UV and Silnylon?

[toughfeet]

Hey gang.

Just had someone ask me if the silnylon I recently bought for making a tent was "uv stabilised" as he had had two silnylon tents, one of which failed in half the time of the other due to uv damage. Is this a thing? Any tips as to where to get "uv stabilised" silnylon if there is such a thing? Anywhere I should avoid?

Cheers!
Toughfeet.

[simonm]

I have sourced, and sell, a 30 denier ripstop nylon with silicone/urethane blend coating that is listed by the manufacturer as having UV inhibitors. I can't vouch for it's long term UV performance as yet though as I am just finishing up my tarp.

http://www.tiergear.com.au/11/online-sh ... 30-Denier/

[toughfeet]

Thanks Simon. Does that imply that you can't get uv inhibited silnylon without the urethane?

[Moondog55]

Here's a question then
Will the Solarproof from Nikwax adhere to silnylon??

[simonm]

Thanks Simon. Does that imply that you can't get uv inhibited silnylon without the urethane?

I don't know the answer to that, I will see what I can find out from my suppliers.

[simonm]

Here's a question then
Will the Solarproof from Nikwax adhere to silnylon??

I don't know the answer to that one either.

We all know the impacts of UV on lightweight gear. Personally regardless of what it is I try to minimise my gears exposure to UV as much as possible.

[simonm]

From some quick reading - silicone coating is generally more UV stable than a PU coating hence why you probably see UV inhibitors in PU coatings.

[Strider]

PU is only coated on the back side too, isn't it?

[simonm]

PU is only coated on the back side too, isn't it?

Usually I think that it the case if its used on its own, though there are some coatings which are blends and they are usually coated on both sides.

Not all coatings are created equal either.

[toughfeet]

Thanks for the responses. I do tend to pack down camp and reset each day so not much daylight hitting my tent. It is still something I want to be cautious of though. Let us know if your suppliers tell you anything else Simon!

[simonm]

From one of my suppliers:

You are absolutely correct about the UV inhibitors, their exact cause is to "inhibit" the UV Rays from deteriorating the fabric quickly. It's not to say it will never effect it, the process just takes a lot longer with UV inhibitors. Also, the 100% Silicone fabric actually already does have the UV inhibitors in it, not sure why we haven't listed it that way but I double checked with the owner and it was a thumbs up.

[sunnyape]

Just had someone ask me if the silnylon I recently bought for making a tent was "uv stabilised" as he had had two silnylon tents, one of which failed in half the time of the other due to uv damage. Is this a thing? Any tips as to where to get "uv stabilised" silnylon if there is such a thing? Anywhere I should avoid?

Just to explain further, 'UV stabilised' does not infer 'UV proof' just 'UV resistant'. All silicon impregnated nylons will gradually deteriorate over time due to sunlight exposure, even with a stabiliser added. The biggest factor in UV degredation is actually the colour, as the pigmentation will increase or decrease the spectral interferance and thus absorb or reflect more UV light.

Think of the light spectrum using ROYGIBV. Ultra Violet is in the high frequency range, so if you want a tent that lasts longest against UV, choose one that is violet and is reflecting the most high frequency light waves. If you want a tent that burns out quickly, go for red that is absorbing the most high frequency (Infra Red is low frequency). Next the lighter the colour the less light being absorbed, so that infers more UV reflected.

In summary, avoid dark red, orange and yellow. Go for light green or blue (who would want a light violet tent URGGGH). Grey is all colours at once, so it is in the middle of the range in terms of UV absorption.... but it makes for a tent that disappears well in the bush

[Orion]

The biggest factor in UV degredation is actually the colour, as the pigmentation will increase or decrease the spectral interferance and thus absorb or reflect more UV light.

Think of the light spectrum using ROYGIBV. Ultra Violet is in the high frequency range, so if you want a tent that lasts longest against UV, choose one that is violet and is reflecting the most high frequency light waves. If you want a tent that burns out quickly, go for red that is absorbing the most high frequency (Infra Red is low frequency).

I thought that UV stabilizers worked by absorbing the UV light.
Why would the reflectivity in the visible spectrum matter?

