How do I repair this Cuben Fiber Shelter?

One more issue over the top of the hiking pole of the outer shelter.

It's also coming apart where I have circled in red.

The shelter, it's very similar to a DuoMid Shelter. I only received the shelter today, Custom made to suite me. But I'm concerned with what I see happening, . It's made from .71oz Olive Green Cuben.

ZPacks sells repair patches made of cuben hybrid. You could try sticking them to the back (they're self-adhesive) then restitching the tie-out through the cuben hybrid.

Thanks William. I will look into the patches.

If I pick out the stitching, place tape over Cuben Fiber and restitch the tie-out, sounds like an easy repair.
Not sure what to do with the top of shelter, Could I just stick this patch over the stitching on the top?

"… My Custom Made Cuben Shelter turned up in the post today, Pitched out the backyard, I noticed the Cuben Fiber around the stitching was coming apart. How can this be repaired?"

OUCH!

Was it like this straight out of the package? Do you have any recourse from the supplier of your shelter?

Party On,

Newton

Yeh, I noticed it had started to come apart when I taken it out of it's stuff sack.
Windy day here today, 44 kph winds, with the strong winds It started to come apart further, so I grabbed some Duct Tape as a temporary repair but it didn't work.

Supplier will repair it, but I'm not sure he knows how to best repair, I thought I should do some investigation myself. he has never worked with Cuben to this degree his learning. I don't think he realised it had to be taped on all joins and seams.
With the rest of the shelter the joins in the Cuben are first sewed than he taped over the top, not sure what tape was used, but it's an inch wide and clear tape, by the looks of it.

Apart from the taping, his done a pretty good job on the shelter.

It is a flawed design. There is way too much stress being put on a stitched seam of cuben. I doubt you will be able to repair this and have any confidence that it will ever be able to withstand any abusive weather. Sorry, I'm usually an optimist.

Yikes. Pretty sure that violates most of the rules of working with cuben. Some ideas for salvaging it:

Good tape on the ridgeline. 3m 9485 with a strip of cuben on one side was the tape of choice around here for a long time…haven't heard of anything else recently that's widely available.

The tieouts are extra tricky because that webbing is so close to the "reinforecement" blowout stitching. I'd totally remove that webbing/tieout and get some of the hybrid cuben patches from zpacks for the reinforcements. Maybe even reinforce both sides since it's already compromised. DON'T SEW THEM TO THE MAIN BODY. Let the adhesive do the work. For the actual tieouts, only stitch through the rolled hem (you might even take out the stitching on the hem and re-roll it after you've added the hybrid reinforcements for some extra layers).

edit: The part you circled is tricky too. Maybe another patch plus a healthy amount of seam grip on the other side????

Simple answer, you cannot. Last year there was a good discussion of cuben and seams. The "officially sanctioned" methode was to use adhesive tape, then sew it. I suspect that you may still need to seal the threads with silicone caulk (diluted,) though no one has mentioned this.

You CANNOT expect to sew cuben like you would silnylon. It looks like your tarp came from someone without the knowledge of dealing with plastic films(cuben)vs fabric(slinylon.) The damage to the material done by a needle, which shows up as what you are seeing, is about the same as "nicking" a piece of plastic for opening a package. By applying the adhesive tape first, this will reinforce every stitch through the plastic. ALL NEEDLE HOLES NEED THIS REINFORCEMENT. Yes, it gumms up the needle if it gets warm from stitching too fast through flat/rolled seams. Generally, a little alcohol will clean the needle…

Repairing the damage already done is likely not possible at home…'nuff said. I would suggest simply cutting about 1/8" beyond the seams and starting over. You will loose about 2" in width and length. Reinfoce the tieouts with another piece of cuben about 2" beyond any stretching…enough to get new loops and adhesive tape over the loops. I believe the recomended technique was to use arced reinforcements. At the pole tip, perhaps three layers of bonded/sewn cuben. Sorry, but the damage you are seeing will get worse. Also, elastic bands work well to reduce wind hammer on the tarp (and stakes.) Perhaps a 8" piece of guban properly applied along the perimiter and peaks could repair it. Even the hem's need to be taped with glue. Sorry for the bad news…but investing more in quick fixes will never repair it enough to be reliable. Duct tape works as a temperary measure, but this is strictly temperary.

