UKC

Looking to buy a new tent and dont want suggestions thanks but can't decide between polyester or nylon fly?

Nylon is stronger but then when have you ever seen a polyester fly rip?

Polyester is more UV stable (a bit) but then when have you ever seen a nylon fly fail?

The PU and Silicon treatment is the waterproof part of the fly so does polyester/nylon make any difference?

I've always bought nylon before as most good brands use nylon but do people realy think it makes a difference? Concensus of oppinion is?

In reply to epik:



nylon is better than polyester because it stretches less when wet, which matters for two reasons.

one is that if the flysheet sags through being wet it can affect the strength of the tent.

the other - more important - reason is that if the fabric stretches, over time this leads the waterproof pu-layer to delaminate from the outer fabric, reducing the life of the tent and its waterproof qualities.

you should aim for a tent with a tent that has a nylon flysheet that is double silicone coated - ie, is proofed with a layer of silicone on both sides of the fabric.

this stops the fabric fibres getting wet in the first place, and it also gives better UV protection.

i'm such a geek...

actually i got mixed up. polyester streches less than nylon when wet i think.

but with double silicone coating this doesn't matter, and nylon is stronger, meaning less weight.

In reply to Lightweight:

so between Sili/PU nylon or Sili/PU polyester polyester is better in you oppinion but 2xSili nylon is better over all!

Strength thing; is polyester realy that much weaker to make a difference in a say fully geodesic or semi tent? for example do the UK TNF tents realy hold up that much better than US versions?

In reply to epik:

no-one else got any insight into which to choose or does everyone aggree that poly is better unless its double sili?

In reply to epik:

As Lightweight eventually remembered, nylon absorbs quite a lot of water into the fibre, and elongates as it does so. Result: saggy tent in the morning or after rain. A polyester fly will remain taut better.

I'd say that the strongest weight-for-weight is double silicone polymer coated nylon (not that I have any figures for tear strength to hand...). It's interesting to note that Macpac used to use polyester, but their UV30 fabric is now double-Si 30-denier nylon. Of course, this could simply be the result of moving their production to Vietnam... The silicone coating adds UV resistance.

In reply to captain paranoia: One of the climbing magazines (climb?) had an article on tents and included advantages/disadvantages of different types of fly.

I will go and try and find it...

In reply to Oli: Gear Section of CLimb:

Nylon is very strong and robust, giving strong, lightweight flysheets. Main problem is that it sags if material becomes wet. Also untreated nylon is not very UV resistant.

Polyester-> not as strong, so may need thicker material. better UV resistance, but tend to lose their colour quicker.

Silicon elastomer coated on nylon (both sides) is apparently best but expensive

In reply to Oli:

Yeah i saw the article and i have always held fast that double sili nylon (like my last tent) is best and people like crux say this also. i do wonder if andy is tainted by the fact he is mates with crux? as say always a double sili person but beginning to wonder, like i say when have you ever had a fly fail and not sure i can be bothered with the whole seam sealing again!

In reply to captain paranoia:

many brands use PU backed in the US due to fire retardancy regulations but all seam to say double sili is best so maybe they are right. maybe i should go with what i've always believed. i just wonder why its best?

Guess you get less condensation on a double sili nylon! wonder if double sili is better for UV than polyester with sili one side and PU other sie? so many choices!

In reply to captain paranoia:

macpac may just be to do with what factories can actually achieve and cost of fabrics! though they will have to use PU backed in US. Do you often have tear strength data to hand?

p.s. was it you i was talking to about single skin tents aswell? finally got one to test!

In reply to Lightweight:

Seperate point what sort of price should i expect to pay for a dogs danglies 2man/4season mountain tent?

Last tent i bought was in 97 so competition wasn't as strong so what sort of price if i shop around? £300? £400?

In reply to epik:

When you coat a fabric, you usually reduce its tear strength, because you prevent the fibres of the weave from moving over each other, which is one way in which the fabric adapts to loads. Thus, the coated fabric tears like a piece of paper.

Silicone coatings seem to be much lighter than PU, so maybe the fibres can still move over each other. Or maybe they stretch better than PU.

Silicone is naturally water repellent, whereas a PU nylon will need a DWR treatment on the face to prevent water absorption.

I'm speculating, I'm afraid...

In reply to captain paranoia:

many modern tent fabrics have sil one side and PU other though so no DWR needed. i think you may be on the right track but i do wonder why double sili is better than PU at a micro level! though could it be something to do with....

PU is hydrophilic but not gas permeable so is a wet membrane and absorbs water vapour into water molecules in order to pass it out so on a nylon it would still stretch as the nylon would still get wet. whereas double sili is gas perm so vapour passes through rather than actual liquid water so doesnt stretch and is stronger and maybe the sili helps with UV. Could this be the reason? does this even make sense? would it still get wet even though its vapour rather than liquid?

Double sili is def the best.

If you're interested, Robert Saunders wrote a pamphlet on this and other issues (like why you shouldn't bar-tack stitch tent fabric as the number of needle holes in a specific area weakends it, etc).

Perhaps he still has copies for sale.

http://www.robertsaunders.co.uk/