Many/most small PSK will include a mylar "space" blanket or a plastic sheet. I was wondering, if I needed to rig a sun shade to protect me from the rays of the summer sun while I rested during the heat of the day, would one material be preferable to the other?

Seems like the mylar would be the winner since it is not only opaque but also reflective, but maybe in actual use, there's little practical difference. Was wondering if anyone had any practical experience with this. I'm thinking of a worst case scenario like being in a semi-arid or desert region with no natural shade, like trees or geological features, so I would need to dig little trench, hopefully to find cooler ground, then put the sheet over the hole.

Thoughts?

We did tests in college in the desert of central washington.
Temps were close to 120 F.

The winner overall -- black plastic

The thicker laminated space blankets with the reinforcing threads came in 2nd.

The emergency blankets let a lot of light through (heat),
even with water sitting on top of the emergency blankets they were
hot.

You did have to be about 3 feet from the materials for air circulation or you would cook.

Of course.

Very interesting results. What exactly do you mean by "black plastic"? Do you mean something like thick, contractor-type black trash bag material?

And the "laminated space blanket" is the Space brand blanket--metallic on one side, red or blue plastic on the other side?

I'm rather surprised and disappointed that the basic mylar sheet performed so poorly in providing shade. Well, glad to learn something new about something I have been taking for granted.

I carry a couple of 3 mil contractor black plastic bag for sun shade however, I have never actually used it under field conditions. I also carry 8, eight inch cable ties and duct tape to make groments, etc. This set up was suggested by several arid/semi arid "survival experts" books or forums.

The mylar is a low performer becuase it's just a thin layer of reflective material on the plastic- hold it up to your eye on a sunny day and you can see through it.

Too bad the space blanket performed poorly. Along with black and white trash bags, when I hike in the summer I usually always carry a small unbrella specifically for sun shade. Hmmm, I might have to do some shade testing on my hike tomorrow.

After some "reflection" I'm not too surprised that the space blankets didn't perform well in the heat. After all, they are marketed to be used mainly in the cold. They may have been designed to allow sunlight through as this could provide an extra advantage in some cold weather situations.

I wonder how the AMK Heatsheet would perform as a sunshade? With the orange backing it would be interesting to see how it compares to the trashbag.

We used the sheets of plastic you get at the hardware store.
They were the heavier gauge. The thinner you go, the more heat
gets through.

They also make good solar stills.

The heavier space blankets were the one that were colored on one
side, red or camo or blue as you mentioned.

Thanks, Clearwater. I'm curious, would you mind describing this experiment you guys did a bit more. Was its intent specifically survival-related? And how were the materials rigged? On sticks like a flat tarp, like a lean-to, or simply covering a hole in the ground?