Q: Is it possible to make floating pigments, to get a smiliar Suminagashi effect using natural / sustainable materials?

 Recently I have met a friend who is using the Japanese technique of paper marbling called Suminagashi to make some really beautiful effects .

It seems that specific chemicals are being used to get the pigment colors.

If I understand correctly, for this process to work, the water needs to be more dense than the pigment that float atop of it. So I assume, the name of the game is to add something to the water to make it denser? (possibly)... ? or  possible as the natural way to accomplish this would be working with how water and oil  repels one another?

  Q: Is it possible to make floating pigments (watercolor or oil), to get a smiliar Suminagashi effect using natural / sustainable materials? 

Reason: I am designing a possible longer type class series. 

"Books, Paper, & Poetry" <-- click to explore idea.