Sand and Silnylon

While I prefer Sil, one of the reasons I switched to Cuben was how tenaciously fine sand clings to the Sil in the Southwest, especially on new or newer shelters. I was finished with my week long Sierra backpack before the last Moab dust was gone!

Nunatak, it’s helpful to hear that from you. Especially since I know from your instagram that you’re wandering around in the exact same zones as me. Just got back from Cedar Mesa and hosed off the Hilleberg and it appears as if the water is soaking in immediately where the door flap often falls onto the sand when the door is open. When I’m solo I often use a cuben duomid cause the sand doesn’t stick but where that fails is the zipper. The combination of sand and high stress from the inflexible cuben wears out the slider prematurely and it has to be replaced often. So it seems like zipperless cuben is probably the solution? Give me your thoughts on that if you could.

Zpacks Duplex, Triplex and Altaplex only have zips on the inner netting, not the outer doors but you can get them standard as outer only – without the inner and floor. The outer doors are overlapped with a mid point toggle closure. Zpacks Hexamids are also available without an inner.

If you want an inner and floor it would  be possible to add it using an inverted T opening in the inner walls with a bit of overlapping and perhaps magnetic closures.

Sometimes it seems that a static electricity charge is holding sand dust and other micro soil particles to my silnylon alphamid and gatewood.   I brush the dust and grit away but they often have a resistance to being brushed off.  Annoying as hell at times when less grit in the pack is on my mind.

I don’t have a cuben shelter but I don’t see the same attraction with dirt in my cuben packs nor a spinnaker tarp

The coatings on nylon tent and tarp fabric are quite different from the silnylon of the past.  They do not have the clearcoat look, and use PU in some combination with silicone.  One example would be Rockywoods very low denier 7D nylon.  I wonder if these newer, lighter and more water resistant nylon fabrics attract fine sand as much as the prior silnylon fabrics.

Kevin, Sam – I guess the sand being on the fabric bothers me a little bit too, but the bigger question is: to what degree it is wearing off the coating?

Mark – I’ll certainly consider those shelters in the future. duplex tent for two. either hexamid tarp or cuben grace tarp duo for one.

Based on my experience throughout the Grand Canyon and Southern Utah:

Silnylon tents (Big Sky, MLD): sand clings to silnylon

RBTR 1.1oz SilPoly PU4000 (tent floor, stuff sacks): sand clings to non-PU side of fabric, but less than above fabrics

20D silnylon (EE Recon bivy floor): sand clings to floor, still there after running under water

Rockywood 7D Silnylon (stuff sacks): will get dirty when dropped in the sand, but easily brushed or washed off

John H,  Thank you for your above post about your experience with sand.  It sounds like the coatings, not the fabric thread (nylon or polyester) are the root cause, and that the cling diminishes as the coating runs from conventional silnylon, to silicone with a flat finish and some PU, to primarily PU, at least the newer PU coatings we are seeing on products like the StoS Escapist tarp.  With that in mind, it seems that the floor suited to sandy areas should not use Sil for the bottom against the ground, particularly the older sil coatings.

I would be inclined to try Rockywoods 7D for a fly, probably with the PU side facing out, and for the floor would have sil only on the inside, not against the ground; and preferably with PU content in the sil inner coating also.  Most of the newer sil/PU coatings with a flat finish are primarily sil on one side, and primarily sil on the other.  This is easily verified by seeing how PU and sil adhesives adhere to both sides.  But seem to recall there are some coatings that use a mix of sil and PU for both sides of the fabric.  Will have to look harder to see what is available.

I have used floors with conventional ‘clearcoat’ silnylon as well as newer silcoats with a flat finish, and never had a problem.  But have never had to camp in areas with loose sand.   So will now design to minimize clinging sand, which sounds like a real PITA.  Thanks.

Sam, I’m glad you extrapolated what you did from John H’s post. I was sortof coming to the same conclusions. It seems like a full season of using a silnylon tarp in the desert, with stuffing and unstuffing everyday may result in a hardly water-resistant tarp within maybe only 50 nights of use. Assuming sand isn’t sticking to a PU coated fabric or a DCF fabric, stuffing those tarps repeatedly in the same sandy areas will not cause the same type of wear. Ron Bell has always said a Sil tarp will last maybe 500 nights and a DCF tarp will last maybe 250 nights in the same circumstances. Let’s just assume this is accurate for the sake of discussion. But if we add sand to the equation, do we think that both tarps are now in the 250 night realm?

I should clarify my post by adding that I sew RBTR 1.1oz SilPoly PU4000 and Rockywoods 7D silnylon with the PU side facing inside.

So for stuff sacks (mainly 7D silnylon), the PU side is on the inside. And for tent floors (SilPoly PU4000), the PU side is on the inside.

I’m not sure what effect the PU side facing out would have or how much sand clings to the PU side. It does seem like the PU side of my RBTR 1.1oz SilPoly PU4000 floor is always very easy to clean out. I like to keep the PU side facing inside to help protect it, since it’s supposedly what contributes to the higher water proofing. I always imagined it being less abrasion resistant than the sil-coated side (important for a tent floor).

