Surely there's a better alternative to PU?

[James Donohoe]

Hi all, I would like to ask a question that has been bugging me for a long time- Why don’t we see heavy woven nylon fabrics (eg. ‘Cordura’ / texturised nylon 500 or 1000 D) coated or impregnated with silicone? I have bought 1000 D nylon from many sources and all of their PU coatings are really poor. Seeing silicone treatments of lighter nylons, I can’t help thinking it could make a really durable, superior alternative to PU on texturised nylon. Am I mistaken? Is there such a product that is readily available? Cordura is still an excellent pack fabric for my needs but think it could be loads better with Si. Any ideas or thoughts?

[Tipi Walter]

Good question.  I mean, silnylon is a silicone treatment onto and into nylon and  . . . uh . . . cordura is nylon . . . so . . .

[Chris R]

Maybe it has something to do with the denier of the thread used to weave the fabric? Or the air texturing?

i believe that some Cordura uses an acrylic coating.

You could always use 420d Robic instead.

[R]

Silicone costs more and by the time you’re at such a heavy fabric your probably not concerned with the impact on strength the coating has. Also, silicone doesn’t accept fire retardant chemicals limiting which states manufactured goods can be sold in.

When impact on strength isn’t a concern, I think PE coating is the next thing to look for.

Treasure trove of nerdy goodness: https://www.slingfin.com/blogs/the-beta/fabric-coatings-101-pu-vs-pe-vs-silicone

[Roger Caffin]

@Rene
Some points to ponder:

By and large, fire retardants (FRs) do NOT work as claimed (and never have), but they are all toxic. The FDA keeps banning the latest FR, so the mfrs simply change the molecule slightly to evade the ban. In Europe, where the authorities are a shade more intelligent about such things, all those FRs are banned based on the general formula. They are TOXIC.
The support for the FRs comes 100% from the FR (mfrs) Alliance; the opposition comes from the medical world.

The old PU coating absorbed water and went gooey. It has been replaced with TPU, which is quite different. It does not go gooey, and it has a good HH rating.

PE has been hovering, but it has not (so far) demonstrated enough improvement. It might one day, maybe.

I suggest you simply ignore the State regs which mandate FRs. Trans-ship if necessary.

Cheers

[Tipi Walter]

One reason I went with Hillebergs was to get away from flame retardant tents.  It’s sad I spent almost 30 years backpacking with and living in outgassing, toxic and stinky tents.

[R]

I was just suggesting FR laws in some US states may be hindering adoption of incompatible coatings such as silicon.

I forgot about TPU. Don’t know much about the chemistry or impact on strength. diypackraft.com offers a selection by the yard.  Their 1000D weighs 22osy, $40yd.

[James Donohoe]

Wow, the whole FR topic is pretty interesting actually, but I still don’t understand why Si impregnated light nylons are widespread, but not the heavy stuff. Maybe Chris R’s suggestion is true- that the denier or textured fibres makes it impractical? You’re right, Rene, that the matter of strength due to coating is probably irrelevant with a heavyweight nylon, but surely the durable and elastic nature of Si helps maintain the fabric’s stability over time? Roger I didn’t know that TPUs are a significant improvement over the old PU- perhaps I have never seen it. Do the usual suppliers to hobbyists (DIY, Seattle Fabrics, OWF, Rockywoods, Extremtextil etc) mostly sell PU or TPU coated texturised nylons? Where do I find the good stuff :-) ?

[Chris R]

I have read in a reputable publication that the whole FR coating requirement came about due to shadow lobby organization set up by the tobacco industry. Pressure was growing to stop smoking after a number of fires linked to smoking in bed. The shadow group persuaded legislators that adding fire retardants would be better/easier than stopping folk from smoking.

[Roger Caffin]

A lot of the ‘blow-up’ started with a series in the Chicago Tribune, back in 2012 or earlier. They blew the lid off the whole FR fraud. You can find the series in the paper: search on “Tribune Watchdog Playing with Fire”. I think the URL is http://media.apps.chicagotribune.com/flames/index.html

Btw – they won a Pulitzer Prize for their work.

