Ground sheet sun shade

Any shade can be better than none so I can see the value. Housewrap has a high albedo I believe

I hiked the PCT few years ago, and if I were to do it again I’d make a small tarp from:

https://www.seattlefabrics.com/56-70-D-Metallic-Coated-Nylon-Ripstop-1995-linear-yard_p_40.html

The material is relatively light, and you’d only want a small piece to avoid having the wind blow it around too much.  I don’t know how well it’d work in practice since I’ve never actually used the material, but I’d at least give it a try.  I could always trash it or ship it home if it didn’t work as intended.  I will say that cuben fiber and 20D ripstop nylon tent flys don’t work great… they tend to just stop any breezes and trap in radiant heat like a green house.

I second Edward’s point – in the desert, ANY shade is valuable!  The goal is just to block the direct rays of pounding sunlight, so “brightness” is not an issue to me.  And as for size, whatever you already have on hand is fine.  I would not increase the size/weight of the ground mat I carry every second of every day just to increase the synthetic shade I might use on some days. Over-thinking the issue.

I usually use polycryo under my tent. The question is, if I were hiking the desert, would it be better to change to Tyvek, for a multi purpose use? I don’t deal well with heat, so holing up during hot weather in the middle of the day seems like a good strategy.  A shade shelter sounds good, if I’m already carrying it, one reason I wondered about my DCF rain skirt. Pretty small, though.

Tents in the middle of the day do trap heat, more than provide shade, so you’d have to  fly it in such a way that it was open on most sides. Would the reflective coating on the ripstop also work to reflect body heat back at you if used as a groundcloth?

If you want to try, Tyvek can be died. There are discussions on the site and I have seen a coworker successfully do so.

In theory it should help with insulation, though what magnitude of practical effect that translates to I do not know.  Just to be clear, I have never purchased that material, nor made a tarp from it, and so I am not specifically recommending it.  Mostly I am just saying that in my experience tent fabric and cuben fiber are not nearly as good as you might suppose — even with the sides open.  On the PCT I tried an emergency blanket, but it was just too fragile and finicky to be useful.  All I really know is that if I were to hike the PCT again, I’d personally give that fabric (or something like it) a go in tarp form to see how it goes.

I assume you are looking for something larger than an umbrella.

Tyvek gives great shade under it.  It is white but not translucent.  Yes, grommets make it easier to pitch it out.  Most retro-fit grommets I’ve seen are way overkill, accommodating 1/4 or 3/8″ rope.  For the 2mm and smaller guy lines we use, it could be just a rivet or a clothing snap with a small hole drilled in it.  Or just apply a 1-inch square of duct tape, Gorilla Tape or Tenacious Tape to each side and punch a hole using a hole punch for paper.  Or wrap the corner of the Tyvek around a pebble to create a tie-off point.  Or, since Tyvek is quite strong and almost tear-proof, just a hole punched or burned in the Tyvek itself.

Yes, any shade in the desert helps a lot.  On kayaking trips in the Sea of Cortez, we’d take a mid-day siesta under the spindly desert bushes that offered only about 20% shade.  But they DID offer some structure, enough to drape our clothes or tent on and thereby create some solid shade underneath.  And if it’s really windy?  Your tent/tarp already has grommets in its corners.  Factor in which way the sun is moving and lay on the eastern side of your shade patch as the sun moves west (or the reverse for Roger) for a longer, shaded nap.

If I have my Chrome Dome sunbrella along, I’ll set that on top of a tall brush for any rest breaks, however brief.  Then I can take my break, in full shade, with both hands free.

David is on it – the Chrome Dome umbrella is the thing to have on the New Mexico desert part of the CDT. Between PCT and CDT hikers, the Chrome may well be the most agreed upon piece of gear. More hikers are using it on the AT, too, as a way to win the rain game. In particular, using the shoulder strap attachment method keeps you hands free for other things like hiking poles and such.

I lived in the desert for a while, while working.

I know it’s not exactly UL and may seem a little old fashioned but an “Original” HD space blanket is probably the first thing I would put aside; to pack at the very top of the rucksack; if I ever decided to do any more dry country hot weather walking