DIY HH Tester

Hi all you knowledgeable people,

thanks so much for this insightful thread, I have learned a lot already.

I am currently trying to decide on a material for my next project, and would like to ask you:

Does the lower weave density of Shield mean it is mechanically weaker than other competing products? If so, how much? Meaning, is the difference significant in real life?

I feel I have to outweigh through-misting, general waterproofness, and the longevity of the waterproofness (in which Shield seems to perform best) against mechanical properties (which I'm not yet quite sure about regarding Shield).

Another question I have been thinking about is: If rip stop nylon has the tendency to leak along the stronger threads (if I'm getting one of the earlier posts in this thread right), how strong a case would you say that is for using non rip stop nylon instead? I assume the loss in rip stopping ability is too high a price to pay, but would like to hear what you think about it since you know a lot more than me obviously.

If you can shed some light on these questions, I would be grateful…

Richie

Richie,

I didn't measure the mechanical performance of shield but, comparing it to the weave density of most other silnylons via micrograph, it is similar. Although Shield was the best silnylon that I had tested to date, the same coating, with a higher density weave would yield an even better product. I assumed that like the competition in the M90, M55, and M50 market segments, even better alternatives will be available at some point in the near future.

That would be really nice if they put silicone on one of those lighter nylons

The 30d of standard silnylon is way stronger than necesary. For a regular tarp in normal conditions I don't think it comes anywhere near tearing.

> If rip stop nylon has the tendency to leak along the stronger threads, how strong a case
> would you say that is for using non rip stop nylon instead? I assume the loss in rip stopping
> ability is too high a price to pay,
First of all, I will claim straight out that the use of ripstop fabric for UL gear is totally UNNECESSARY. There have been very, VERY few reports of fabric failure in the field with even the lightest of fabrics. If you get into a situation where the fabric is going to rip, I really don't believe that the ripstop threads will save you. OK, let's leave out those cases where the gear failure is due to sheer bumbling 'user error'.

So why does everyone use ripstop? Two reasons: marketing spin and inertia. OK, maybe a third reason: ignorance due to a lack of testing. The market asks for ripstop so the coating companies supply ripstop. It's time we changed that.

So, if you can get a plain-weave fabric instead with a similar coating, go for it (after HH testing of course).

Cheers

> After that post, Roger Caffin, Paul Nanian (Thru-hiker), and I jointly collaborated on
> additional Shield testing.

This project is not dead; it's just waiting in the queue to recover from my hard disk crash and loss of data.

Cheers

I'll take the fabric that adds protection against user error, thank you very much. Tired people will make mistakes.

"I'll take the fabric that adds protection against user error, thank you very much. Tired people will make mistakes."

Yeah, you want enough margin to allow for errors you might make, but you don't want extra margin, because it's too heavy.

If you made a tent out of 4 ounce nylon you could dive into the tent and have your dog do this also without hurting the tent

You could design it so the tent stakes would pull out just before the fabric would rip, or something like that, and it would be even better engineered

What works for one person might not work for another person…

Hi again,

Roger, I agree with you – for ultralight use. Our situation is slightly different from that scenario though, so I'm not convinced just yet unless there are hard numbers somewhere. If there aren't, I may have to just go with rip-stop for this project and application.

This is why:

"If you made a tent out of 4 ounce nylon you could dive into the tent and have your dog do this also without hurting the tent"

Well, that's kind of what our shelter will have to live with sometimes. In our case, it's not a dog but two very energetic preschool children. Normally they are really good with gear, but when everyone is tired or over excited, stuff happens. The same goes for those rare but hectic moments where we pitch in horizontal rain-thunderstorms and the like, where it will be us, the parents, not beeing super careful with the gear.

In addition, we occasionally have very high winds, to the point where walking becomes difficult for an adult.