To quote their lead article:

The average American baby is born with 10 fingers, 10 toes and the highest recorded levels of flame retardants among infants in the world. The toxic chemicals are present in nearly every home, packed into couches, chairs and many other products. Two powerful industries — Big Tobacco and chemical manufacturers — waged deceptive campaigns that led to the proliferation of these chemicals, which don’t even work as promised.

They have a LOT more to say. Going on from there:

Dr. David Heimbach knows how to tell a story.
Before California lawmakers last year, the noted burn surgeon drew gasps from the crowd as he described a 7-week-old baby girl who was burned in a fire started by a candle while she lay on a pillow that lacked flame retardant chemicals.

“Now this is a tiny little person, no bigger than my Italian greyhound at home,” said Heimbach, gesturing to approximate the baby’s size. “Half of her body was severely burned. She ultimately died after about three weeks of pain and misery in the hospital.”

Heimbach’s passionate testimony about the baby’s death made the long-term health concerns about flame retardants voiced by doctors, environmentalists and even firefighters sound abstract and petty.

But there was a problem with his testimony: It wasn’t true.
Records show there was no dangerous pillow or candle fire. The baby he described didn’t exist.

Neither did the 9-week-old patient who Heimbach told California legislators died in a candle fire in 2009. Nor did the 6-week-old patient who he told Alaska lawmakers was fatally burned in her crib in 2010.

Heimbach is not just a prominent burn doctor. He is a star witness for the manufacturers of flame retardants.
His testimony, the Tribune found, is part of a decades-long campaign of deception that has loaded the furniture and electronics in American homes with pounds of toxic chemicals linked to cancer, neurological deficits, developmental problems and impaired fertility.

The tactics started with Big Tobacco, which wanted to shift focus away from cigarettes as the cause of fire deaths, and continued as chemical companies worked to preserve a lucrative market for their products, according to a Tribune review of thousands of government, scientific and internal industry documents.

These powerful industries distorted science in ways that overstated the benefits of the chemicals, created a phony consumer watchdog group that stoked the public’s fear of fire and helped organize and steer an association of top fire officials that spent more than a decade campaigning for their cause.

Today, scientists know that some flame retardants escape from household products and settle in dust. That’s why toddlers, who play on the floor and put things in their mouths, generally have far higher levels of these chemicals in their bodies than their parents.

Blood levels of certain widely used flame retardants doubled in adults every two to five years between 1970 and 2004. More recent studies show levels haven’t declined in the U.S. even though some of the chemicals have been pulled from the market. A typical American baby is born with the highest recorded concentrations of flame retardants among infants in the world.

People might be willing to accept the health risks if the flame retardants packed into sofas and easy chairs worked as promised. But they don’t.

The chemical industry often points to a government study from the 1980s as proof that flame retardants save lives. But the study’s lead author, Vytenis Babrauskas, said in an interview that the industry has grossly distorted his findings and that the amount of retardants used in household furniture doesn’t work.

“The fire just laughs at it,” he said.

Other government scientists subsequently found that the flame retardants in household furniture don’t protect consumers from fire in any meaningful way.

The U.S. Environmental Protection Agency, meanwhile, has allowed generation after generation of flame retardants onto the market and into American homes without thoroughly assessing the health risks. The EPA even promoted one chemical mixture as a safe, eco-friendly flame retardant despite grave concerns from its own scientists about potential hazards to humans and wildlife.

Since the 1970s manufacturers have repeatedly withdrawn flame retardants amid health concerns. Some have been banned by a United Nations treaty that seeks to eliminate the worst chemicals in the world.

Chemtura Corp. and Albemarle Corp., the two biggest U.S. manufacturers of flame retardants, say their products are safe and effective, arguing that they have been extensively evaluated by government agencies here and in Europe.

“Flame retardants provide an essential tool to enable manufacturers of products to meet the fire safety codes and standards necessary to protect life and property in a modern world,” John Gustavsen, a Chemtura spokesman, said in a written statement.

His company, Gustavsen said, strongly disagrees with the main findings of the Tribune’s investigation.

Heimbach, the burn doctor, has regularly supported the industry’s position that flame retardants save lives. But he now acknowledges the stories he told lawmakers about victims were not always factual.

He told the Tribune his testimony in California was “an anecdotal story rather than anything which I would say was absolutely true under oath, because I wasn’t under oath.”

