Quite a ride through the valley of risk assessment, which from what I’ve read, is a very debatable science. And there are other considerations besides hail damage.
Recall Ryan J’s post not long after Cuben became in use for tents. His photo showed seams with threads that had become very loose. Most likely because neither the fragile mylar, nor the unwoven Dyneems fibers could hold the threads tightly in place. So now we hear that some use adhesive without sewn seams. But also that the adhesives fail below certain temperatures, and lately the effects of heat have been raised as a concern. Which is good because the climate is getting warmer with no end in sight.
A problem with DCF is that the mylar on each side of the laminate is very thin and fragile, much more so than common kitchen materials like saran wrap. The mylar can be easily torn. But with the addition of Dyneema threads in the laminate, tents are manufactured.
Experimenting with adhesives applied to strips of DCF for the purpose of testing adhesion, I found that when the best 3M adhesives were used, DCF strips could be torn apart and shredded without a great deal of effort. But with ~half ounce DCF the material tore apart in many places along what would be the warp (parallel to the sides of the roll) if it were woven. With ~3/4 oz DCF, there was less tearing, but the Dyneema threads separated along the warp because the weft threads were not secure. They were just laid in place, but not woven with the warp threads, nor sufficiently held in place by adhesive. So the fragile mylar simply split apart when the warp threads separated because the weft threads were not holding them in place. On a tent, this would appear as splits parallel to the warp. However, if the warp and weft threads had been woven together in the laminate, this would not have so easily occurred.
DCF also has no bias stretch, so that when pulled diagonally across the warp and weft, there is no elasticity as there would be with a woven fabric. This makes it very difficult to get a tight canopy that will better resist severe winds.
In short, the concerns were:
– fragility of the mylar
– adhesive seams that would fail in excessive heat or cold
– absence of a weave between the warp and weft threads
– lack of bias stretch in the material
There are other concerns like the bulkiness of the laminate and additional pack volume needed for carrying. However these concerns do not relate to failure of a shelter, although they are a PITA for someone who values a compact pack that will keep a pack’s center of gravity close to the body. This is important to me to avoid excessive stress and long term damage to the spine; however, from the bulk and size of their packs, many backpackers do not appear concerned on this score.
As several on this thread have recognized, the most important concern is a viable shelter that will protect the user from unpredictable weather events, only one of which is hailstorms. We have also been treated to unexpected weather that brings severe cold, rain and wind, the most recent such event this summer in the NH White Mountains having resulted in one death, and a number of hospitalizations for hypothermia. Hardly a day goes by here without a search and rescue. What would happen for these folks in a large and less accessible wilderness area in the Rockies is something I don’t like to think about. A lifetime of hiking has shown me that such events can be reduced in number by prudence, but are also unavoidable at some point, particularly on longer wilderness treks. At such times a tent that will withstand the elements is our ace in the hole.
While it is certainly a pain to carry a slightly heavier shelter that would not be needed under most circumstances, I won’t hesitate to do so. When Dyneema or the like is woven into a fabric, well waterproofed, with substantial weight savings, I would pay for it. But not till then.