From experience, I can clearly say that the Ray-Way sil-nylon is up to all that, as long as it is sewn right. So I'm pretty sure 4 ounce nylon is really not needed even for that. But I have a feeling I would prefer to keep the rip stop in the sil-nylon for our application.

We always go light, but we are not on an ultralight mission, and top priority is gear that requires minimum attention, time and energy from us while out there, while providing a high level of reliability even under less than ideal use – because that does happen in real life, especially with children and on trips that go beyond a simple overnighter.

An action that is tough on gear that you could call a "bumbling user error" on a nice sunny day very quickly becomes an action that is extremely hard to avoid under seriously tough conditions, and that's exactly when I can not afford to have a shelter fail on us.

I have the impression that sometimes, people who go ultralight tend to not think about what actually happens when for example their shelter goes to shreds in a "totally unexpected" blizzard. Of course, there are places on earth where conditions are more predictable, and there are those where that is less the case. Still, stuff happens, and I really don't mind whether I carry 12 or 15 kilograms of gear. Each to their own, of course.

On very long trips I found out that I can happily walk with up to 35 kilograms, and that's not for bragging, quite the opposite: I weigh 70 kilograms myself and am neither a super fit athlete nor a couch potatoe – I think most people can carry a lot more than they think. I am in no way debating that less weight is better for many reasons, and even increases safety on trips as well – that's absolutely correct! But there is a limit to that, and if you go below that, the problems that that can cause in those rare but very tough situations are not worth saving yet another few hundred grams.

Just something to think about, not telling anyone how to go by any means, and I'm very thankful for the ultralight movement because it is continuously contributing to making gear and gear systems better.

Now, back to choosing a fabric… :-)

Happy trails!

Richie

Hi Ricahrd

> I have the impression that sometimes, people who go ultralight tend to not think about what
> actually happens when for example their shelter goes to shreds in a "totally unexpected" blizzard.
I think that might be a bit off the mark here. You should consider subscribing and reading some of our articles, including "When Things Go Wrong" (winter, snow, winds over 100 kph) and "Storm Resistance of Ultralight Shelters: Part 1, Introduction " (self explanatory).

Cheers

silnylon can withstand blizzard

dogs and kids and don't mind extra weight? might be better off with 4 oz nylon

Roger, I'm sorry if you or anyone else felt offended.

I wasn't referring to BPL or anyone here in the forums, nor was I criticising the ultralight approach in general; far from it. Rather, I was referring to some people we have met offline in the mountains, who were so lightly equipped that they most definitely would not have been able to look after themselves should the weather have turned.

I know that most people who go ultralight think very carefully about how they do things and what they take. I still stand by my view though that some people do develop a too single minded approach in that regard, ignoring the possible consequences of bad choices.

That happens with everything; there are always some people who do things recklessly, be it driving a car or going ultralight. I just wanted to point out that because going ultralight is such a desirable goal, it can happen that one forgets to keep other important things balanced.

Another things is that the more you push the concept of ultralight, the more you rely on not making any mistakes – and people frequently make mistakes, no matter how skilled and knowledgeable they are, especially in tough situation. We are human. It happens. That's why I like to allow a little room for error, that's all.

Cheers,

Richie

If you would like to have a piece of Ray Jardine's sil-nylon for testing, let me know, I can mail you a bit.

Would be curious myself how it compares to Shield, for example, especially since I have had great experiences with Ray's material myself (more about that here: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=60573).

Richie

Jerry, I know, from own experience :-)

Although we don't want to go ultralight, 4 oz is a little too heavy for us.

We don't have dogs, and from experience I can say that Ray's (probably around 2.2 oz) sil-nylon is tough enough for our kids.

The only thing where a wee little more would be good is regarding stretching in very high winds (also see the other thread, see link in my previous post).

I'm thinking maybe around 2.5 oz or so would be ideal for my taste, but of course it depends on a lot more than just that number.

Richie

Richard,
Ray's site states that his silnylon is in the same weight range as other 30 D silnylons – 1.3-1.4oz. He claims to have a proprietary treatment to make it more waterproof, but whatever the merits of that, it would not increase its strength.

