(Yay.. I didn't burn down the house hehe)

still a fresh experiment, but first tests seem promising :) (see you-tube video above)

No water or ink required, just paper, sand and fire.
Could probably be done to leather, cloth, even wood, but wood would require a longer hotter burn to singe.
The writing is water proof, once made, there is no ink, so it wont run or smudge no matter how wet it gets. Also, because crossing lines "cuts" the previous line, there might be some cool ways to use that in a script.

Cover paper with sand, wipe lines in it with a stick, fingers or anything, and set a small fire on top.
The paper will singe, but the sand will prevent it from burning, and control singing to the line due to heat sinking and controlled oxygen flow. Also, from my basic chemistry understanding, I imagine the vapors from the burning material are leaving some residue that stains the paper.
Burning paper kinda sucks, had to do multiple burns cause it burns so fast, but the ash builds up, when I try to remove the ash in between burns it disturbs the sand and exposes some areas a bit:( 

I think it will work much better with small burning sticks laid just above the sand .Build up the edges a bit so they don't actually lie on the "drawing surface" but instead are just above it. (not too keen on the idea of starting a small camp-fire in my house lol, but using sticks for one long burn and not poking around should improve the quality)

The last image in the video shows the carbon marks left on the floor beneath the paper. They wipe off easily, but it would seem that if I try with several layers of paper I might be able to produce multiple copies at once. Primitive "carbon copies" hehe

Not sure what to call it, yet thinking something like "blazing sand script" or “FireScript” or even “SandScript” (though that might be easily confused for Sanskrit) hehe..
Also, If this was how a culture started their writing system I can imagine it evolving into tons of other methods eg, pouring molten material into sand molds, filling with powder that melts with heat then congeals, etc.. so the writing system could be integrated into many other arts and crafts as it evolves

The medium of lines in sand is fun. As Alex pointed out in the thread about Nailscript, crossing lines in clay like cuneiform might be able to distinguish depth layer to some extend as well. This sand is a similar case that demonstrates that concept I think. Although this takes it to the “extreme” because the sand actually cuts the previous like and leaves 2 “walls” on either side of the second stroke. Varying stroke width, specifically, using increasingly thin strokes should allow multiple crossings in one location.

Maybe when I find a beach where fires are permitted, or when I finally move back to North-America and have a back yard, I can develop it further.

Since I have now put it on the back burner, sharing it, maybe someone else has the means and ideas for a next step or some application. 

Hope you guys like :)