Heimbach, a retired Seattle doctor and former president of the American Burn Association, also said his anecdotes were not about different children but about the same infant. But records and interviews show that the baby Heimbach said he had in mind when testifying didn’t die as he described and that flame retardants were not a factor.

After the Tribune confronted chemical executives with Heimbach’s questionable testimony, he offered, through his lawyer, another explanation for why his stories didn’t add up: He intentionally changed the facts to protect patient privacy.

Yet the most crucial parts of his testimony — the cause of the fire and the lack of flame retardants — had nothing to do with privacy. Instead, they served to bolster the industry’s argument that chemical retardants save lives.

In the last quarter-century, worldwide demand for flame retardants has skyrocketed to 3.4 billion pounds in 2009 from 526 million pounds in 1983, according to market research from The Freedonia Group, which projects demand will reach 4.4 billion pounds by 2014.

As evidence of the health risks associated with these chemicals piled up, the industry mounted a misleading campaign to fuel demand.

There is no better example of these deceptive tactics than the Citizens for Fire Safety Institute, the industry front group that sponsored Heimbach and his vivid testimony about burned babies.

There’s lots more where that came from. Just don’t buy products, for backpacking or for home, which contain FRs. It’s YOUR health.

Cheers

[Sam Farrington]

Vendors do not often identify coatings as TPU, but many do identify coatings on nylon as sil on one side and PU on the other.  Whether these are TPU or not, I’ve found they have superior performance for very light weight nylons – 7-20D (for tents).

You mention pack fabric for your needs. Cordura brand fabrics go all the way down to at least 30D. The weave is obviously different on the heavier Cordura, a heavier and rougher weave.  Assume you are looking for a pack fabric that is highly water resistant, very strong, and extremely puncture and abrasion resistant as well.

Many have gone to non-woven materials, sometimes laminated to woven ones, that are discussed at length on BPL, and often referred to by vendors as X-Pac.  Personally, I do not like them because they are quite stiff, just the opposite of what I want in a pack that will mold to my body, be easy to stuff, and provide easy WP zipper access. They also have none of the self-repairing qualities of woven fabrics when sewn.  The solution to the latter is to bond the pieces of the pack together.  Again personally, cannot think of a bigger PITA.   But many have gone this route with X-Pac.

But if you are looking for the best woven materials for a pack, I think 1000D, either Cordura or ballistic nylon, is overkill.  Sure, you can drag them and bang them on rocks, but what is that going to do to the gear you have inside the pack? The nylon fabrics with spectra in a ripstop weave are bomber, and weigh less than a quarter of that.  But even those weaves are rough enough that it is difficult to coat them to a high degree of water resistance. Look at RBTR’s pack fabrics and try to find HH specs for water resistance like they provide for tent fabrics.  I could not find any. Ditto, for Rockywoods and Quest Outfitters.

However, at Extrem Textil, I did find firsts and seconds of TPU coated 500D Cordura nylon rated for water resistance at over three times the minimum 1500mm HH waterproof standard.  They state that the TPU coat makes the fabric stiffer than a PU coat, but do not indicate by how much:

https://www.extremtextil.de/en/cordura-500den-tpu-coated-hf-weldable-370g-sqm.html

https://www.extremtextil.de/en/cordura-500den-tpu-coated-hf-weldable-370g-sqm-2nd-choice.html

They also have some other TPU offerings on the next product page:

https://www.extremtextil.de/en/fabrics/coated-fabrics.html?p=3

Hope this is will be helpful in finding what you are looking for.

[Luke F]

I was told second hand that a mill said 500d cordura and similar just wouldn’t take a silicone coating, mostly due to texture if I recall.

TPU coatings do seem to hold up better, but personally I have been happy with xpac and just not dealing with coatings anymore. That said I have seen several older xpac packs (Mountainsmith dabbled in the early 2000s? and an old Wild Things Andinista) where the delamination is nearly complete and cutting the fabric open the PET film on the inside has mysteriously left, so nothing lasts forever.

Seattle Fabrics has some nice looking TPU coated pack cloths I’ve been tempted to make something out of, and since they are heat sealable you could probably do some fun things with welded construction.

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