It sounds like you have run into gram weenies who are placing themselves at risk.
Roger is not even remotely one of those. Just take a look at his tents on the Bushwalking.org.au FAQ site and do read "When Things Go Wrong," on this one.

If you want heavier canopy materials, look at the material used by Appy Trails, or the material in the Chinook tarps. The latter is coated polyester that won't sag like silnylon. The former – do not recall. But polyesters tend to be less strong than nylons. And if you want to go broke, there are sturdier cubens in the 1-2 oz range, a number of which are sold in smaller quantities by Zpacks.

My only gripe is that none of the silnylons sold by Ray Jardine or Thru-Hiker are in the earth-tone – green range. Lightheart Gear uses a better quality silnylon in its imports, but that is not the one it sells as yardgoods. Most of the silnylons currently available are much inferior as far as water proofing goes. Read Richard's tests on this site.

Roger's posts suggest that current EPA regs in the USA have required firms here to discontinue the more WP silnylon treatments. Whatever the reason, the HH testers don't lie (although they could be mistaken, as any scientific measurement can be). I think that if you buy the cheap stuff, you will eventually be disappointed. It will sag a lot, and its waterproofness will diminish fairly quickly with use. It will probably tear more easily also.

Lance, would you make another HH tester for (what) price?  I live in an apartment and don’t have the means to do this but I can see paying you to do so for what, double your material cost?   I believe in one’s labor being rewarded fairly (not enormously, just fairly).  I don’t know how much labor you’d be putting into doing so.  Thanks for your consideration.

Roleigh,

This thread motivated me to build one of these, albeit with some different materials and design.  The biggest challenge was getting the piece above the fabric clamped tightly enough to stop any leakage at the seal.  Since the physics involved are very basic, and with some kind responses from Editor Roger Caffin, that part was not a problem.  The next biggest problem was designing one that would not get water all over the place and take forever just to test one piece of fabric. Roger came up with an approach to that which looks much like a cider press.  For me, it became one of those works in progress that go on forever, and  I confess that it was never put to full use because the posts from Richard Nisley are much more useful in every imaginable way.  Thanks to him, gear and fabric merchants are specifying HH much more often, and they are accurate or at least in the ball park more often as well.  AFAIK, he is still accepting one foot square swatches for testing.  I’ve learned from his BPL posts a wealth of into about fabrics to use in MYOG without becoming a slave to a ‘forever’ project.

Hi,

I made my own a year ago, and it works pretty well from 250 to 4000mm.

I posted photos and results here.

Materials (wood and PVC) are quite inexpensive, but it took some adjustments seal it properly. Manometer came from a cheap sphygmomanometer.

Roleigh, i’m afraid i really don’t have time to make an other one, but maybe this design might help you or someone else ?

Xavier

Roliegh,

Look up a local carpenter.  They should be able to help you.  The only thing in this project that requires anything more than a drill and a pair of scissors is cutting the 3/4″ plywood.  A carpenter should be able to give you the pieces of plywood cut to spec for less than $50.  If you don’t have a drill, the carpenter will be able to knock those out too.  Everything except the pressure cuff can be purchased at your local hardware store.  If it is an old school shop they may be willing to cut the plywood for you too!

Here is a blood pressure cuff for $10 off of Amazon prime: https://www.amazon.com/Manual-Blood-Pressure-Child-Black/dp/B000I58RFW

If you can’t assemble these pieces, you are probably going to have a hard time running the test.

You don’t need a manometer either, although it might be convenient of course. Try hanging up (vertical!) about 3 – 4 m of 1/4″ beverage tubing with the tester connected at the bottom. When you have a water column of 3 m above the fabric, you will be getting a very big bulge!!!

This was only 2 m of water column.

Cheers

Xavier,

The research on tear strength and HH with realistic aging simulation is very impressive and useful.

