR on a roll last month, and cut from that roll. It now appears there was a defect in the material.
On one hand, I’m delighted, because my original goal of using the fabric for a fly again appears feasible. On the other hand, I’m not sure how to proceed.
A month or so before ordering the roll, I did order a couple yards of the material in lime green, so I’ll contact Stephen and see about testing these, although it is possible they could have come from the the same role. I’ve also noted there are also substantial differences in HH test results depending on fabric color, and that may be a factor, but not to the extent of the different HH test results. I think Stephen’s comments about defects in the fabric are the most likely reason for the poor test results.Mar 15, 2021 at 4:53 pm #3704815
Hi Sam, I personally would not use the defects as a reason to not use the fabric. This type of test really puts an unrealistic strain on any portion of the fabric that might have a defect in it, causing one to believe that the defect will cause much more of a problem than it will in real life. I am definitely repeating myself here, but I think it is worth repeating. If you require a fabric that is absolutely free of defects in order for you to feel it is going to do the job you want it to do, then that is fine. It is a high standard that almost no one in the business is likely to hold their products to. All tents and MYOG fabrics would double or triple in cost if that was the case. Scuffing your finished tent on the ground during use is likely going to cause more of an issue for you (or in my case, throwing a stake through it). Better to spend the time in design a tent around the defects to mitigate the risks of the much bigger problems we see with our tents.Mar 15, 2021 at 5:16 pm #3704818
Better to spend the time in design a tent around the defects to mitigate the risks of the much bigger problems we see with our tents.
Cute idea, but utterly unworkable. If I have a production run of 200 tents, just how can I design each one around the defects in the cloth? That just ain’t feasible.
The idea that fabric can never be free of defects is equally unrealistic. If I am selling fabric with lots of known defects, I am not going to find buyers. I will go broke, fast. Equally, modern weaving machines have to be able to weave defect-free cloth in volume, or the machines won’t sell.
Actually, it is probably the coating stage where most defects can occur. Blobs of coating can happen, usually at the edges, but these too are not going to be acceptable to the buyers. In a competitive world, QC is imperative.
CheersMar 15, 2021 at 5:26 pm #3704821
Sure, roger, I get what you are saying. I think I spoke poorly. I didn’t mean to try to work around the defects. The defects we are seeing here are not realistically going to have any real world impact on the ability of a shelter to keep the user dry. Other design flaws are going to crop up that will have a much higher impact on that – seam type/location, vent size/location, basic shelter size, etc. a few twists in the thread causing test anomalies is not going to cause shelter failures unless literally every square in is covered in them, and even then I would not be so sure it would affect much.Mar 15, 2021 at 9:01 pm #3704880
This leads to the less obvious idea that any really cheap or discounted fabric should be looked at very carefully – for defects. Caveat Emptor.
CheersMar 15, 2021 at 9:22 pm #3704885
Most definitely. I don’t have any reason to believe anyone in this industry is giving more attention to QA of their fabrics than RBTR. Have we verified that any of our cottage manufacturers produce with fabrics which meet the specs they say they do? Just curious, I have only been on these forums for the last year or so.Mar 15, 2021 at 9:23 pm #3704886
Please note what Stephen posted earlier:
“The issue to me is not whether 15D in general is appropriate for the use intended by Sam. I don’t know whether it is or not. It is whether the industry can exercise adequate quality control to deliver what its specifications claim. This is what Sam said: There are a lot of pitfalls in MYOG for those who put an inordinate amount of time into tent making. The MYOGers and small shops should be able to trust they are getting the performance they expect based on dependable specifications. If your samples do well, we have confirmed there is probably a quality control issue. If so, how can Sam know that the lot he purchases will do what it is supposed to?”