I suggest that you have soneone fix it that is familiar with cuben fiber, MLD, ZPacks, etc. I would NOT send it back to your vendor. He obviously doesn't know how to work with CF. Good luck!

As a service to the BPL community, it would be nice to know who made the shelter so that other hikers can avoid the same problem!

Stop payment. (Hopefully you paid with a credit card.)
Send it back "Signature Required".

There is so much wrong …

Thanks for the advice. Greatly appreciated. Im from Australia. Shelter is Custom made in Australia.

This is a major repair, I thought it might have been a simple repair.

I think the cuben hybrid patch ZPacks sell is the solution, I like brendans suggestion of using two layers, one on both sides and sandwiching the cuben in between the patch. If this method is used does the damaged area still need to be cut away?

Not sure about that top area, that looks to be a difficult repair.

What about the rest of the seam lines on the shelter, they have been sewn together and tape placed over on the inside of the shelter over the seams, theres no tape over the stitching on the outside. Theres also some stitched seams near the top thats not taped, i can see there just starting to come apart similar to the images above. No where near as bad, but I can see it will eventually completly fail with time.

Hi Phillip

Those pictures are so bad it isn't funny. Basically, you should rescind the deal. The goods are not fit for purpose (Trade Practices Act).

My first thought was that this tarp has seen a LOT of bad weather and been severely stressed, before you got it. The damage around the sewing holes indicates that a LOT of force has been applied. The Cuban material is shredding.

The more vexed question is whether the design can be repaired to be reliable. I have severe doubts. The damage suggests that it just is not going to work. You simply cannot sew Cuban like that and expect it take the loads: it just does not work that way. I suspect the mfr did not know how to handle Cuban.

Sorry, but.
Cheers

Hi Roger.

Your suggestion is the most logical approach to take. To be fair I will alway's be concerned with it, even after repairs, it's most important that this shelter is of sound condition and will withstand storms. As it's to be used in Tasmanian Conditions and on the Larapinta Trail next winter. So a reliable shelter could be the difference between life and death in those conditions, and up here in Queensland our summer storms are extreme, so the shelter will need to handle those conditions.

I will send the shelter back, I want one of those MLD DuoMid"s.

I think it might be repairable, but by the time you add new tie outs, and bond new patches you might as well get a new tarp.

In my opinion your tarp is a total loss, i'd sell it to someone and maybe they can make you some stuff sucks.

In my opinion sewing cuben is basically like perforations on a sheet of white paper, you know the technique that's used to make it easy to rip out of a notepad.

Phillip,
You have done quite a service in bringing this to our attention, as a heads up to other folks working with Cuben. Much more informative than the pic that Ryan posted a couple times. Hope you will take Roger's and others' similar advice.

Taping is fine, but in a lot of tests I've found that it has very little peel strength, and may not relieve stresses on the stitching created by the conditions you describe. Cubic Technologies uses a proprietary heat-based process to get the PET, or Mylar, to adhere well. Tape is a poor substitute.

So I've concluded that I will not put Cuben into a sewn seam without folding over the edge going into the seam into a hem, inserting a strip of sub 1 oz PU treated Dupont 6.6 nylon, like Porcher Skytex 27, and bonding the sandwiched hem with Hysol 2-part urethane low viscosity adhesive. This is not a a totally peel strength bond, but is the best adhesive I've found for this after testing a couple dozen of them, and appreciate the help of Lawson and others in posting about the Hysol.

I imagine clamping will be necessary also, making the process daunting enough that I've decided for now at least to use the silnylon Thru-Hiker sells for the next MYOG shelter. It will add almost 4 ounces over Cuben to the shelter, have some sag as the temp drops, and I don't like TH's color options (I went for a Coyote brown canopy for stealth, and a orangy "sun" yellow floor for not losing stuff), but tests by a number of contributors to this forum showed it to be far superior in water resistance, and I've found that its sag factor is much reduced also, to about the same extent as some of the softer paraglider fabrics I've tested that are treated to reduce sag but are less water resistant. The Dupont 6.6 nylon is also very strong for its weight. So I think the almost 4 extra ounces for the "Shield" silnylon is worth every gram. Who knows, maybe I'll get to love a brown tent. Silnylon is thin enough that plenty of light will come through, and the orangy yellow floor will brighten things up.

