I do not wet the tissue until it has been rolled, as it will have a tendancy to stick to you fingers and go stringy when you roll it if you do.
I use good quality facial tissue, as it tends to get the nice wrinkled look where the roll is tied.
- Fold the edges toward the middle as all the loose edges look odd if left on the end of the roll.
-Fold the top and bottom toward the middle, but overlap them by about 5mm. This will stop the tissue from wearing through in the centre spot.
- Fold the sides again, but 1/3 on one side and 2/3 on the other to offset the join again.
- Fold the top and bottom, again fold the top onlt 1/3 of the way, and the bottom 2/3 of the way.
-Now fold in half , one edge to the other edge
-Fold the top down 1/3, and then roll the tissued from where you just created the bent edge but before you roll the last bit put a drop of cyano on the tissue to HELP hold the end in place - don't let it unroll.
Place a piece of ship makers rigging string, or whatever thread you use, at the end of the tarp and roll the tarp onto it so that it is in the centre of the thread. Then loop the thread around twice and tie it. Leave the ends reasonably long so that you can hold the roll by the loose ends and dip it in a mixture of PVA and white glue. I use an old Aerosol cap (the type off spray cans) to hold the glue mix. Then I loosely tie the roll threads into a loop, so I can slide a piece of sprue through it. That way I can put the sprue across the top of the cap, so the roll can dangle in the mix for a while. When completeley soaked just lift up the sprue and put it over an empty aerosol cap so the excess glue can drip off. If you want to, you can snip off the loose threads and press the almost dry roll onto the model for shaping and drying , and it will stick to the kit with the PVA. If you plan to leave it reasonably loose, just leave it to dry before painting. In that case leave the loose threads on the roll until after painting, as you can use these to hold the roll for painting and drying.
If you want a reasonably flat folded tarp, again shape it by folding, and then dribble PVA and water mix on it after it is shaped. It will soak up the PVA and when whet you can use an old paintbrush or needle to shape the wrinkles in the tarp.
Here's a couple of pics to show hat I mean:
