Gossamer Gear Polycryo is ultralight industrial-grade plastic sheeting that’s used as an ultralight ground cloth or tent footprint by many backpackers. It’s waterproof and surprisingly puncture-proof making it an ideal protective barrier for inflatable sleeping pads and ultralight tent floors. You can also cut and shape it with a pair of scissors to the size you need to save weight or make it easier to manage. It’s virtually indestructible and I typically use the same sheet over and over for a year or more.
Gossamer Gear was the first ultralight backpacking company to popularize polycryo (often misspelled as “polycro”) for ultralight backpacking and it’s still one of their most popular products. They buy the stuff in huge batches, cut it down, and sell it in two sizes: large (96″ x 72″) and medium (96″ x 40″). A medium sheet polycryo weighs 1.6 oz / 46 g and a large sheet weighs 3.65 oz / 104 g. A medium pack has 2 sheets and the large pack, one sheet. You can cut them down to any size after that.
For example, if I’m using a tarp for camping. I’ll spread a piece of polycryo down on top of the ground and lay my inflatable sleeping pad and quilt down on top of it to protect them from ground moisture, rocks, and pointy sticks.. I also carry a small square of polycryo to use as an ultralight porch under a hammock, to keep my feet clean when I get out at night. You have to weigh it down with some rocks to keep it from blowing away, but it works pretty well to keep leaf litter out of the hammock.
The sheets of polycryo you get from Gossamer Gear are really thin, so it helps to lick your fingers when unfolding a fresh piece because the layers stick together. When packing polycryo, folding it compresses it better than bunching it together, but it will never fold up as flat as when it still arrives. I usually stuff it down the front stretch pocket of my pack when I carry it, in case it’s damp with condensation.
Gossamer Gear’s Polycryo is constructed from industrial grade cross-linked polyolefin. It’s a waterproof plastic membrane that is used in everything from food packaging to building products. It’s also found in shrink-wrap window insulation kits, like Duck Brand Window Shrink Film, which you can also buy online and cut down to size.
Polycryo is also lighter weight than Tyvek Home Wrap as a low-cost and lightweight groundsheet or tent footprint. For example, the 5′ x 9′ Tyvek groundsheets sold by Zpacks weigh 9.25 oz or about 7 oz more for the same size protection. It’s even lighter weight than the super expensive Dyneema DCF groundsheets sold by Hyperlight Mountain Gear and a heck of a lot more abrasion-resistant.
I’ve been using Gossamer Gear Polycryo as a groundsheet for going on 15 years and it’s great stuff. If you’re using the footprint that came with your tent or Tyvek, Polycryo is an easy way to shave a lot of weight off your gear list at minimal cost.. Highly Recommended!SectionHiker is reader-supported. We only make money if you purchase a product through our affiliate links. Help us continue to test and write unsponsored and independent gear reviews, beginner FAQs, and free hiking guides.