The good news is that the shelter is probably salvageable. However, since you're asking advice on how to do it. It's a pretty good bet you're not capable of doing a permanent repair. As Roger suggested send the shelter back to its maker. No one should be in the business of making and selling CF shelters until they've made a number for themselves and used them in some pretty harsh conditions. It takes a lot of time, money and failures to overcome the inherent issues with Cuben Fiber.

Hopefully you'll get your money back and the designer can use it to experiment on new manufacturing techniques before trying to sell any more.

This is Judy from LightHeart Gear (under my husbands log in) – Yes, the tent is repairable, the tie out webbing probably needs to be removed first, and patches glued over the ripped area, the webbing needs to be re-sewn with some sort of support –
use regular contact cement, tape off the areas you plan to patch, smear some contact cement on the area and on the patch, wait for them to dry, stick together and roll over it with a wallpaper roller – use pressure. then put the webbing back, put a piece of grosgrain ribbon or something similar on the back side of the tent and sew back in place. Then put some cuben tape over the needle holes. – someone mentioned 'clamping it' – I have no idea what this is, just get a good roller and roll over it after putting the 2 parts together. I have a wide rubber roller (from scrap booking section of craft stores) and a hard plastic wallpaper roller that I use. If I can glue a seam – that's all I do, if it has to be sewn, and most of my tents do have to be sewn, then they get sewn. Areas that are under very high stress get heavier cordura nylon patches to support the seams.

I sew cuben all the time (wish I didn't) but any seam that gets any stress will have to be taped, especially if it's cuben to cuben. generally if I sew cuben to mesh or zippers it doesn't always get reinforced, but sometimes it does. This is why I hate working iwth cuben, it is VERY labor intensive. Sew a seam, tape it, cut a pice, glue a patch on it before sewing… it takes twice as long to make a cuben tent as it does to make a silnylon one. I know I've been threatening for a long time to quit working with cuben, but somehow, my stock just keeps getting replenished, and I keep getting orders. Some day…

Along the ridge line, I would probably just tape it to reinforce the area, it may need a patch glued on , but probably not. One of the reasons it's pulling apart is that it's not a lapped seam – this was a plain seam sewn on a single needle machine and then folded over – so the one side wehre it is pulling apart does not have the reinforcement that the other side of the seam has. Occasionally this type of seam is needed, but a true lapped seam is much stronger. – it requires a sewing machine that has 2 needles, 2 bobbins and special folders.

I'm curious, if this is the outside of the tent, how is it seam seled? This is why I have never been an advocate of using silnet as some have on cuben, the holes do stretch, and silnet does not bond with cuben. I tape all outside seams to seam seal and reinforce.

Also, since this is brand new – return it!

Yeah, I agree with most that Marc had to say. The upper seam still needs reinforcing, somehow. A full lapped seam would have been better…

The apparent stress on the seams cannot be from a light breeze. The loops, pole pocket and ridge line are all damaged. Remember that the spectra fibers are stronger than the plastic. So where thay have anchored behind some stitiching, they will stress the fulm for several inches away from the joint.

Anyway, unless you are very interested in saving 1-2 ounces, all the patches, glue and reinforcements also cost weight. The extra material you will need will cost money. The time spent (perhaps a day or two of solid effort) to get the thing straightened out would be better spent in simply making one yourself… I know you decided to return it. Good decision. I do not think you would be saving any weight over a silnylon version by the time you tried to repair it.

For Cuben fiber, it is extremely strong as long as there are no punctures. The minute there is a puncture, it loses it's strength almost completely and will tear from that point in a straight line outward somewhere. To fix that, you would have to remove the stitching, cut away any dammaged material, then re-sew taping the areas that are being sewn so the holes caused by the stitching are not stressed in a way where they would pull apart.

The fact that the manufacturer of your product was not aware of this would lead me to believe that any other craftmanship done on the unit could also be compromised in a way that could cause a catastrophic failure while in the mountains which given the weather scenario you are in could be a very bad situation.

"I will send the shelter back, I want one of those MLD DuoMid"s."

Definitely the best plan…I wouldn't even mess with taping/stitching, etc. as this will just add weight, look horrible, and the tent will just fail somewhere else anyway by the looks of the construction!