In article .com,
"Dick" wrote:

The application of marbled colours is done by floating acrylic paint or
marbling ink on a "marbling ground" which is obviously water and some
additive. Can anyone tell me what that additive is to make the paint
float on the surface.

According to a couple articles in American Woodturner a few years back,
carrageenan is most commonly used as the size. The articles are in the
Fall '02 and Fall '03 issues, written by Mary Thouin and Jacques Blumer,
respectively.

--
"Sure we'll have fascism in America, but it'll come disguised
as 100% Americanism." -- Huey P. Long