Polycro Thickness

[tschwan22]

I am going to get some window shrink film to make a lightweight ground cloth for my tarp and was wondering if anyone has tried the "heavy duty" versions (1.5mil) and can compare them to the normal weight ones (0.7-0.75mil). Are they considerably more durable? Worth it for the weight?

Thanks.

0.7mil:
https://www.amazon.com/gp/aw/d/B000NHW2Z6/ref=aw_wl_ov_dp_1_4?colid=G789N7OIB2UB&coliid=I23OIBUPUU41N8&vs=1&th=1&psc=1

1.5mil:
https://www.amazon.com/gp/aw/d/B015PY2BTS/ref=pd_aw_sim_60_of_10?ie=UTF8&psc=1&refRID=ZRT377N0S130A3EFHR5H

[Ethesis]

People who have used .7 mill report it as very durable.

I'm planning on trying it to experiment. But I only use my tarps to stay fry while setting up my tent.

But there have been some online posts of experiments.

[Ethesis]

https://backpackinglight.com/forums/topic/59450/

[tschwan22]

Sorry, I guess my first post was not clear enough. I will be using the polycro as a ground cloth, not as a tarp. I already have a silnylon tarp. The reason I specified tarp is so that you know that this will be my only floor; it's not there just to protect another floor.

Thanks.

[hyperslug]

I once heard that heavy duty polycro might be more less tear resistant as a ground cloth. I also heard great things about Gossamer Gear polycryo ground cloths. But have no ideal what the truth is and I will mostly use a tarp on my thru-hike with polycryo so would also like to hear thru hiker's experience.

[cmoulder]

Polycryo is a tough material but its longevity is subject to so many factors that one person might get incredible service from 0.7 mil and another would immediately destroy 1.5 mil. Get some and try it, and make sure to have some tape for repairs. Duct tape works fine, as will just about any other tape.

My problem with polycryo is that it is super slippery — especially on snow! — and even on grass and leaves it slides around a lot for me. Probably not so bad on sand, dirt or rocks? Seems I always come back to good ol' Tyvek housewrap... not the kite stuff.

[ggreaves]

Polycryo

ha ha. drives me nuts. no such thing as polycro. somebody in a hiking forum misspelled it way back and it took on a life of its own.

[colorado_rob]

ha ha. drives me nuts. no such thing as polycro. somebody in a hiking forum misspelled it way back and it took on a life of its own.Yikes!!!!! Not sure if I was anywhere near the first, but I've always spelled it wrong (without the Y), and I've been using it for a zillion years! Ain't that a hoot.

BTW, I've used the Gossamer Gear 0.75 version for my Zpacks tent floor for years, finding one sheet last me maybe 40 nights or so before I feel I need to replace it. The medium 0.75 versions come in two-packs for $10. For some reason I trust this better than the window film version. Could be just marketing, but I like GG stuff:

http://gossamergear.com/polycryo-tent-ground-sheets-protection.html

[Elaikases]

I once heard that heavy duty polycro might be more less tear resistant as a ground cloth. I also heard great things about Gossamer Gear polycryo ground cloths. But have no ideal what the truth is and I will mostly use a tarp on my thru-hike with polycryo so would also like to hear thru hiker's experience.

Gossamer Gear sells .7 and 1.0 ground cloths with no complaintes.

[tschwan22]

Dang, I just assumed that was how it was spelled. I think I'll get some of the thinner stuff and see how it works and if I need something more durable then I'll get the thicker.

Thanks.

[cmoulder]

Colorado_rob that's a good data point for me since I haven't used it that much... What surface do you use it on primarily?

Where exactly do you put it? Is it a ground sheet under a cuben floor?

thanks,

[nsherry61]

ha ha. drives me nuts. no such thing as polycro. . .
Is there such a thing as polycryo either? What is the origin of that term.

The plastic we are talking about and using is a crosslinked polyolefin. I'm not sure how one gets polycryo out of polyolefin.

I've only ever seen the term polycryo, or polycro for that matter, used in backpacking forums and backpacking web sites. Is either ever used anywhere else?

[Miner]

Since 2008, I've been buying mine from Gossamer Gear, size Medium which gives you two 0.75 mil thick sheets. I'm too lazy to buy it in bulk and cut it to size for myself. They normally last a long time. I normally throw one out after 1 to 1.5 years of use; usually after I forgot to dry it when I get home and it sat for weeks folded up. More because of the mildew smell then any real damage.

