With time on our hands due to the Covid19 crisis, we're reviewing some of our techniques and equipment...making sure everything works and was put away right. Things like our Tyvek ground sheet.
We use this under our tent to reduce wear and tear on the tent, and even help protect our Neo-air mattresses--this after we found a couple of pin-hole pricks in those air mattresses after a night on a bed of pine needles.
Of course you want to fold up your ground sheet into as small a package as possible, but there is also that old physics/math problem: you can't fold any piece of paper (or other material) more than seven times.
Here's our solution for getting your ground sheet into a nice, tidy, and small package.
First make sure it is dry and clean. In the rain, all bets are off. Stuff and go.
The first fold is across the the longitudinal axis--making it half as long, but still as wide.
The second fold goes the other way, so that now you have two edges that have folds on them, and two that do not. That's important. Keeping those unfolded edges clear is how you make sure you fold all the air out of your ground sheet.
Fold one more time, again, back along the longitudinal axis.
You now have a ground sheet that is roughly 1/8 the size of the original. Good.
Now the truly tricky part. Fold the thing in thirds, folding first the side with the open edges and then the side with the folds on the edge. This gives you a long strip of ground sheet, almost like a tube, and the only open edges are at the end of the long strip.
Now the second secret. Begin to fold this long strip from the folded end towards the open edges end. Fold over about 1/5 or 1/4 off the ground sheet. Smooth out that fold, and do that again. This forms a nice, tidy block at the top of the strip, and still leaves the open edges at the bottom.
Now begin rolling from the folded section towards the open edged end. It will roll into a very tidy package.
Stuff it into your pack, and look for a way to wash your hands. It's too late, You've already packed everything up, the ground sheet was what you used to keep everything clean while you folded and stuffed everything else into your pack.
But everybody is waiting for you.
Time to hit the trail.