[Moondog55]

G'Day Orion, I would hazard a guess the UV reflection is related to reflection in the visible band to some degree and I guess also that will apply to IR as well
I'm not sure that sunnyape has it right tho, my experience is that the silver aluminium exterior coating is the longest lasting [ I think it may also be the heaviest and that may be more important] red seems to bleach quicker but I'm not informed on the relationship between bleaching and fabric deterioration

[simonm]

Some interesting links - one specific to UV the other abrasion.

http://www.researchgate.net/publication ... Protection

http://www.outdoorequipmentsupplier.com/Thesis_web.pdf

[Orion]

Simon, thanks for the links.

That first one has to do with the protection factor of a fabric; that is, the degree to which it prevent transmission of UV to your skin. It doesn't address UV degradation properties.

Wikipedia mentions UV stabilization briefly:
http://en.wikipedia.org/wiki/UV_Stabilizers_in_plastics
http://en.wikipedia.org/wiki/UV_degradation#Prevention

Here's another discussion from a company called Craftech:
http://info.craftechind.com/blog/bid/38 ... bilization

They list three primary methods of UV stabilization: absorbers; quenchers; and amine light stabilizers. The first absorbs the UV directly and the other two try to clean up the damage caused when the polymer absorbs the radiation. They don't mention reflecting the incoming light as a strategy.

[simonm]

Perhaps I should have read my first link a little more closely .

[sunnyape]

I thought that UV stabilizers worked by absorbing the UV light. Why would the reflectivity in the visible spectrum matter?

Yes, stabilisers work by abosrbing or reflecting UV frequency radiation then disappating the energy or converting into another form IE heat, light etc. The dyes inside the nylon do exactly the same thing; they take light (energy) at a particular frequency and manipluate it into something your eyes can perceive as a specific colour. Sure, the visible light spectrum is below UV, but the violet part of it is closer whereas the red part is furthest.

Remember, when you see a colour, your eyes are perceing what has been reflected, but that means the rest of the spectrum has to be absorbed. Here is a very generalised way of thinking of it:
When you see something that is red, that means orange, green, blue, indigo and violet are being absorbed. It is the absorption of the violet biased (high frequency) energies that causes the molecules to move faster and it to 'burn out' faster.
When you see something that is violet, that means red, orange, green, blue and indigo are being absorbed. It is the absorption of the red biased (low frequency) energies that causes the molcules to move slower and it to 'burn out' slower.

Have a look at all the boats in the harbour. See how the canvas sail covers are usually blue or sometimes green? Blue resists UV degredation the longset.
Look at all the old posters in shop windows. See how they all have a blue tint? That is because the Magenta ink has faded fastest, followed by the Yellow with the Cyan being the last to go.

[Moondog55]

That explanation I understand and is that why the cheapest tents always seem to be blue?
But total reflection i:e silver /aluminium coatings would seem to be the most stable

[simonm]

Thanks Sunnyape, that makes a lot of sense.

[sunnyape]

That explanation I understand and is that why the cheapest tents always seem to be blue?
But total reflection i:e silver /aluminium coatings would seem to be the most stable

Yes, aboslutely. If you could make silnlyon that was totally reflective (a mirror), not only would it last the longest, but it would be the coolest to sleep in.

As a side conversation, originally, the first woven nylon material was called F111 / ripstop and was developed by the aerospace industry as a replacement for silk for the round parachutes that brought the early capsules back to earth. The sports of parachuting, hangliding, ballooning etc then used it to make collapsible flying things. However, F111 had a degree of porosity that let the air slowly leak out, so the things had to be quite large. When a silicon coating was adding, that filled in the gaps between the weave to make it air tight and it became know as 'zero porosity F111' and resulted in higher performance flying things for the same surface area.

In the late 90s, when siliconised nylon was first coming to the market, there were some initial batches made that were 'silver' or somewhat reflective; it sort of looked like dull aluminium foil. When it was new, it looked fanstastic and I remember seeing a few parachutes and hangliders being made with it. However, whatever they were adding to create that reflective characteristic made it less flexible and heavier. The material looked terrible after you had scrunched it up and then un-packed it repeatedly.

[Orion]

Yes, stabilisers work by abosrbing or reflecting UV frequency radiation then disappating the energy or converting into another form IE heat, light etc.

As I posted before, I haven't been able to find any mention of reflection as a means of UV stabilization. The mechanisms I've seen discussed repeatedly are absorption, quenching and free-radical scavenging. Could you point me to a link that discusses reflection as a strategy for UV stabilization?

Sure, the visible light spectrum is below UV, but the violet part of it is closer whereas the red part is furthest.