When I hiked the PCT in 2009, I used the same sheet from Mexico through Oregon. It had a few small holes in it (mostly from SoCal) that I had stuck some small pieces of Duct Tape to repair. Since I had a spare in my bounce box, I replaced it for Washington, otherwise I'd have been fine carrying it to Canada. I usually cowboy camp if at all possible and use a tarp when it actually rains. Worked well on the PCT for me.

[cmoulder]

Is there such a thing as polycryo either? What is the origin of that term.

The plastic we are talking about and using is a crosslinked polyolefin. I'm not sure how one gets polycryo out of polyolefin.

I've only ever seen the term polycryo, or polycro for that matter, used in backpacking forums and backpacking web sites. Is either ever used anywhere else?

That's a good question and observation... I too have never seen it mentioned as either -cro or -cryo elsewhere.

However a bit of googling turned up this material which might have been the polyolefin variety first used for the purpose, Cryovac Polyolefin (https://www.uline.com/BL_2408/Cryovac-Polyolefin-Shrink-Film), hence polycryo.

All I knew previously is that polycryo is the way Glen Van Peski spelled it and that's good enough for me. :)

[nsherry61]

. . .All I knew previously is that polycryo is the way Glen Van Peski spelled it and that's good enough for me. :)
So, maybe the origin of the term Polycryo is an invention of Glen for Gossamer marketing purposes?
He needed to call it something simple and different?

I find it interesting, since cryo mean cold or frozen, which I don't automatically associate with sheets of plastic.
Cryovac is a brand name originally associated with shrink wrapping frozen food if I skimmed the web pages adequately.

But, why use the brand name in this way in this context? Maybe we should ask Glen if he has memory of its origin?

[Puddlefish]

My test of the stuff failed badly, when I shook the water off it and it ripped in half. Maybe if I'd taken a whole lot of care when cutting it, to keep the cuts smooth and not introduce any edge tears. I'd also be concerned about slippery, as probably a third of my tent sites had some sort of tilt to them.

[scrabbler]

What stinks about polycro is that you cant tell easily which is dirty or clean side. Soon enough you have "both" side dirty, then I guess it doesnt matter. Huh.

[cmoulder]

What stinks about polycro is that you cant tell easily which is dirty or clean side. Soon enough you have "both" side dirty, then I guess it doesnt matter. Huh.

Write "TOP" on one side with a Sharpie marker. ;)

[Miner]

I can tell because I always fold it the same way. The topside is always on the inside of the first fold since the bottom is likely damp or at least dirty.

[colorado_rob]

Colorado_rob that's a good data point for me since I haven't used it that much... What surface do you use it on primarily?

Where exactly do you put it? Is it a ground sheet under a cuben floor?

thanks, I use PC in lieu of the expensive ($90?) and heavier Cuben floor sold by zpacks. The floor of the "raw" Hexamid Solo+ tent is bug netting, I put the custom fitted PC sheet on top of the netting to make my waterproof tent floor. I have little loops of cord taped to the six places on the PC sheet which clip into the tent corners and sides. IIRC the normal and expensive Cuben sheet is 4 oz, my PC setup is 2 ounces.

BTW, I recently tried using a piece of 1443 Tyvek, something like 4.5 ounces for the same setup, but I cut it larger to make more of a bathtub shape, tough call which I like better, I suppose the Tyvek a slight bit, but it is 2.5 ounces heavier. For a thru hike, I'd carry the PC.

[cmoulder]

Ok thanks! I'm thinking that the netting might make it less slippery. I used mine with the Duomid as my only floor, gathered at the corners which created something of a bathtub and clipped in similar to yours using some 2.5mm shock cord. For a while I also tried it as a ground cloth for my Duplex but found it redundant... the 1oz Cuben alone suffices, and it isn't slippery. I'm sticking with my Tyvek (housewrap) bathtub for the Duomid.

Those weight numbers are right in line with what I've seen. My Tyvek bathtub is a bit over 7 oz(!), but it is perfect in every other regard and thus remains in the kit.

[fastfoxengineering]

If your gentle with your gear the regular GG ground sheets last a while. Mine has about forty nights on it and is still in good shape. I just crumble it up and stuff in the outside pocket of my pack too. Its kinda slippery, whispy light which is annoying in the wind, and gets gross when the grounds a little muddy. But what ground sheet doesn't.

I don't think the weight of a silynyon, cuben, or tyvek sheet offers much more for the weight increase.

All three are easier to handle than polycryo though imo.

It would be my first choice on a long distance hike where hiking the distance is the goal and I just camp to sleep at night.

So yeah, don't abuse it and they hold up well.

I've heard of a few people using only to sheets on one of the big three trails.

A cuben floor would be real nice though, allbeit expensive

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