I also checked out your website. Your tipis are beautiful.

The durability of the mixed sil/pu coatings on RBTR’s 15 (membrane) and 20d silpoly fabrics appears to be pretty good (HH does not drop below 1,000mm after two months of exposure). Nevertheless, after several months of use it is reasonable to assume that the HH will drop below a ‘safe’ level.

At that point, with traditional silnylon (no pu mixed with the silicone), we could re-coat the fabric with a mixture of silicone and liquid solvent (mineral spirt, etc.). Do you have any experience that would help us predict whether this type of re-coating mixture would adhere to sil/pu coatings.

Thank you Stumphges

I’m not sure that this mixed sil/pu coating on both sides is very different from the regular sil coatings. I can’t feel any difference when i tear, cut, sew or bond between RBTR’s coatings and Extremtextil’s silnylons. Silnet sticks the same on both fabrics.

I never recoated RBTR’s fabrics with a mixture of sil/mineral spirit, but i daily use silicone to bond reinforcements and it works very well, with no sign of aging. I think that the mixture of sil/mineral spirit would adhere the same on these fabrics.

(Just to avoid reader’s misunderstanding : i’m talking about fabrics from RBTR coated on BOTH sides with their “sil/pu” coating, NOT about their fabrics with sil on one side and PU on the other one)

Hi Xavier,

Thanks very much for your informative reply. That’s what I was hoping to hear:)

Regarding your concluding clarification, the UL community definitely needs to get some clear naming scheme for the various fabric types now on the scene:

1. Nylon coated on both sides with 100% silicone (or what we’ve historically assumed to be same), i.e. Silnylon
2. Nylon coated on both sides with a mixture of silicone & polyurethane (PU) (see RBTR’s 20d “silnylon”)
3. Nylon coated on outside surface with 100% silicone (or what we’ve historically assumed to be same) and inner surface with polyurethane coating.
4. Nylon coated on outside with mixture of silicone & polyurethane and on the inside with PU coating.
5. Polyester coated on both sides with 100% silicone (not sure if anyone is selling this)
6. Polyester coated on both sides with a mixture of silicone & polyurethane (see RBTR’s 15d & 20d “silpoly”)
7. Polyester coated on outside surface with 100% silicone and inner surface with polyurethane coating (see RBTR’s “silpoly PU 4000” fabrics.
8. Polyester coated on outside with a mixture of silicone & polyurethane and on the inside with PU coating.

Clearly, there is the problem of mixing up the poly- of polyester and polyurethane, for starters.

This outline ignores the various types of non-silicone coatings used on the inside of fabrics that are referred to colloquially and collectively as “polyurethane: or “PU.” I don’t understand these variations, although some here, like Roger C., do. Edit: it would appear from the Polyurethane wiki that the polyurethane coatings used on the inside of some of the polyester and nylon fabrics is of the polyether variety, due to its hydrolysis resistance and flexibility at low temperature. Interestingly, polyether PU also has poor abrasion resistance.

Anyone have any idea how to refer to these fabrics without the necessity of two-sentence clarifications?

Chuckle.
I did ask a rep from a major corp who supply the silicone polymer for more details once. The guy asked which of the 100 different variations was I interested in. Um. In fact, he more or less confirmed that each coating mill might have their own formulation. And that is just for silicone!

Silicone on one side and PU on the other – well-known. Silicone and PU mixed together – that is a bit newer, and techie details seem to be lacking. Help anyone?

Cheers

I remember reading that Sil/PU mix avoided VOCs during the manufacturing process, but i’m not sure and i can’t find the reference anymore.

Hi Xavier

I am not saying you are wrong, but I have some technical doubts. If either silicone polymer or PU polymer separately involve VOCs, I can’t see why mixing the two polymers would eliminate the VOCs.

It is always possible that the source hadn’t a clue or was just spinning. But if you do find the source, please tell!

Cheers