But are you sure the reflectance is always similar in the invisible UV range? If a dye absorbs red light at 700nm and reflects blue light at 450nm why are you so certain it will reflect UV light at 350nm?

For that matter, wouldn't absorption in the UV by a dye be a good thing for the fabric? The whole point of UV absorbers is to catch the photons so that the chromophores in the polymer aren't excited by them.

Have a look at all the boats in the harbour. See how the canvas sail covers are usually blue or sometimes green? Blue resists UV degredation the longset.

That could be. Or maybe it's a fashion decision, I don't know. I did find a website that sells sun covers in a variety of colors, including red. They come with a 10 year UV degradation warranty regardless of the color. But silnylon could be different.

It would be an interesting question to ask Hilleberg: Does their red siliconized nylon fabric that they use in their tents have a significantly shorter life than their green fabric?

[Orion]

But total reflection i:e silver /aluminium coatings would seem to be the most stable

Aluminum maybe. But polished silver has a minimum in its reflectance spectra at around 330nm, near the UVA/UVB boundary. So while it makes for a great mirror in the visible and IR region silver is a poor mirror for UV. If it's a thin enough film it actually becomes somewhat transparent in UV.

[sunnyape]

As I posted before, I haven't been able to find any mention of reflection as a means of UV stabilization.

Titanium dioxide is used as a stabilising agent in thermoplastics. It works via reflection.

But are you sure the reflectance is always similar in the invisible UV range? If a dye absorbs red light at 700nm and reflects blue light at 450nm why are you so certain it will reflect UV light at 350nm?

Nope, not sure at all.

For that matter, wouldn't absorption in the UV by a dye be a good thing for the fabric?

It depends on what that absoption is translated into. If the dye fluoresces, then that's fantastic. If the dye just gets hot, that's not so good.

The whole point of UV absorbers is to catch the photons so that the chromophores in the polymer aren't excited by them.

I have no knowledge of how chromophores in polymers work or are excited.

It would be an interesting question to ask Hilleberg: Does their red siliconized nylon fabric that they use in their tents have a significantly shorter life than their green fabric?

It wouldn't be hard to get some dark red and light blue silnylon and conduct a side-by-side exposure test.

[Orion]

Titanium dioxide is used as a stabilising agent in thermoplastics. It works via reflection.

TiO2 is a UV light absorber.

It depends on what that absoption is translated into. If the dye fluoresces, then that's fantastic. If the dye just gets hot, that's not so good.

The UV absorbers I read about convert the energy into heat. Like TiO2, for example.

It wouldn't be hard to get some dark red and light blue silnylon and conduct a side-by-side exposure test.

I have a number of scraps of silnylon (as well as PU coated and uncoated nylon) in a variety of colors. The silnylon colors I have include red, yellow, sky blue, royal blue, navy blue, purple and black. I'd be willing to test them if it wasn't too difficult, but I'm really not sure how to do it. Any suggestion?

[icefest]

Maybe there is some more recent research re TiO2, but in 2003 there was still no consensus re MoA of UV protection:
http://ningpan.net/publications/51-100/88%20polymer.pdf

[Orion]

Maybe there is some more recent research re TiO2, but in 2003 there was still no consensus re MoA of UV protection:
http://ningpan.net/publications/51-100/88%20polymer.pdf

It's rarely all or nothing, but the authors of that paper were pretty clear about what they found.
Look at the reflectance spectra that they measured.

Or what they had to say at the end:

CONCLUSIONS
1. As the experimental results show, regardless of
the particle sizes, TiO2 clearly absorbs UV radi-
ation, which can be explained by the solid band
theory. This is different from the previous view
that submicron-TiO2 absorbs little UV. Also,
TiO2 works as a UV-blocking additive mainly
through UV absorption, and the scattering and
reflection mechanisms are significant only in the
band where TiO2 has either weak or nonabsorp-
tion, although TiO2 has a higher refractive index
than that of most other semiconductors.

[icefest]

Thanks orion, I was going to have a more in depth read tonight, but i think the matters settled.

[Moondog55]

Making me think that when I get around to making my next batch of silicon waterproofing for old tents and tarps i should use a coloured silicon, it seems any colour would offer some extra protection but perhaps the white would offer the most. I did not see silver silicon at Bunnings in a neutral cure but I did see some in the acid cure section