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.
I’m going to have to give this another try. A few years ago I bought some from Gossamer Gear and tried it as a ground cloth in my back yard. It ripped almost instantly so I gave up on it right then, assuming it was just too fragile. Maybe I just got a dud. Still have one in my tent gear box so I’ll dig it out and try again.
Very surprised. I’ve been using mine for 15+ years and never, ever, torn or punctured one.
Is it slippery when you stand on it while using it as a porch? I use 2 mil plastic as a foot print, but I know the 2 mil is a bit heavier than polycryo. I have about 50 nights on that piece. Do you know how the 2 mil plastic compares to polycryo with regards to durability?
You use it on ground not a smooth surface, so it’s nit slippery.
It’s a remarkable material. I’m continually amazed by how durable it is. Each morning I fold mine into a quart-size ziplock freezer bag (unnecessarily big, but easier to handle) and then just add it in with my shelter’s stuff sack. If the groundsheet is particularly wet from ground moisture, I sometimes keep it accessible so I can unfold it at lunch to dry out.
…or just go to Home Depot and buy some?
That’s why I included a link to Amazon. If you buy it with Prime you get free shipping.
I find that the SOL Survival Blanket 58″ X 98″ X 1mm thick (at 92g) is also almost indistructile Plus it’s silver, aluminized side is 90% heat reflective & thus can work as an emergency blanket. And the blaze orange side can be used for an emergency signal if required. So, multi-purpose.
That is probably 1 mil, not 1 mm. A “mil” is a thousandth of an inch, or 0.0254 mm. A 1 mm thick ground cloth would be very thick.
Trash compactor bags used to line a pack vary from 2 mil to 4 mil thickness, depending on the brand.
Thanks SPOCK for letting everyone know the difference between 1 mil and 1 mm. I’m sure we would all be lost without your amazing insight.
Down boy. Walter is a nice guy and doesn’t need your wit.
Polycryo, is strong and puncture resistant but it will tear along certain plains. We ripped one, once, while violently shaking the dirt and condensation off. Shake a little less vigorously now and haven’t had the problem again.
It also will shrink from wrinkles and heat, so you want to start 25% to 50‰ larger. It will still be crazy light.
I’ve got some polycryo that I’d like to give away for free. It’s Duck Brand Window Film. It was a 120 inch by 84 inch piece, that I cut into two pieces. One piece is 36 by 120 inches and was used once. There’s some forest debris here and there on that piece, but it’s otherwise in perfect condition. The other piece is 48 by 120 inches and is brand new (never used). The package says that the sheet weighs 4 oz. However, on my kitchen scale it came in at about 8.5 ounces. The only thing I can figure is that it’s 1.5 mil thick polycryo instead of .7 mil thick polycro as the package indicates. Are you interested in it? If you’re not interested, do you have any suggestions as to where I can give it away for free? Thanks!
Reddit /ultralight. I’m sure it will get snatched up quickly.
Phil!! Thank you so much for this little article. I’ve got a Big Agnes Fairview 3, which isn’t made anymore, so trying to find a footprint for it is ridiculously difficult. BUT the large Gossamer Gear footprint is almost the size that I need (96 x 72 and the Big Agnes was 84 x 72) — Wooohooo!
Great articles, Phil – thank you!
Questions re. Polycryo… Do you know if it can handle being staked down with those skinny micro stakes without tearing? Likewise, can it handle grommets if doubled/quadrupled first?
What’s your thoughts on 1.5 mil polycryo vs the.7? It seems the “extra weight” would be about an oz, and one would think twice the thickness is better. Is there a reason no one uses it?
Appreciate all the reviews and insights you provide.
I’ve haven’t bought any new polycryo in a long time, so I wasn’t even aware that you could get it multiple thicknesses. I rarely use it anymore and just pitch my tent on the ground…but then again I can do that without much abrasion in New Hampshire and Maine. I doubt it matters much, other than durability/weight which you get.
I experimented a little this summer with using polycryo as a tarp. Since they’re no grommets, you have to put a pebble at the tie points to wrap your line around, but I think it works pretty well with braided dynema fishing line. Has anyone else tried this?
There was a company called Gold Gear, circa 2013, that sold a polycryo tarp. here’s a link to an image.
if you search on “gold polycryo tarp” in google you’ll see a lot of examples of tents and tarps people have made with the stuff.
How do you stake it down? Or are you just putting your tent on top of it?
You just pile your tent on top.