Help with making a polyester tent

Discussion about making bushwalking-related equipment.

Help with making a polyester tent

Postby telemarktim » Sun 04 Jul, 2021 2:22 pm

Hi All, I am looking for help with making my pyramid or bell tents with un-coated and breathing polyester woven fabric (umbrella fabric) and would appreciate suggestions from those who have 'gone before me'.

Sorry if there is an existing topic and I have just not been able to search properly for it. Please point me to such a post if I have missed it.

I am able to make strong, light and comfortable tents with silnylon (even if the stitching of the slippery silnylon is a bit ugly). They are 'walk-in tents for two and a tent stove and gear storage when the 300mm bell wall is deployed (as in the first photo below). They become a bomb-proof cramped stooping-walk-in tent for the survival of two under adverse weather conditions (as in the second photo). The only negative issue is the dreaded condensation inside on some nights. When it combines with buffeting winds, it is like having fine misty rain inside.

I should also add that I have no formal floor sewn into my tents (I use separate light groundsheets instead.) so that they can easily accommodate a tiny tent stove. They do have generous breeze/bug/snake/snow skirts around the whole base, so if any water should wick down the surface, it would not be an issue. For more details please see my website post on the tents:
https://timtinker.com/ultralight-tent/

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I have done a little side by side test of scale model pyramid tents that were pitched for about a week at home on my green moist lawn, where water transpiration was guaranteed. (sorry I can’t find the photo). Both had no floor, one was made of silnylon and the other of un-coated polyester (fashioned from an old cheap but colourful umbrella).

They both shed the rain well with no apparent leaks. Each morning, the silnylon tent was always coated with much condensation inside and the polyester tent was always dry. Even when I put a large dinner plate of water at the bottom of the polyester tent, there still was no condensation.

My question is: Can polyester without waterproof coating or silicone rubber impregnation provide a waterproof shelter without condensation issues? I would treat the seams/stitches with diluted acetic cure RTV silicone rubber to make polyester/cotton sewing thread repel water.

I would like to hear from others about their experience with using un-coated polyester for single skin tents. Tim
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Re: Help with making a polyester tent

Postby Bill P » Thu 29 Jul, 2021 10:00 pm

Hi Tim,

I have no direct experience of uncoated polyester tents. I sometimes bring prospective diy fabrics up to my mouth and blow/suck through them to test their permeability and suitability for my intended purpose. Just take care in the fancier stores!. You could probably do a more scientific pressure column test. I am building a skin on frame kayak with an uncoated polyester skin but that will be coated after heating shrinking on the boat.
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Re: Help with making a polyester tent

Postby Orion » Fri 30 Jul, 2021 11:08 am

It sounds like crazy question, can a fabric without waterproof coating be waterproof. But it may well be the case that the DWR coating will serve to repel rain, up to a point. And only as long as the DWR lasts.

You don't even need to get too scientific about it. Take a big square of fabric, gather it so that you have a kind of bag, then fill that "bag" with water. Observe.
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Re: Help with making a polyester tent

Postby telemarktim » Tue 03 Aug, 2021 11:09 am

Orion wrote:It sounds like crazy question, can a fabric without waterproof coating be waterproof. But it may well be the case that the DWR coating will serve to repel rain, up to a point. And only as long as the DWR lasts.

You don't even need to get too scientific about it. Take a big square of fabric, gather it so that you have a kind of bag, then fill that "bag" with water. Observe.



Hi Orion, Most innovations start with apparently crazy questions (according to those who are stuck in the rut). That is how we have been able to move out of the cave to tents and houses! There is no such thing as a stupid question it is usually the answer to the question that is demonstrably stupid.

I have not proposed anything 'scientific' in support of my tent idea. On the contrary, I described a simple side by side test of scale mode tent made of umbrella fabric or silnylon and observed what happens. This was not so different to your suggestion of making a 'bag' of the fabric and filling it with water. "observe'. That is exactly what I would do if I was making a water bag, but I was wanting to make a water shedding device called a tent.
Tim



For thousands of years, unproofed cotton fabrics and similar have been used for comfortable and dry tents way before the invention of synthetic fabrics.On the other hand, your suggested 'scientific' test of a kind of bag of may be appropriate for testing a fabric
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Re: Help with making a polyester tent

Postby Moondog55 » Tue 03 Aug, 2021 11:48 am

Not waterproof but unproofed fabric can shed water.
Parachutes are very LW and the old style were relatively porous compared to modern stuff and could be used to make highly water resistant emergency tents in the tipi style.
It was a combination of steep walls and at least 2 layers of fabric well separated that allowed such structures to work.
Ditto early tents
Not sure that helps tho
Ve are too soon old und too late schmart
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Re: Help with making a polyester tent

Postby telemarktim » Tue 03 Aug, 2021 6:44 pm

Moondog55 wrote:Not waterproof but unproofed fabric can shed water.
Parachutes are very LW and the old style were relatively porous compared to modern stuff and could be used to make highly water resistant emergency tents in the tipi style.
It was a combination of steep walls and at least 2 layers of fabric well separated that allowed such structures to work.
Ditto early tents
Not sure that helps tho


Thanks Moodog, Very constructive. I will be trying it as a single skin tent to see how it goes. Tim
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Re: Help with making a polyester tent

Postby Orion » Tue 03 Aug, 2021 9:14 pm

For sure there are stupid questions. I'm not saying your idea has no merit, simply that you have little hope of achieving a high degree of waterproofness. You already know the fabric sheds rain to a certain extent. My non-scientific suggestion was simply an easy way to test the limits.

My partner's pack cover wetted through during a recent storm. Back home it appeared to shed water just fine. But the bag test showed that under stress it leaked like a sieve. It was still fine for light rain but worthless in more serious weather. We replaced it.
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Re: Help with making a polyester tent

Postby telemarktim » Thu 30 Sep, 2021 7:07 pm

Orion wrote:For sure there are stupid questions. I'm not saying your idea has no merit, simply that you have little hope of achieving a high degree of waterproofness. You already know the fabric sheds rain to a certain extent. My non-scientific suggestion was simply an easy way to test the limits.

My partner's pack cover wetted through during a recent storm. Back home it appeared to shed water just fine. But the bag test showed that under stress it leaked like a sieve. It was still fine for light rain but worthless in more serious weather. We replaced it.


Hi Orion and others, I have now done quite a bit of backyard testing of the polyester tent including side-by-side testing with an equivalent silnylon one and it has performed without fault so far:
No rain leakage on long wet nights,
Much less condensation than with an equivalent silnylon tent,
Worked well on two sub zero nights up on the Bogong High Plains, froze inside and out,
Survived very strong and gusty winds,
Packs up as small as the silnylon tent,
Did not go saggy like the silnylon tent and needed no pitch adjustment over two days and nights
Weighs about 100g more than the silnylon tent, and
Dries very much more quickly compared with silnylon.

For more details of the tent testing, please see:
https://timtinker.com/diy-breathing-polyester-tent-for-backpacking/

Image
Image

Here is a video tour during heavy rain:
[youtube]v=W47QauLAXgs[/youtube]

Tim
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