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.
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
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.
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.
Franco wrote:There is silnylon and there is silnylon...
Anything from 500mm to 5000mm waterhead so don't judge all silnylons from one test or two.
Years ago I took this photo . That silnylon was rated at around 1500mm.
I don't know how many gallons of water I put in there but I think you get the idea.( no it wasn't dripping hours after....)
( I found my comments about that photo, I had 16 litres of water in there)
telemarktim wrote:My reason for posting the leaky photo was to point out this issue to Orion who had suggested this HH test when he was negative about my use of non-waterproof polyester fabric for my tent. My polyester tent does not leak rain drops and has none of the above listed problems of a similar tent made of silnylon. For me, this is a major improvement for backpacking functionality of a MYOG tent. Tim
Orion wrote:telemarktim wrote:My reason for posting the leaky photo was to point out this issue to Orion who had suggested this HH test when he was negative about my use of non-waterproof polyester fabric for my tent. My polyester tent does not leak rain drops and has none of the above listed problems of a similar tent made of silnylon. For me, this is a major improvement for backpacking functionality of a MYOG tent. Tim
It's well known that polyester has the advantage over nylon in terms of water absorption and consequent stretch. Polyester is weaker than nylon, so there is that tradeoff to consider, depending on the context. The real question here is whether an uncoated polyester fabric is sufficient for wet conditions. Your anecdotal testimonials are insufficient to establish this.
What fabric, specifically, are you using?
telemarktim wrote:If you looked the boring detail in my full post you will see that the tent made from polyester has stayed dry during days of heavy rain. I will leave others with more open minds to judge its sufficiency for wet conditions for themselves.
Orion wrote:telemarktim wrote:If you looked the boring detail in my full post you will see that the tent made from polyester has stayed dry during days of heavy rain. I will leave others with more open minds to judge its sufficiency for wet conditions for themselves.
That is offensive that you are implying that my mind is not open, particularly when in my first post I said that it was quite possible that you could achieve some degree of water resistance. You report that a particular fabric works for you. The question is: what are the limits?
I asked about the specific fabric. I had forgotten that in your original post you said it was salvaged from an old umbrella. So we don't have details. Fabrics are complicated: weave type, yarn weight, thread density, calendaring, DWR, etc. Surely you are not making the case that all uncoated polyester fabrics are sufficiently water resistant for this application.
Next time I buy some fabric I'll include an order for a yard of generic uncoated polyester and fashion a model of a simple pyramid tent. As a control I'll make an identical one out of the cheap silnylon I use sometimes and then give them both 5-10 minutes spray with the garden hose.
1. Keep all content friendly, polite and clean. 'Flaming', hostility, insults, obscenity, abuse and personal attacks are not permitted. Offending content may result in official warnings or bannings (or other moderation - see moderation guidelines below). In particular:
Debate should be about the topic under discussion and not about any person(s) (involved in the discussion or otherwise).
Content should be suitable for a family audience.
Within reason, content should not be offensive to other members, guests or third parties (within reason - sometimes offence is a problem of the offendee rather than, or as well as, the offender).
Attempts to bypass the word censor are not permitted.
Users browsing this forum: No registered users and 4 guests