Help with how to sew a tricky seam

[Sam Farrington]

Geoff, after reading the newer posts, please give me another try to be helpful with this.  Assuming your tent is closest to the Turner tent shown first in your original post, I agree with Roger Caffin’s response that a bucket floor might be the way to go.  The walls of a bucket floor are  around 5-7 inches high, and attached to the insides of the tent walls in whatever way best fits the inside of the tent. Water will flow down the outside of the tent walls to the ground, and the “bucket” will prevent it from flowing onto the tent floor.  But avoid Warmlite’s floor if it sticks out where it can get wet. It is up to you whether to bond the bucket walls to the inside of the tent, or sew them, or just connect them with velcro strips or patches or other joinery so the floor can more easily be replaced if needed.

But with the 40 denier walls, I get the impression that you want the tent to bear up under the worst weather, so are looking for a very strong wall to floor attachment.  Using Roger’s instructions, I bonded a sample of silicone coated fabric to a second sample using alcohol to clean the samples, then coating them with the Permatex Windshield and Glass sealer noted by Randy, and clamped the bond for at least 3 days.  There are many Permatex adhesives, but this one is sold by Amazon, NAPA and other companies, so the right one is readily obtainable (Amazon puts this adhesive near the end of its long list of Permatex offerings.)  I found the bond was very strong, much stronger than Wacker Elastosil E43 (wrong number?), but the Permatex bonded fabric could still be pulled apart, and torn apart when I tried this with DCF (wanted to see the guts of the DCF).  Roger said the Permatex is the best silicone adhesive for bonding sil fabrics, and having been a physicist in the fabric market, he ought to know.  And agree that the small amount of polyurethane in some silcoats is not a bar to bonding; otherwise there would have been a hue and cry raised by now over all the seam sealants sold for silcoated fabrics.

Typically, widths of fabric rolls are 58″: so with a 5″ high bucket wall, you would have over a 45″ wide floor with some extra to sew or bond folded edges.  If 45″ would not be wide enough; then yes, another seam in the body of the floor might be needed, as has been suggested.  If the floor is not square in shape, that should be no problem so long as the floor is fashioned to fit within the tent walls.

Being envious of DCF tents, but not able to afford them, in order to keep the weight low, I will be using fabrics of lower denier, around 20D, and harvested from an extremely strong but light Yama tarp to make a  floor.  But by all means, do it your way, as Frank Sinatra said.

You seem to have a better grasp of gizmos that join fabrics together than I do; so there may very well be a clip of some kind that would hold the floor solidly in place at the corners and sides.  With my first tarp tent, velcro patches did the job, but the real problem was the overhang was not adequate to keep out precipitation, especially in the middle of winter at Little Rock Pond in Vermont.  My buddies filled up the open shelter, so I got stuck with my do-it-yourself creation, and dam near froze to death, not to mention that we got threatened by some guys who reminded us of the Deliverance movie about down river canoeing in the South. But a good samaritan with a snowmobile and attached trailer gave us and our ladies a ride back to the trailhead, which cheered us up.

Agree with your approach using the inverted V to hold up a cover over the door.  The gizmos used by Lightheart Gear to join two trek poles to hold up their tents could make the door even wider than the V.  Used a set up like that at one time and as you say, it was a joy to have dinner out of the rain.  But would not try it in bear county, especially grizzly bear country, which I have now forsworn.

I hope this is at least a little more helpful.

[Geoff Caplan]

Moab Randy –

I picked up the basting tape from my local sewing shop. She thought it was 3M, but looking at it there’s no branding so I can’t be sure.

I rub the tape with the back of a spoon to improve the bond.

It’s not in any way a firm hold – it’s only a slight tack. But when I use my mini-clips to double-secure the seam, it’s enough to hold everything in place. The needle does gum up after a while, but if you wipe it regularly it’s a non-issue. I think Roger recommends dipping the needle in washing up liquid, but I haven’t found the need.

I’m doing my testing with Hilleberg Kerlon offcuts – they used to sell random bags, but I don’t see this on their site these days, sadly. The Kerlon is triple-coated and super-smooth, so my thinking is that if I can pull of a nice seam it should be easier on most other fabrics.

And once the seam is sewn, my testing suggests that the adhesive helps prevent water ingress. I’ll still seam seal, but anything that helps is welcome!

