Inaki;
I devoutly hope the current stock of 'heavier' silnylon is better than the stuff I used. Even more, I hope manufacturers do their own testing to ensure that each shipment is up to spec.

A good 1.8 or 1.9 oz. would be desirable at least for bottoms and other rub points on packs.

What I REALLY want is a lightweight fabric reinforced with Spectra or Dyneema (the rest of the world's name for Spectra): preferably a polyester for its UV resistence and low water uptake. The wish list includes a super UL fabric (dare we hope for 0.10 oz.?) for tarps and radical SUL packs as well as something in the 1 oz range for UL packs.

The design situation with Spectra and other ultrahigh molecular weight materials is similar to what we experienced with Nylon in the early days and still see in conventional backpacking gear: Our *perception* of a fabric's strength and suitability is based on our experience with weak fabrics. We just can't believe that a 1.1 oz. nylon fabric can be as strong as it is -- until we have some experience with it. It just don't seem right.

Our perception gap gets even worse with fabrics below 1 oz. And the prerception issue gets bigger with super materials such as Spectra - which is 3 times stronger than Kevlar - let alone nylon. So, what kind of fabric could you get if it were reinforced with fibers 15 times stronger than steel?

1.1 oz silnylon used in parachutes etc. is
type 66 nylon, same used in climbing ropes.
Stronger than the cheaper type 6 is used in most fabrics.

Yep, 66 is stronger than 6. And I'm glad. But nylon still can't hold a candle to Specra. It's just that Spectra hads a lower melting temperature, so it doesn't calender (heat set) at the same temperature as nylon or polyester... So getting a tight weave that doesn't pull out of shape is trickier.

Brain weight probably has more to do with backcountry safety than equipment weight.

I carry more first aid gear gear than most ultra-light gear lists show, but the philosophy of less-is-more certainly helped me cut down there as everywhere. It is the main area that really struck me as a safety issue with UL gear lists-- I really want more back-up than a few bandaids and some moleskin.

I agree that lighter loads are safer for balance, falls, stress on joints, overexertion, dehydration and heat-related issues.

Many in this thread have concerns with durability. New materials breed new techniques. This has come up in many areas: bicycle, motorcycle, automobile and aircraft design all come to mind. Again, the less-is-more concept makes for lighter gear, first of all be leaving off all the extraneous fittings, pockets, zippers, etc. Next the load in the gear is lighter for using the same less-is-more concept and the lighter materails used-- we get a nice snowball effect right away. THe lighter pack load allows use of lighter materials and the snowball continues to grow. Thin fabrics require a little more attention, but I was never a fan of throwing my gear around or sitting on my pack as one person told of here. I've seen some sleeping bags ripped now and then, but is was more inexperience and accident than material durability.

The other area of the safety of UL gear centers around appropriate gear for the conditions-- going beack to brain weight rather than gear weight. Knowing how to pitch a tarp takes a little knowledge and practice. Tarps make sense to me in summer, but offer less protection in windy wet weather in fall/winter/spring travel. I live in wet country and prefer a little more shelter than a tarp, but going back to the less-is-more idea, I don't need a 10 pound tent to keep myself dry either.

Another related question to ask: is UL travel healthier? I think so. It is less stressful on body parts, and offers better protection from heat-related issues. The effect on attitude and enjoyment of the journey goes without saying.