That is more eloquent than anything I could say, so will leave it at that. But I’m glad that your swatches of this fabric tested well . It may be that the fabric I ordered was from a bad batch. Regardless of the cause, which is mere speculation, the fact is that the fabric I bought did not test waterproof by any standard, and that is something I’ll need to take up with the seller. It may take some time, but I’ll let readers know how that goes. I wanted to use this lighter fabric, but if RBTR does replace it, how can I now be sure of it? Having been caught in protracted deluges many times, the critical importance of a reliably waterproof fabric has been indelibly impressed upon me.Mar 15, 2021 at 9:51 pm #3704892
Sam, I totally get that. Having just googled “MLD fabric HH”, it seems every tent manufacturer suffers from low HH when independently tested, or at least has in the past. I did refer RBTR to this thread, so I hope you have good success in finding a product from them which works for you. I also hope this dialog leads to a better QC process, but I hope it doesn’t make the cost of buying MYOG cost prohibitive for those of us who are not as concerned with what I think is a relatively low risk.Mar 17, 2021 at 9:25 pm #3705133
Could you explain what you mean by “relatively low risk.” Thanks.Mar 17, 2021 at 9:33 pm #3705134
relatively low risk
Less than 50% chance of dying?Mar 17, 2021 at 10:00 pm #3705138
As in, for the vast majority of my uses, the defects we are talking about are no more likely to cause an issue with the stormworthiness of the shelter than I would expect from normal handling of the shelter; i.e. stuffing it in and out of my pack/stuff sack, laying it on the dirty/gritty ground (I don’t suppose you bed down in soft grass everywhere you go, do you?), random debris interacting with the shelter fabric outdoors.Mar 18, 2021 at 4:11 pm #3705258
From paragraph 2 of Stephen’s original post on this thread:
“I took five readings across the roll. Raw values in PSI are as follow: 1.3, 1.4, 1.1, 1.4,1.4. Average is 1.32 PSI or 928 mmwc. This is a very low value. I did two readings on an aged sample and got an average of 492 mmwc.”
My concern with the above test results was the low HH. Having followed Richard Nisley’s HH tests for many years on BPL, including several that he did at my request, I learned that the HH test result for a new fabric is not very helpful, because after simulated aging, the test results usually drop substantially for nylon and polyester tent fabrics. The artificial aging is done simply by running the test fabrics through a washing machine following a protocol, and represents the expected HH of the fabric after a few weeks in the rain, not to mention the wind that is often present.
A number of BPL members have posted that a minimal waterproof standard is 1500mm. However, a number of mass market tents, like those from Big Agnes, specify 1200mm when their tents are new, prior to any natural aging. And those tents continue to be very popular. However, many of them may be used for more occasional car camping or overnight trips, which might not be challenge to a fabric somewhat below 1500mm HH.
In any case, 928mm HH is quite a drop. And 492mm HH after simulated aging, about one third of the standard that many accept, is not waterproof at all. A nylon or poly tent fabric with that HH will resist rain for a short time if treated with a good water repellent, but will then begin to leak, leaving the occupant of the tent and his or her gear soaked. And possibly hypothermic in colder weather. Raingear, intended to be used in the rain, usually posts an HH several thousand mm higher, and well above the standard used for tent fabric.
For hikers who venture out more often, and can expect to spend anywhere from dozens to hundreds of nights in the rain in a year, multiplied by the number of years the tent lasts, even 1500mm HH is obviously not satisfactory. And the simulated aging protocol at least provides a much better idea of the ability of the fabric to function in a tent canopy.
So while 1500mm HH may be a minimum standard, 3000mm HH is much better, especially if you want the tent to handle a few years of backpacking in climes that receive substantial rainfall. They include the places I usually go, the central Rockies and north country of New England. The southern Pacific Crest and parts of New Mexico may be a different story, but having trekked the JMT, Colorado is a backpacker’s heaven for me, largely because its name Colorado, signifies the well watered wildflowers and forests that contribute to its beauty. Granted, beauty is in the eyes of the beholder, and some folks may prefer to trek in the desert. Each to their own.
But for many, I think, regular heavy rainstorms are part and parcel of backpacking. And that is why I prefer a fabric at a bare minimum of at least 2000mm HH after simulated aging, as I do not want to have to get a new tent almost every year. Indeed the tents I’ve used have lasted many years. Since I make or mod my own tents, a great deal of planning and labor is involved, which amounts to a lot of my time. It is just a hobby, but one acquired for a lifetime, and has served me well with tents that keep me bone dry through all kinds of nasty weather, and don’t wear out in a year or so.
So I hope you can see why for me and many others, a canopy with a 492mm HH would not be an extremely low risk. Indeed, it would not be a risk at all, because it would be unacceptable.
So there is a long version of Roger Caffin’s succinct post above. But either way, the outcome can be a fatal one if gear is not selected or made with informed care.Mar 18, 2021 at 4:43 pm #3705268Tuukka UBPL Member
Are you sure the 1200mm HH is for new fabric? I guess they would mention it if they tested with aged fabric, but I can also see it being omitted to not confuse people. Or, if they do minimal testing and mostly estimate the HH for aged fabric, they wouldn’t want to mention it specifically.Mar 18, 2021 at 4:48 pm #3705270
My blue silnylon tent is still going well and surviving storms. It does not leak. But every few years I pitch it in the backyard on a sunny day and spray it with silicone waterproofing/oil/spray/whatever, then I let the stuff blend into the silicone coating. This does seem to help.
(Note: NOT repeat NOT fluorocarbon DWR! That is INCOMPATIBLE with the silicone polymers.)
I also check the tent poles and ferrules at the start of every season. The very high tensile Easton arrow shafts I use as ferrules can develop splits if mistreated.