Also, it seems to help prevent elongation of the seam, which will presumably help reduce flapping in a storm.

I’ve just ordered some Pellon EZ-Steam II tape to see if it does a better job. It has an adhesive on both sides to help with accurate positioning, and then you fuse it with a warm iron. There’s an old video by a guy from ProLite and he got good results with ripstop – though he doesn’t say if it’s coated. There are plenty of alternatives to try from Dritz and others but the Pellon is generally well reviewed.

https://www.youtube.com/watch?v=Ne2J01h1tZ0

Hope that’s helpful!

[Geoff Caplan]

Sam

Yes – I’ve dithered quite a bit over whether to simply attach the floor directly to the bottom of the fly WarmLite style, or whether to suspend it from the walls like the ProTrail, the DuoMid and Roger’s legendary tunnel.

The pros of the direct seam are:

• Simplicity of construction, especially around the doors
• Simplicity of erection because the floor determines the shape.
• This also means you don’t need pegs or shock-cord to tension the floor.
• No way for driven dust and snow to reach the sleeping area.
• No way for vapour evaporating off the grass or bog to reach the sleeping area.

Mike Turner tells me that it worked perfectly well for his Torside bivy tent pictured above, and of course Stephenson’s have been doing this for decades.

The only disadvantage I can see is that you don’t get side-venting through the suspended mesh. But I’m designing the whole tent around strong thru-venting so I hope I’ll get away with that. It’s the main unknown but it seems like a decent bet. Mike Turner found that condensation in the Torside was manageable with the ends open, even though it’s tiny. My design is a fair bit bigger so should perform a bit better on that front.

Another disadvantage of the suspended floor is that in some designs like the ProTrail and the DuoMid you see regular stories of the mesh poking out under the fly so water pours directly into the bathtub and people wake up floating on their airbeds. This can happen with a less than perfect pitch, or with fabric sagging, or if you roll against the wall while asleep. Something I could live without…

I’m planning quite a complex double door to give me full control over venting and insect protection. Integrating this with a suspended floor would be a bit of a nightmare, so in many ways the decision is a no-brainer because I have to keep within my limited skills!

Thanks for the heads-up on the Permatex vs the Wacker. As you say, if Roger prefers the Permatex it’s surely the way to go.

[Jerry Adams]

I’ve always wondered if “bathtub floor” means it fills with water : )

[Geoff Caplan]

Moab Randy –

Quick follow-up to our discussion on basting tape.

I had just taped up a new practice seam and pressed it flat with a cool iron when I was interrupted by a long Skype call.

When I went back to the job a couple of hours later, the adhesion was much stronger – it didn’t need clips to hold it in place. The combination of heat and time seems to cure the adhesive.

I also experimented with basting the overlap and then both of the folds as you prepare the full flat fell – I’d only tried the initial overlap till now. It works well and means that there’s 0% chance of any fabric slipping. All you have to do is sew a straight seam using the edge of the final fold as a guide. Turn over and repeat.

Far too time-consuming for commercial work, but for MYOG it reduces the chances of wasting expensive fabric. I’ve tried forcing water through the seam at pressure, with no penetration. I’ll seal for safety, but it does seem to produce a very water-resistant result.

[Roger Caffin]

You can also get silicone transfer tape from various sources: pure adhesive and no carrier film. It is what I use in many places. It really does bond to the silnylon fabric but does not affect the mechanical properties of the fabric (the way a carrier film would)..

However, two caveats: it is more expensive that the common or garden tapes which use an acrylic adhesive. That partly reflects the volume of production. Of course, the cost may not matter for an MYOG project.

The second point is that silicone-silicone bonding is SLOW. This is a matter of chemistry. You are advised (by mfr) to give it 72 hours for full strength, although a few hours gets you a long way. That matches what Geoff found.

Even if you don’t give a silicone tape ‘long enough’, it will cure in place in the seam later on and can be very good at sealing the needle holes when used as Geoff describes.

Cheers

[Moab Randy]

OK, Geoff, interesting. But you don’t know what brand it is?

I’ve tried the Pellon Easy-Steam without heat and it wouldn’t adhere at all, so I don’t know how I’d stick it in place until I can add heat. . . .