That said, I never noticed any degradation in performance due to sand with any of these fabrics. They’ve all worked as intended, and eventually, the sand goes away.

John H:  Whoops!  Sounds like you are doing the opposite of what I concluded from your earlier post.  So much for extrapolation.  The big hassle I’ve had with other ground cover, like plain old dirt, is when it clings to the bottom of a floor, especially after rain heavy enough for water to flow under the tent and moisten the floor bottom..  And to some extent when it clings to the outside of the fly.  It is really a pain to try to shake out and pack up a wet tent with dirt clinging to the floor bottom or fly.  This happens less to inside surfaces, because they are drier (even with some condensation on the inside of the fly), and I’ve not had any problems with dirt clinging to the inside or top of the floor, even with smaller dogs in the tent, possibly due to care taken to keep moisture and dirt outside, and possibly because I’ve not camped on dry sand.  None of my usual haunts in Northern New England or Colorado, have ever forced me to do this.

So back to where I started, with the sil side facing out for the floor because it is more abrasion and crack resistant (if the flat finish sil behaves like the clearcoat), and because the PU side provides more friction for the floor surface inside. For the fly, not to mention vestibules, am not sure. Much depends on which coating is more resistant to heavy rain.   In bygone days, some conventional silnylons tested very high for water resistance, and some not.  Recall sending some first quality Quest silnylon to Roger for testing and it had an HH over 3000mm.  With the new hybrid coatings, I don’t think anyone has been testing to see whether water soaks the nylon fibers more on the sil or on the PU side.  But given what I know, the preference would be to have the PU (or TPU I believe Roger calls it) facing outward, in the hopes that it will be easier to shake and swab moisture and gunk off of it when packing up.

So will continue to avoid sand traps, and fold and roll up tents, with the outside floor portion facing out, brushing off the dirt as I go.  It takes some work if the floor bottom is wet, but after a sunny day and clear night of camping, most of the dirt is gone.  Looking for a nice grassy spot to pitch on also helps.  Don’t see any magic solutions here.  We are on the Gear not the MYOG forum here, so for many the decision about what coating faces in or out may be made by the manufacturer.

Sorry Ben K for the belated response to your zipper concern. And yes, I see that as a concern too. I try to use the zipper as little as possible and for that reason we chose a Cuben design where most of the functionality remains with only the no-see-um zipper closed and the main zipper left open. Even with a total failure we wanted the tent to offer near 100% protection. The choice to get this quality was a long, deep front entry shelter with a sizable vestibule (Yama).

Most mids and some side entry designs fall outside this category, with a heavy reliance on the big main zipper.

Of course in really inclement weather I have no choice but to close up, but as we know those circumstances are rare on the plateau.

Nunatak, if we’re talking about cirriform, (tarp and not shelter) can you get that pretty close to the ground if need be, with enough room that your Quilt isn’t touching the walls? Just to block some percentage of blowing sand? Also, Yama inners look pretty great for blowing sand with their tall sidewalls.

It’s the single wall 2p shelter w bathtub floor. At 6’2″ there’s plenty of room to avoid touching any walls in ground hugger mode.

I do not know of many UL setups that can keep blowing southwest dust out, floor or no floor. This one is better than most but still.

Wondering about zippers. First off I don’t know anything about camping in sand and its effects on zippers. It seems to me that a Vislon zipper would be less prone to issues due to grit/sand than a coil zipper. Like one could almost simply scrub and dislodge the sand with a toothbrush since it’s on the surface of the plastic teeth vs. getting caught in the zipper coils. Of course, the slider would require some sort of implement to clean it (a wire prick?). And I presume that sand eventually will still wear the Vislon zipper off.

Again, I don’t know Wondering about it. Hopefully others have real experience…

You are quite right: a toothed zip is more resistant to dirt than a coil-coil zip. But toothed zips usually only go down to #5 in size, while #3 is common for coil-coil zips.

Fwiiw, I use #3 coil-coil zips on MYOG tents and sleeping bags, and they have lasted for years. But we are careful with our gear, and I know novices can and have trashed #3 zips in the field.

Cheers

Nunatak, yeah we’re going to get covered in sand no matter what.

iago, i’ve wondered about vislon myself. definitely less sand will will get lodged in it, but the inflexibility of the teeth may prove detrimental? Not sure. Coil works in sand, more or less, because of its flexibility. It basically bends around the grains of sand when you slide the slider and the slider itself takes the abrasion and eventually wears out. Replacing it is no big deal. A bigger deal is when you have constant 20mph winds in a sandy area all night long and so when you open the door to go pee it won’t close again because there is too much sand in there to allow the teeth to close. Silnylon allows a degree of flexibility here, and the teeth will close more easily than with a DCF fabric which is too static. But then we’re back to my original question of whether or not silnylon is ideal because sand could be abrading the coating? Anyway. I like zippers for alpine use but maybe an open tarp is more hassle-free for these areas i’m talking about.

Roger, yeah I dig the #3 in alpine zones. Especially on flexible fabrics like silnylon and noseeum mesh. Always easy to swap out the sliders too.