CheersMar 18, 2021 at 5:48 pm #3705278
We can agree to disagree all day on this topic I guess. We will all use the fabrics we deem most appropriate. Yes, 3000mm HH is more waterproof than a 1500mm HH, and if you can achieve the higher number with reliable process precision, at a cost and weight penalty you are willing to bear, then go with that. If you are trying to go lighter, or reduce the cost of your shelter (as anyone in the tent business is), then finding the sweet spot matters, and I don’t believe the current testing spot accurately seeks that sweet spot. There is nothing but anecdotal evidence on these forums telling me that 1500mm HH is the sweet spot minimum rating a shelter should have. Big suppliers and cottage suppliers also seemed to have arrived at a number they think is correct, and until someone comes up with a better way of testing that accurately simulates the needs of the product, we will all have to continue to listen to the stories and come up with our own conclusions.Mar 18, 2021 at 9:29 pm #3705310
“We can agree to disagree all day on this topic … ”
Michael, I don’t think so, because I don’t know what I’m disagreeing with. I was trying hard ,to reach you, but am unable to make sense of your rambling discourse. So I’ll have to let it go, at least for now.Mar 19, 2021 at 1:07 pm #3705381Josh JBPL Member
Curious have you tested any dutchware fabrics?Mar 19, 2021 at 1:59 pm #3705392Stephen SeeberBPL Member
I have done at least three. Xenon 1.1 Sil Poly: 6806 new, 1772 aged ; Xenon Wide 1.2 Sil Poly: 3192 new, 1912 aged; Xenon Sil 5300 Sil Poly : 6876 new, 3754 aged.Mar 19, 2021 at 4:16 pm #3705438
This is now guesswork on my part.
I have noticed that some fabric seem to lose more HH when ‘used’ than others. I am not sure why this is so. I suspect that it may be because the coating starts to degrade over the gaps between the threads. In effect, the coating fails to span the gap.
If so, this would depend a lot on the exact nature of the coating: a stiffer coating would be more prone to this. Some of my old Westmark fabric (silnylon) had a quite soft silicone coating, and it seems to have survived very well. Perhaps the new coatings with a higher initial HH are stiffer?
CheersMar 19, 2021 at 5:08 pm #3705448Stephen SeeberBPL Member
It would be nice to get samples of the same fabric from a bunch of different rolls. I have done this to a very limited extent. And I have found variation in HH. I think the HH is a function of the quality of the coating materials, the quality of the coating application, but also, the quality of the underlying weave. Each component will contribute to the tensile strength of the finished product and therefore, its ability to withstand the strain imposed by the HH test or the stresses imposed by wind driven rain or a knee on the floor of a tent. I wonder how much quality control can be achieved as fibers get ever smaller, weaves get ever denser and products get lighter.Mar 19, 2021 at 5:47 pm #3705454
weaves get ever denser
The problem is that the weaves do not always get denser. The thread count or number of threads per inch (tpi) depends entirely on the loom. You can put thinner thread in the loom, but the tpi may stay the same. Thinner threads => bigger holes between the threads.
Can one buy a loom with a variable tpi? I don’t know. The problem would be with the lifters: the things which lift and lower the threads for the weaving.
CheersMar 19, 2021 at 6:15 pm #3705459
I know nothing of how the mechanics of a loom works, even if I understand the basics of the process. What do you mean that the tpi depends entirely on the loom? I imagine the number of threads in warp might be a fixed qty, but as the shuttle moves back and forth compressing the weft down, would that not create higher tpi in weft for a specified tension?Mar 19, 2021 at 7:44 pm #3705466
You are right to some extent.
The way the shuttle compresses the latest weft thread against the older ones can increase the tpi on the weft, but then you have an unbalanced warp/weft ratio. Weavers try to avoid that because it makes for strange behaviour on the bias. That is not good.
CheersJun 9, 2021 at 10:54 am #3717910
On March 18, 2021, I posted in part on this thread as follows:
“… the fact is that the fabric I bought did not test waterproof by any standard, and that is something I’ll need to take up with the seller. It may take some time, but I’ll let readers know how it goes.”
To follow up on that, please note that RBTR furnished me with a replacement order; however, the additional material received from RBTR yielded approximately the same results as before in further testing by the OP, Stephen Seeber. So I will be looking for another material, since I want to get back to making a tent, not hassling about quality issues. With that said, I will leave this matter, hopefully for good.
I wish to thank Stephen Seeber for his kind assistance by testing of this fabric. Without his help, and with the help of Richard Nisley on earlier fabrics, I would not be able to pursue MYOG tent projects with any assurance that the time and effort is well spent. Thank you also to readers for your patience. Sam F.
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