[Geoff Caplan]

This guy’s doing something similar, but with silicone slurry. Even more hassle than my approach, but he gets an impressive result:

https://ivovanmontfort.blogspot.com/2013/01/verwerken-van-silnylon-stof.html

The tape I tried yesterday is unbranded from a UK eBay seller who assured me it was super-sticky. It was advertised as High Tack Sailmaker’s Basting Tape. eBay’s purchase history service is down right now so I can’t access the vendor – I’ll post again if I can get you more info.

[Sam Farrington]

For the present, was not able to evaluate strength of the basting tapes mentioned above when used with a silcoated fabric.  Recall that Roger has posted about 3M silicone tapes, but do not recall the specifics.  Am fascinated with the suggestions that basting tapes are becoming a trend in tent construction.

So is it worth it to hunt for, obtain and test the best basting tapes on the market that bond silcoated fabrics?  Based on my experiences with McMaster-Carr, expect them to be quite expensive.  Also, silcoated fabrics are usually more elastic, and despite the boom on DCF and other laminate fabrics, there is very little elasticity.  Whether you deem elasticity in high regard probably depends on your experiences with it.  My own bent is strongly in favor of it in tents, because it provides the highest wind resistance, and eliminates flapping, distortion and worse in well designed tents.

So I’d attach a bucket floor to a tent wall by just sewing them together along the walls in such a way that the threads are covered over by the fabric as much as possible, with the exposed threads out of sight and seam sealed during construction.  As soon as time permits, will create and post a diagram.

The two tent shapes mentioned are a 2 sided tapered A-Frame with a cat-cut roof seam and end beaks; and a 4 sided pyramid with cat-cut wall seams.  Both shapes create walls that slant to the ground at an angle that makes for some wasted space along the walls, but not as much as the Skurka designs, which are very popular.  The catch is that the outer tent walls must be designed so that their bottoms are held securely in place by the peg points to keep the bucket floor in place.

Flexible poles like those pictured in the earlier post also add to  elasticity and stability; but have tried to stick to the old standards that have been discussed here.

[Geoff Caplan]

Another data point on basting tape.

I just dropped in on Aiguille Alpine Equipment here in the Lake District. The proprietor, Adrian Moore, has a storied history as an alpinist and has been making gear since the ’70s. They still manufacture everything in-house, and Adrian gave me a very generous tour of his workshop.

https://www.aiguillealpine.co.uk/

I picked up a lot of tips, but on basting tape he simply uses the standard 3M sailmaker’s product.

He reinforced my own view that you’re not looking for a strong bond – simply enough tack to prevent the fabric from moving when combined with pinning or clipping.

So I think it’s about having realistic expectations about what the tape can offer. But it’s interesting that they use it for certain jobs even though he has highly skilled machinists on top quality industrial machines (he says it takes 2 years to train up new staff!).

I’m increasingly convinced that basting tape can be very helpful when used the right way.

One of the main takeaways was his passionate support for high quality Cordura as a pack material compared to the trendy laminates, if you want robustness and long life. But that’s a debate for another time…

[Jerry Adams]

“One of the main takeaways was his passionate support for high quality Cordura as a pack material compared to the trendy laminates, if you want robustness and long life.”

that makes sense

or, if you want to go ultralight with a penalty on durability, 200D fabric

[Geoff Caplan]

He sells a 1000, a 500 and a 230 (ish). He advises using 1000 textured for the body and 500 smooth against the back and for pads and belts.

Given that you’re only using around 1.5 yards for the body, I don’t know why people obsess about using light fabrics given the marginal savings. You’re talking about 80 grams – or the weight of a shot of cappuccino.

With a heavier fabric you can use it as a seat in the middle of a bog, throw it down on granite slabs, sling it in plane hold, scramble, bushwhack and generally abuse it to your heart’s content and it won’t flinch. And no need for fancy reinforcements to protect the seams.

But that’s veering wildly off topic…

[Jerry Adams]

Yeah, I agree, pack uses small amount of fabric so not that important to use super light fabric

But, I’ve never had a problem with 200D fabric.

I have had laminated fabric delaminate.  Once, I used 1.9 oz/yd2 silnylon but that eventually ripped – thats too light.

[Sam Farrington]

Geoff et al.  Sounds like you’re going with bonding, so no reason for diagram(s) on sewing techniques that I mentioned earlier.  Good Luck!

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